Astronomy Test #2 Guide
Runaway greenhouse effect
- Accounts for why Venus has so little water and is so hot. - Higher temp increases evaporation and warmer air holds more water vapor. - Additional Water vapor further strengthens the greenhouse effect.
How did we get our moon?
- Our moon is way too big to have been captured so that can be ruled out - It did not form simultaneously with Earth because then it would have had the same features as Earth which it does not have, and it would be of similar density, but actually the moon has lower density than Earth -The leading theory is that we got our moon from a giant impact between our Earth and a giant mars-sized planetesimal which impacted Earth at such angle and speed that it knocked out Earth's outer layer to space which and that this material could have collected into orbit around Earth and then by accretion our Moon was formed. What supports this theory is that the Moon has a similar composition to that of Earth's outer layer and that it has a smaller amount than Earth of easily vaporized ingredients such as water which sounds right due to the fact that Heat from the impact would have vaporized it.
Key Facts of Mars
- Polar Caps -Southern hemisphere is more heavily cratered so it shows it is older than the northern hemisphere
Weather and Climate
- Weather is the ever-varying combination of wind, clouds, temp and pressure. - Rain Snow and Hail (Precipitation) - Climate is the long term average of weather.
Patterns
-Orbits are all on the same direction -Planets on the same plane -Heliocentric -asteroid Belt -Planets rotate on their axis, the same direction they orbit, except venus which rotates backward -Comets -Collisions -Elliptical The Sun once rotated much faster but has transferred angular momentum over time to other planets and interplanetary gas -Uranis rotates and its side -Venus rotates backward -Earth has a relatively large moon.
Atmospheres Chapter
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What are the necessities of life?
1. A source of nutrients (atoms and molecules) from which to build living cells 2.Energy to fuel the activities of life, whether from sunlight, from chemical reactions, or from the heat of Earth itself 3.Liquid water
Astrobiology
1. Learn about the origin and evolution of life 2. Discover new life 3. Find new habitable places
Terrestrial Planets
1. Mercury 2.Venus 3.Earth 4.Mars - Closer to the sun -Composed of Rocks and Metals -Rocky and Solid -warmer planets -Smaller Planets
Effects of Atmosphere
1. They create Pressure (determines whether water can exist on the surface) 2. Absorbs and Scatters light 3. Creates wind and climate 4. Interacts with the solar wind to create a magnetosphere (magnetic field) 5. Can cause greenhouse warming: visible light passes through the atmosphere and warks a planet's surface.
Acceleration of Gravity on Earth
9.8 m/s^2
Orbital Energy
A planet orbiting the Sun has both kinetic energy (because it is moving around the Sun) and gravitational potential energy (because it would fall toward the Sun if it stopped orbiting). The amount of kinetic energy depends on orbital speed, and the amount of gravitational potential energy depends on orbital distance. Because the planet's distance and speed both vary as it orbits the Sun, its gravitational potential energy and kinetic energy also vary However, the planet's total orbital energy—the sum of its kinetic and gravitational potential energies—stays the same. This fact is a consequence of the law of conservation of energy. As long as no other object causes the planet to gain or lose orbital energy, its orbital energy cannot change and its orbit must remain the same.
Reflecting Telescope:
A reflecting telescope uses a curved primary mirror to gather light which then reflects this light to a secondary mirror which reflects the light to a focus. - This telescopes are much shorter and fatter, and have longer diameters. - Most common telescope because they do not require high quality precisely shaped glass and because large glass lenses on the refracting telescopes are extremely heavy and can be held in place only by their edges, and the primary mirror of a reflecting telescope is mounted at the bottom, where its weight presents a far less serious problem.
Planetary size
A small planet cools down faster. A large planet can remain hot for longer. Potato analogy Size is therefore the primary factor in determining geological activity. If a planet cools down it is considered geologically dead. -The total amount of heat contained in a planet depends on its volume. -Loss of heat depends on surface area -Time for an object or planet to cool down depends on the surface area divided by volume.
Mass
Amount of matter in your body or an object
gravitational encounter
An encounter in which two (or more) objects pass near enough so that each can feel the effects of the other's gravity and they can therefore exchange energy.
What asteroid family could potentially collide with Earth?
Apollo Group
Asteroid Belt
Between Mars and Jupiter
Angular Momentum
Circular or turning momentum, as an object turns through an angle. The momentum that is attributable to rotation or revolution. The angular momentum of an object moving in a circle of radius r is the product mass × velocity × radius
Pluto
Composition: Ices and Rocks -5 moons - "ninth planet" -Part of the Kuiper Belt with Eris: Kuiper belt is much like the asteroid belt, except it is farther from the Sun and composed of comet-like objects rather than rocky asteroids. - Pluto's moon Charon is locked in with Synchronous Rotation, so Pluto always sees one face.
Tectonics
Convection of the mantle creates stresses in the crust called tectonic forces. Earth's continents slide around on separate plates of crust
Seasonal color changes on Mars are due to...
Dust Storms
Electrons in Atoms
Electron in atoms occupy levels whose energies are fixed, which means that they are charged by restricted energy levels.
Newton's Third Law of Motion
For every action there is an equal and opposite reaction This law is very important in astronomy, because it tells us that objects always attract each other through gravity.
Differentiation
Gravity pulls the more dense materials down and the less dense materials go up
If today is New Moon when would you expect to see Full Moon?
In two weeks
Gamma Rays
Light wave with the shortest wavelength and biggest frequency
Electromagnetic Wave
Light waves are traveling vibrations of both electric and magnetic fields. - Just as the waves on a pond will cause a leaf to bob up and down, the vibrations of the electric field in an electromagnetic wave will cause any charged particle, such as an electron, to bob up and down. - The distance between peaks in this row of electrons would tell us the wavelength of the light wave, while the number of times each electron bobbed up and down would tell us the frequency
Where in the Solar System would you find Olympus Mon?
Mars
Jim lives in a place where once a year, on the day of Winter solstice the Sun doesn't rise from below the horizon. Where does Jim live?
On the Antarctic circle
Where is Earth's inner core generated?
Outer Inner Core
Dwarf Planets
Pluto, Eris, charon.... -Small enough to be considered planets but large enough to be round. -Ceres: Largest asteroid in the asteroid belt
geological activity
Processes that change a planet's surface long after formation, such as volcanism, tectonics, and erosion. Earth is the most geologically active of the terrestrial planets due to its volcanic activity, earthquakes, erosion and other geologic processes.
Solution to the problems faced in the gound
Put telescopes in Space. That is why the hubble telescope has been successful despite its small size. - Our atmosphere prevents most light forms from reaching the ground.
What light waves pass through earth's atmosphere?
Radio and visible light, and the longest wavelengths of ultraviolet rays, and some of infrared. - The atmosphere does not scatter radio waves so radio telescopes can operate day and night.
Radio Waves
Radio waves carry so little energy that they have no noticeable effect on our bodies but they are strong enough to make electron move up and down by charging them making it useful for radio communication.
Key facts of Mercury
Resembles the moon but it is more heavily cratered so it tells us it is more ancient. - It shrunk in size when it cooled off. - Heavy impacts called basing - Large cliffs
Compared with the near side of the Moon, the far side is...
Rougher
SETI
Search for Extraterrestrial Intelligence
Solar Wind (a combination of high energy radiation (ultraviolet and x-rays, and a stream if charged protons and electrons)
So what happened to the remaining gas in the Solar Nebula that never formed part of a planet? They got cleared away by radiation coming from the Sun, which we call solar wind. Outflowing matter from the young sun blew away the remaining gas.
How is called a process of transition of matter from solid to gas?
Sublimation
Speed
Tells us how far an object will go in a certain amount of time. For example a car travelling at 100km/h will travel 100 km in an hour
What part of atmosphere does shield Earth from UV radiation?
The Ozone Layer
Net Force
The combination of all forces acting on an object. The net force is equal to the rate of change in the object's momentum, or equivalently to the object's mass × acceleration.
life on Mars
The combination of water ice and volcanic heat suggests that there could be liquid water underground.
electromagnetic spectrum (electromagnetic radiation)
The complete spectrum of light, including - radio waves - infrared light - visible light - ultraviolet light - x-rays - gamma rays
free-fall
The condition in which an object is falling without resistance; objects are weightless when in free-fall. Astronauts are weightless the entire time they orbit Earth because they are in a constant state of free-fall.
Intensity of Light
The intensity of a light is a measure of the amount of energy coming from a specific wavelength in the spectrum of an object. - At wavelengths where a lot of light is coming from the object, the intensity is high, while at wavelengths where there is little light, the intensity is low.
DNA
The molecule DNA can copy itself and pass by generic information from one gen to another. there can be errors or mutations and this explains how new traits are introduced. We all evolved from a common ancestor
Law of conservation of angular momentum
The principle that, in the absence of net torque (twisting force), the total angular momentum of a system remains constant. Because there are no objects around to give or take angular momentum from Earth as it orbits the Sun, Earth's orbital angular momentum must always stay the same.
Accretion
The process by which small objects gather together to make larger objects. This is how planetesimals formed
Radioactive Decay
The process in which a nucleus breaks apart or changes. Decay changes on element or isotope into another
What is accretion?
The process of clumping solid particles together.
Spectroscopy:
The process of obtaining spectra from astronomical objects. - The Spectroscopy of a star can reveal its temperature, composition, and line-of-sight motion.
For which planets is it possible for the Sun to remain overhead for years at a time at either pole and for the equator to receive almost no sunlight for years?
Uranus
Goldilocks Problem
Venus is too hot to have life and water. Mars is too cold and Earth is just right. Venus: - It would be much colder without the greenhouse effect - It has 200,000 times as much carbon dioxide as Earth so greenhouse warming is much greater in Venus - It has sulfuric acid rain, it does not have water, and the atmosphere is dry Earth: - Earth would be much colder (below freezing on average) without greenhouse warming - Our temp remained cool enough for liquid oceans to form - Most of Earth's carbon and oxygen is in rocks, leaving a mostly nitrogen atmosphere - Plants release some oxygen from co2 into atmosphere
Which asteroid from the list below does show sign of volcanism?
Vesta
What is the name of the first Mars Rover?
Viking
Key Facts of the Moon
Volcanic Activity seen in the Maria, craters are smooth and dark due to heavy impacts
Doppler Effect
We can learn about the motion of distant objects (relative to us) from changes in their spectra caused by the Doppler Effect. Train Example: As the train is closer to you the sound waves are bunched up between you and the train causing shorter wavelengths and higher frequency (high pitch) and when the train gets further away from you the wavelengths increase and the frequency decrease causing a lower pitch.
What happens when a comet approaches the Sun
When a comet is far from the sun it still has a solid icy nucleus. When it gets closer to the Sun its surface temperature increases vaporizing the ice into gas which is slowly released. Some of the gas drags away dust particles away from the nucleus creating a coma. As the comet gets closer and closer to the inner solar system the coma increases creating the comet's tail. The comet's tail points away from the sun
What day of the year is the Sun's position in the sky at noon the lowest for the NORTHERN Hemisphere?
Winter Solstice
How does the greenhouse effect warm a planet?
Without the greenhouse effect, Earth's surface would be too cold for liquid water to flow and for life to flourish. The greenhouse effect works by temporarily "trapping" some of this infrared light, slowing its return to space. So the energy that warms a planet comes from sunlight, also called visible light, and some of that visible light is absorbed by the surface and the rest is reflected back to space. Ultimately the absorbed visible light must return back to space and it does so in the form of infrared light and this infrared light is slowly trapped before returning back to space creating the greenhouse effect. This greenhouse effect only occurs when an atmosphere contains gases that can absorb infrared light Greenhouse Gases: Gases that are good at absorbing infrared light. - Water Vapor - Methane - Carbon Dioxide A greenhouse molecule that retains an infrared photon does not retain it for so long, instead it re-emits it as another infrared photon in any direction and then another greenhouse molecule retains again, and this happens again and again until it escapes to space. The total amount of energy a planet receives from sunlight will balance out with the amount of energy it returns: - A planet would heat up if it received more than what it returns - A planet will cool down if it returned more energy than what it receives. Without the Greenhouse effect a planet's avg temp would depend on: - Its avg distance from the sun - Its reflectivity This greenhouse warming is even more remarkable when you realize that it is caused by gases, such as water vapor and carbon dioxide, that are only trace constituents of Earth's atmosphere. Most of the atmosphere consists of nitrogen (N2)(N2) and oxygen (O2)(O2) molecules, which have no effect on infrared light and do not contribute to the greenhouse effect. (Molecules with only two atoms, especially those with two of the same kind of atom, such as N2N2 and O2,O2, are poor infrared absorbers because they have very few ways to vibrate and rotate.)
Jovian Planets
- Adding mass to Jupiter will actually make it smaller because it compresses the underlying gas layers -Jupiter and Saturn are both much larger and much richer in hydrogen and helium than Uranus and Neptune. This combination of modeling and experiment indicates that Jupiter has fairly distinct interior layers. The layers do not differ much in composition—all except the core are mostly hydrogen and helium. Instead they differ in the phase (such as liquid or gas) of their hydrogen. Uranus and Neptune are denser than Saturn because they have less H/HE. +Interiors of Jovian planets: - No solid surface but not fluffy either - Lots of layers - Cores made of hydrogen compounds, metals and rocks
The Moon's Tidal Force
- Because the strength of gravity declines with distance, the gravitational attraction of each part of Earth to the Moon becomes weaker as we go from the side of Earth facing the Moon to the side facing away from the Moon. - This difference in attraction creates a "stretching force," or tidal force, that stretches the entire Earth to create two tidal bulges, one facing the Moon and one opposite the Moon - Tides affect both land and ocean, but we generally notice only the ocean tides because water flows much more readily than land.
Mercury
- Composition Rocks and Metals - Terrestrial Planet -Smallest of the eight planets -Cratered, no wind, rain or volcanoes - You can see stars in daylight. - A world of both hot and cold extreme, because the tidal forces from the Sun have forced Mercury to have an unusual rotation pattern - Its surface shows hints of past geological activity such as plains created by old lava flows, and tall cliffs that hint planetary shrinking. - Mercury has high density, and it has a large and steady iron core
Circulation Cells
- Heated air rises at the equator - Cool air descends at poles - Without rotation, these motion would produce two - large circulation cells.
The Atmospheric History of Venus
- Its larger size allowed it to retain more interior heat, leading to greater volcanism. The associated outgassing released the vast quantities of carbon dioxide that create Venus's strong greenhouse effect. Venus's atmosphere consists almost entirely of carbon dioxide. It has virtually no molecular oxygen, so you could not breathe the air even if you cooled it to a comfortable temperature. The thick atmosphere makes the circulation so efficient at transporting heat from the equator to the poles that the surface temperature is virtually the same everywhere Venus has no seasons because it has virtually no axis tilt,* so temperatures are the same year-round. Overall, the total amount of water on Venus is about 100,000 times smaller than the total amount on Earth, a fact that explains why Venus retains so much carbon dioxide in its atmosphere: Without oceans, carbon dioxide cannot dissolve or become locked away in carbonate rocks.
What do you need for a habitable planet?
- Liquid water - Atmosphere - Magnetic Field - Energy - Time
Mars Geology
- Percival Lowell misinterpreted surface features seen in telescopic images of mars as canals and created canals -The system of valleys Valles Marineris is thought to originate from tectonics -Fluvial features -Dried river-beds -Details of some craters suggest they were once filled with water -Mars rovers have found rocks that appear to have formed in water -Low lying areas contain more water ice in mars (map of hydrogen content)
What factors can cause long-term climate change?
- Solar brightening: The Sun has grown gradually brighter with time, increasing the amount of solar energy reaching the planets. -Changes in axis tilt: The tilt of a planet's axis may change over long periods of time. -Changes in reflectivity: An increase in a planet's reflectivity—for example, from increased cloud cover, increased ice cover, or particles released from volcanoes—means a decrease in the amount of sunlight it absorbs, and vice versa. -Changes in greenhouse gas abundance: More greenhouse gases tend to make a planet warmer, and less make it cooler.
Facts
- Sunsets are red because red light scatters less with nitrogen. - Earth is the only planet with a stratosphere because we have ozone. - Aurora: Charged particles from solar wind energize the upper atmosphere near the magnetic poles, causing and aurora.
The Moon's Synchronous Rotation
- Synchronous rotation may seem like an extraordinary coincidence, but it is a natural consequence of tidal friction. - The Moon's synchronous rotation was therefore a natural outcome of Earth's tidal effects on the Moon.
Recording Images
- The camera lens bends light, bringing it to a focus on a detector (CCD) that makes a permanent record of the image. - Cameras also have a shutter which is like and eyelid, and light can reach the detector when the shutter is open. - Exposure time: Amount of time during which light collects on a detector. - Longer exposure time means that more light enters the detector and it allows the detector to record details that may seem faint in shorter exposures.
Why do atmospheric properties vary with altitude?
- The way in which temperature varies with altitude determines what is often called the atmospheric structure 1. Troposphere is the lowest layer, in which temperature drops with altitude (something you've probably noticed if you've ever climbed a mountain). The drop in temperature with altitude, combined with the relatively high density of air in the troposphere, explains why the troposphere is the only layer of the atmosphere with storms.The primary cause of storms is the churning of air by convection, in which warm air rises and cool air falls. Above the troposphere the air density is too low for greenhouse gases to have much effect on infrared light so they can travel much easily towards space without being absorbed. 2. Stratosphere begins where the temperature stops dropping and instead begins to rise with altitude. High in the stratosphere, the temperature falls again. The primary source of heating in the stratosphere is the absorption of solar ultraviolet light by ozone. Most of this ultraviolet absorption and heating occurs at moderately high altitudes in the stratosphere, which is why temperature tends to increase with altitude as we go upward from the base of the stratosphere.This temperature structure prevents convection in the lower stratosphere, because heat cannot rise if the air above is hotter. The lack of convection makes the air relatively stagnant and stratified (layered), with layers of warm air overlying cooler air; this stratification explains the name stratosphere. The lack of convection also means that the stratosphere has essentially no weather and no rain.Note that a planet can have a stratosphere only if its atmosphere contains molecules that are particularly good at absorbing ultraviolet photons. Ozone plays this role on Earth, but the lack of oxygen in the atmospheres of the other terrestrial worlds means that they also lack ozone. As a result, Earth is the only terrestrial world with a stratosphere, at least in our solar system. (The jovian planets have stratospheres due to other ultraviolet-absorbing molecules 3. Thermosphere begins where the temperature again starts to rise at high altitude.Because nearly all gases are good x-ray absorbers, x-rays from the Sun are absorbed by the first gases they encounter as they enter the atmosphere. The density of gas in the exosphere is too low for it to absorb significant amounts of these x-rays, so most x-rays are absorbed in the thermosphere. The absorbed energy makes temperatures quite high in the thermosphere (thermos is Greek for "hot"), but you wouldn't feel much heat because the density and pressure are so low 4. Exosphere is the uppermost region, in which the atmosphere gradually fades away into space.The exosphere is the extremely low-density gas that forms the gradual and fuzzy boundary between the atmosphere and space (exo means "outermost" or "outside"). The gas density in the exosphere is so low that collisions between atoms or molecules are very rare, although the high temperature means that gas particles move quite rapidly. Lightweight atoms and molecules sometimes reach escape velocity and fly off into space.
Newton's version of Kepler's third law
- This equation allows us to calculate the mass of a distant object if we measure the orbital period and distance of another object orbiting around it. - It shows that the orbital period of a small object orbiting a much more massive object depends only on its orbital distance, not on its mass.
Examples of Weight
- When an elevator moves up, you weigh more due to the additional force. - When the elevator moves downward, you weigh less
The Tidal Effect of the Sun
- When the tidal forces of the Sun and the Moon work together, as is the case at both new moon and full moon, we get the especially pronounced spring tides - When the tidal forces of the Sun and the Moon counteract each other, as is the case at first- and third-quarter moons, we get the relatively small tides known as neap tides.
Focal Plane:
- Where light from different directions comes into focus to create an image. In the eye the focal place is the Retina. Light rays that are not parallel, such as those of a nearby object do not converge into a single focus but they still bend at the lens.
Mercury Geology
-Also had lava that covered up craters -It has a mixture of heavily cratered and smooth regions like the moon. -Smooth regions are likely ancient lava flows. -The rembrandt basin is a large impact crater on Mercury -Hollows in a crater floor created by escaping gases. -It also has tectonics , long cliffs indicated that mercury shrank early in its history. The core retained more heat due to its iron composition through accretion and differentiation and when the core cooled off it probably shrunk creating those large cliffs.
Earth's surface How is earth's surface shaped by plate tectonics?
-Continental Drift -Seafloor Crust -Seafloor is recycled through a process known as subduction -North America has features that record the history of plate tectonics - tHE HIMALAYAS FORMED FROM A COLLISIONS BETWEEN PLATES - Red sea is formed where plates are pulling apart - The san andreas fault in california is a plate boundary -Motion of plates can cause earthquakes Plate Motions tells us past future layout of continents Hot spots: Hawaiian islands have formed where a plate is moving over a volcanic hotspot Many of Earth's features are determined by its size, rotation and distance from the sun.
Venus Geology
-Covered in a thick atmosphere that you cant see the surface, but we can map it out with radar. -Venus has impact craters but fewer than the moon, mercury or mars. -It has volcanoes, shield and strato The planets fractured and contorted surface indicates tectonic stresses. -Venus does not appear to have plate tectonics but entire surface seems to have rapaved earlier. -Little erosion
Jupiter
-Does not have a solid surface -It has many moons (about 79) (Io, Europa and Callisto, Ganymede) -These moons are large enough that we could call them dwarf planets if they orbited the sun -This set of moons is called Galilean Moons - Io: Volcanic -Europa: Icy crust with possible ocean subsurface -The remaining two have mysterious surfaces -Thin set of rings -Composed mostly of Hydrogen and Helium -Great Red Spot
Saturn
-Giant and Gaseous (Hydrogen and Helium) -Many Moons -Known for its spectacular Rings that can be seen -The rings look solid from a distance but they are actually small particles of dust and ice. Some are small as grain and others big as city blocks. -Second Largest Planet after Jupiter -Low Density and less massive than Jupiter despite being almost the same size - Titan: Cloudy moon, the only moon in the solar system with a thick atmosphere
Neptune
-Hydrogen, Helium, Hydrogen Compounds - Various Moons -Similar to Uranus but it has a more blueish color, but it has a higher density and more massive -Triton: Orbits its planet backwards, Triton once orbited the sun before being captured by Neptune
Role of Rotation:
-It can affect the magnetic field and atmospheric dynamics -Planets with slower rotation have less weather less erosion and a weak magnetic field -Planets with faster rotation have more weather more erosion and stronger magnetic field which will protect the atmosphere weather and erosion
Problems that affect astronomical observations
-Light pollution -Blurring of images by atmospheric pollution -The fact that most light forms do not reach the ground at all.
The Sun
-Made of 98% of hydrogen and Helium and 2% other elements -Contains about 99.8% of the solar system's total mass -Sun spots appear dark because they are a bit cooler than their surroundings - About the size of a Grapefruit
How did we arrive at a theory of solar system formation?
-Recall that a hypothesis can rise to the status of a scientific theory only if it offers a detailed physical model that explains a broad range of observed facts. -If a hypothesis fails to explain even one of the four features, then it cannot be correct. If it successfully explains all four, then we might reasonably assume it is on the right track.
Uranus
-Smaller than Jupiter and Saturn -Extreme Axis tilt, tipped on its side. This extreme tilt may have happened with extreme collisions during its formation. The extreme tilt causes the most extreme seasons in the solar system. -Composed of Hydrogen and its compounds and Helium -Many moons -Methane gives Uranus its pale green color -Not a solid surface -darker set of rings that are difficult to see
Nebular Theory
-States that our solar system formed from the gravitational collapse of a giant interstellar gas cloud - the solar nebula Kant and Laplace Close encounter hypothesis: A rival theory proposed that the planets formed from debris torn off the Sun by a close encounter with another star.
Earth
-Terrestrial Planet: Rocks and Metals - One moon -Temperatures are pleasant on Earth because the atmosphere contains just enough carbon dioxide and water vapor to maintain a moderate greenhouse effect.
Venus
-Terrestrial planet: Rocks and Metals -Nearly Identical in size to Earth -Strange Rotation: It rotates on its axis very slowly in the opposite direction to earth so days and nights are very long and the Sun arises in the west and sets in the east. -We know little of Venus due to its dense atmosphere full of clouds but we were able to map it out with a radar. -Geological evidence of past volcanic activity -It has valleys, mountains, and craters - Little Erosion - It has an extreme greenhouse effect which heats up its surface to high temperatures
Why are there two major types of planets?
-The key clue comes from their locations: - Terrestrial planets formed in the warm inner regions of the swirling disk:[INSIDE THE FROST LINE] -Jovian planets formed in the colder outer regions:[OUTSIDE FROST LINE] When the temperature is low enough, some atoms or molecules in a gas may bond and solidify.
Why does size of a planet affect geology?
-The size affects the cooling. -Large worlds have more erosion because gravity can retain more gases and liquid. -There is more volcanic and tectonic activity in large planets. -Hot planets have more difficulty retaining an atmosphere. -Planets far from the sun are too cold for rain limiting erosion -Planets with liquid water have the most erosion -Planets close to the Sun are too hot for rain, snow and ice so have less erosion
Atmospheres
-There is no clear upper boundary of an atmosphere. -Altitudes more than 100 km is considered space. -Small amounts of gas are present even above 300 km.
Chapter 5
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Earth is very gradually transferring some of its rotational angular momentum to the Moon, and as a result Earth's rotation is gradually slowing down
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How Interiors Get Hot
1. Accretion: It cause heat by depositing energy when planetesimals collide with a planet. The planetesimal generates kinetic energy when it approaches a forming planet, and when that planetesimal crashes it converts that kinetic energy into thermal energy adding heat to the planet. 2. Differentiation: When a planet undergoes differentiation (dense mass down/less dense mass up), it means that mass moves inward losing gravitational potential energy, and that movement creates friction which is then converted to thermal energy. 3.Radioactive Decay: When radioactive nuclei of isotopes decay they send off subatomic particles which then collide with other atoms heating them so in essence this converts some of the mass energy into thermal energy
How Interiors Cool Off
1. Convection:the process by which hot material expands and rises while cooler material contracts and falls, thereby transporting heat upward. Hot rock rises and cooler rock falls in a mantle convection cell. 2. Conduction:the transfer of heat from hot material to cooler material through contact; it is operating when you touch a hot object. Conduction carries heat through the lithosphere to the surface 3. Radiation: radiation (light) carries energy away and therefore cools an object. Planets lose heat to space through radiation; because of their relatively low temperatures, planets radiate primarily in the infrared. At the surface energy is radiated into space
Layers By Density
1. Core: The highest density material consisting of metals such as iron and nickel, reside in the central core 2. Mantle: Rocky material of moderate density. Surrounds the Core. (Silicon and Oxygen). It is a solid but a solid that over time it can convect 3. Crust: Lowest Density. Granite and Basalt. The lithosphere takes over the crust and part of the mantle that is completely frozen out. Lithosphere: defined by the strength of the rock We expect smaller worlds to have smaller cores
Controversies of the Mass extinction
1. Dinosaurs were already in decline 2. Volcanic eruption
Moon - Lunar Maria:
1. Early surface is covered with craters 2. Large impact crater weakens crust 3. Heat build up allows lava to well up to surface 4. Cooled lava is smoother and darker than surrounding areas.
Two key facts about Earth's orbit:
1. Earth needs no fuel or push of any kind to keep orbiting the Sun—it will keep orbiting as long as nothing comes along to take angular momentum away. 2. Because Earth's angular momentum at any point in its orbit depends on the product of its speed and orbital radius (distance from the Sun), Earth's orbital speed must be faster when it is nearer to the Sun (and the radius is smaller) and slower when it is farther from the Sun (and the radius is larger).
Interaction of Light
1. Emission: The process by which matter emits energy in the form of light. Light bulb 2. Absorption: The process by which matter absorbs radiative energy (light). 3. Transmission: The process by which light passes through matter without being absorbed. Glass or air transmits light. 4. Reflection/Scattering: Light that is reflected and bounces off matter. We call it reflection when light bounces in the same direction and scattering when the bouncing of radiative energy is more random. (A movie screen scatters light)
Universal Law of Gravitation
1. Every mass attracts every other mass through the force called gravity. 2. The strength of the gravitational force attracting any two objects is directly proportional to the product of their masses. For example, doubling the mass of one object doubles the force of gravity between the two objects. 3. The strength of gravity between two objects decreases with the square of the distance between their centers. We therefore say that the gravitational force follows an inverse square law. For example, doubling the distance between two objects weakens the force of gravity by a factor of 2 or 4.
how a star-forming cloud collapses under gravity
1. Heating 2. Spinning 3. Flattening
Compounds in the Solar Nebula
1. Hydrogen and Helium 2. Hydrogen compounds (icy) 3. Rocks 4. Metals Since hydrogen compounds were as much as three times more abundant as rock and metals this meant that there was more solid material beyond the frost line, so that is why we get bigger jovial planets. - Hydrogen and helium could not condense at any temperatures so the remained gaseous - In the inner part of the nebula it was too hot for rock and metal to condense so the stood gaseous until it cooled a bit down and they managed to condense. - It was too hot for hydrogen compounds to condense inside the frost line so they remained outside the frost line were temperature was lower and managed to condense, later on colliding with rocks and metals
What do Astronomers do with telescopes
1. Imaging: taking pictures of the sky 2. Spectroscopy: breaking light into spectra 3. Time Monitoring: Measuring how light output varies with time. Many astronomical objects vary with time. For example, some stars undergo sudden outbursts, and most stars (including our Sun) vary in brightness as starspots (or sunspots) cover more or less of their surfaces. Some objects vary periodically; for example, small, periodic changes in a star's brightness can reveal the presence of an orbiting planet Time monitoring allows us to carefully study such variations.
Processes that shape surfaces
1. Impact cratering 2. Volcanism 3. Tectonics 4. Disruption of a planet's surface by internal stresses 5. Erosion (wind, water or ice)
Light Effects on Atmosphere:
1. Ionization: removal of an electron 2. Dissociation: destruction of a molecule (ozone layer). X rays and UV light can ionize and dissociate molecules 3. Scattering: changes a photon direction Nitrogen molecules tend to scatter blue light more than red 4. Absorption: photon energy is absorbed. Molecules can absorb infrared light
Telescopes
1. Light Collecting Area: tells us how much total light it can collect at one time. A telescope's diameter tells us its light collecting area: A=pie(r)^2 - Diameter: photon basket - The largest telescopes have diameters of 10 meters - Hubble Telescope in space has a diameter of 2.4 meters Example: A 10 meter telescope is 5 times bigger than a 2 meter telescope so its light collecting area would be 25 times bigger (5^2) 2. Angular Resolution: The minimum angular separation that a telescope can distinguish. It is the smallest angle over which we can tell that two dots—or two stars—are distinct.A good telescope has good small angular resolution -the angular separation between two points of light depends both on their actual separation and on their distance from us - Angular resolution is limited because of interference, when beams of light interfere with one another
Why the geological time scale mostly shows more detail for the recent hundred million years:
1. Older rocks are much rare than young rocks 2. Old rocks that have been found have gone through transformations 3. Nearly all life was microscopic and those fossils are much harder to find.
Seismic Waves Types
1. P Waves: Pressure Waves (Primary) these waves travel fastest and are the first to arrive after an earthquake. They can travel through solid, liquid or gas. (Sound travels similarly) - Result from Compression 2. S Waves: Shear Waves (Secondary) S waves travel only through solids, because the bonds between neighboring molecules in a liquid or gas are too weak to transmit up-and-down or sideways forces. What do these waves tell us? The speed and direction of seismic waves depend on the composition, pressure, density, temperature and phase (liquid or solid) of the material they pass through. In an Earthquake P waves reach the opposite side of the earth, while S waves do not telling us that Earth has a liquid outer core.
Two distinct tails of the Comet
1. Plasma Tail: The Plasma tail consist of gas that is ionized by ultraviolet light and pushed by solar wind. The Plasma tail usually points directly away from the Sun. 2. Dust Tail: The Dust tail consists of dust particles that are unaffected by solar wind and instead pushed away by the pressure from the Sun. It also points away from the Sun but indirectly and it usually has a curve. in the direction the comet came from.
Proof that an Asteroid collision with Earth wiped out dinasours
1. The K-T layer: Iridium which is a major component of asteroids was found between a layer of the cretaceous period and a tertiary period. This layer also has shocked quartz which may have formed in extreme pressures caused by a collision. It has rock droplets, and it also has soot which arises from fire. 2. Big crater in the Yucatan peninsula: Large enough crater that hints the collision of a big asteroid capable of doing such damage The asteroid impacted Earth, hot debris showered Earth causing fire, ashes in the sky prevented high temperature creating hostile winter which killed up the food chain for dinosaurs etc... Dinosaurs went extinct about 65 million years ago.
Energy Levels
1. The lowest level is called ground state or level 1, where there is an energy of 0 electron volts. 2. Each of the higher levels are called excited states -The electron can change energy levels by gaining or losing the amount of energy that separates the levels. This is called ENERGY LEVEL TRANSITIONS. - If an electron is excited up to the point of ionization it can escape the atom leaving behind a positive charged ion. - the amount of energy separating the various levels gets smaller at higher levels.
To summarize it
1. The original cloud is large and diffuse, its rotation is slow and then begins to collapse 2. Because of conservation of energy the cloud heats up as it collapses (due to the gas particles falling inward and colliding creating kinetic energy). Then because of conservation of angular momentum the cloud starts to spin faster as it contracts. 3. Collisions between particles in the cloud flatten the cloud into a disk. These three steps result in a flattened, spinning disk with the mass and highest temp concentrated near the center. The formation of the spinning disk explains the orderly motions of our solar system today. The fact that collisions in the disk tended to make orbits more circular explains why the planets in our solar system have nearly circular orbits.
Source of atmospheric Gases
1. Volcanic Outgassing 2. Vaporization 3. Surface ejection
Basic Properties of a Wave:
1. Wavelength: Peaks and troughs 2. Frequency: The rate at which peaks pass by any point. (Measured in units of 1/s called hertz or cycles) - For example, if the leaf in the pond bobs up and down three times each second then it means the waves have a frequency of 3 cycles per second. 3. Speed: The speed of the wave tells us how far their peaks travel across. The speed essentially tells us how fast the energy travels from one place to another.
The theory of Evolution is based on two facts
1. any population has the potential to produce more offspring than it can support which means there is competition of survival 2.individuals will always vary in traits Conclusion: Some individuals were better at reproducing and surviving than others and these individuals will be able to pass on their advantageous traits
What are the requirements for surface habitability?
1.A distance from the Sun that is great enough to allow water vapor to condense as rain and make oceans, but not so far that all the water freezes. 2. Volcanism that released trapped gases from the interior, including water vapor and carbon dioxide, to make the atmosphere and oceans 3. Plate tectonics that support a climate-regulating carbon dioxide cycle 4. A planetary magnetic field that protects the atmosphere from the solar wind
There are three basic requirements for a global magnetic field:
1.An interior region of electrically conducting fluid (liquid or gas), such as molten metal. 2.Convection in that layer of fluid 3. At least moderately rapid rotation. In general you need conducting metals and an orbit
Three Different types of Spectra
1.Continuous 2. Emission Line 3. Absorption Line
Four criteria for the success of a solar system formation theory:
1.It must explain the patterns of motion discussed 2.It must explain why planets fall into two major categories:terrestrial planets and jovian planets 3. It must explain the existence of huge numbers of asteroids and comets and why these objects reside primarily in the regions we call the asteroid belt, the Kuiper belt, and the Oort cloud. 4.It must explain the general patterns while at the same time making allowances for exceptions to the general rules, such as the odd axis tilt of Uranus and the existence of Earth's large Moon.
Jovian Planets
1.Jupiter 2.Saturn 3.Uranus 4.Neptune -Bigger Planets -Composed of hydrogen and hydrogen compounds -Gaseous -Lower density -They have lots of moons -colder -further away
If Polaris, the North Star appears 38 degrees above your northern horizon, what is your latitude?
38 degrees north
What would the angle between the Sun and the southern horizon at noon on the day of vernal equinox in New York, NY (40 degrees N) be?
50 degrees
What would the angle between the Sun and the southern horizon at noon on the day of summer solstice in Seattle, WA (47 degrees N) be?
66.5 degrees
Refraction
A change in direction in which light is traveling. Waves of light slow down when they hit the glass because light travels more slowly through denser matter. - Can cause parallel light rays to converge into a focus.
Field
A field is an abstract concept used to describe the strength of force that a particle would experience at any point in space. Earth creates a gravitational field that describes the strength of gravity at any point in space. The strength of the field decreases when the distance increases. Electricity and Magnetism can also create fields called electric and magnetic fields.
Meteors and Meteorites
A meteor is only a flash of light caused by a particle of dust or rock entering our atmosphere at high speed, not the particle itself. (THE TRAIL OF LIGHT THAT A METEORITE LEAVES BEHIND) A meteorite is a rock from space that lands on Earth Meteorites often contain elements such as iridium that are very rare in Earth rocks Meteorites often contain elements such as iridium that are very rare in Earth rocks They are important because many of them remain much as they were when they first formed, some 4.5billion years ago.
Planetary Temperature:
A planet's surface temperature is determined by the balance between energy from sunlight it absorbs and energy of outgoing thermal radiation. - A planet's distance from the sun determines the total amount of incoming sunlight - A planet's reflectivity or albedo is the fraction of incoming sunlight it reflects - Planet's with low albedo absorb more sunlight, leading to hotter temp.
The first quarter moon rises.. A) at about noon B) at sunset C) at sunrise D) at about midnight E) during the second week of each calendar monthA) at about noon
A) at about noon
To summarize Accretion and Planetesimals
Accretion began with solid microscopic particles that condensed from the gas of the solar nebula. This particles orbited the forming Sun the same way and these particles collided with other particles (like gentle touches) until the sticked together forming bigger and much bigger particles. As they grew in mass they began to attract each other with gravity growing into bigger pieces forming planetesimals which are the building blocks of terrestrial planets. Only the largest planetesimals avoided being shattered and could grow into terrestrial planets.
What happens when the comet loops around the sun?
After the comet loops around the Sun, vaporization ends and the comet loses its tail looking once again as a dirty snowball until it loops around the Sun again (or sometimes it may never loop around).
Speed of light
All light travels with a speed of 300,000 km/s - The longer the wavelength, the lower the frequency, and the shorter the wavelength, the higher the frequency.
Central to the HELIOCENTRIC model is the assertion that the observed motion of the planets and the Sun are the result of...
All planets orbit around the Sun
How do we know the age of the solar system?
Although the oldest Moon rocks are older than the oldest Earth rocks, the rocks must still be younger than the Moon and Earth as a whole. In fact, their age tells us that the giant impact thought to have created the Moon must have occurred more than 4.4 billion years ago. But how do we determine when the planets first began to form? To go all the way back to the origin of the solar system, we must find rocks that have not melted or vaporized since they first condensed in the solar nebula. Meteorites that have fallen to Earth are our source of such rocks. Many meteorites appear to have remained unchanged since they condensed and accreted in the early solar system. Careful analysis of radioactive isotopes in these meteorites shows that the oldest ones formed about 4.56 billion years ago, so this time must mark the beginning of accretion in the solar nebula. Because the planets apparently accreted within about 50 million (0.05 billion) years after that, Earth and the other planets had formed by about 4.5 billion years ago. In other words, the age of our solar system is only about a third of the 14-billion-year age of our universe.
Acceleration:
An object has acceleration if an object's velocity is changing in any way, whether in speed or direction or both.
Newton's first law of motion: It essentially restates Galileo's discovery that objects will remain in motion unless a force acts to stop them:
An object moves at a constant velocity unless a net force acts to change its speed or direction. That is why a space ship needs no fuel.
Momentum
An object's mass x velocity. An object's momentum can only change if a net force acts upon it
Volcanism
Any activity that includes the movement of magma toward or onto Earth's surface. It happens when magma finds a path through the lithosphere, and when volcanism happens and magma is discharged, gases are also brought into the atmosphere. When lava dries up, new land is created. - Runny Lava makes flat lava plains - Slightly thicker lava makes shield volcanoes - Thick lava steep stratovolcanoes
How did we get our water?
Asteroids that formed beyond the frost line contain some water and it may be possible they are the ones that brought water to Earth as they crashed with us providing us with water and carbon rich ingredients making Earth a habitable place.
Second Law
Astronomically, Newton's second law explains why a large planet such as Jupiter has a greater effect on asteroids and comets than does a small planet such as Earth [Section 12.2]. Jupiter exerts a stronger gravitational force on passing asteroids and comets, and therefore sends them scattering with a greater acceleration.
Earth
Atmosphere of about 10 km thick Consists mostly of molecular nitrogen 78% and oxygen 21% Nitrogen: Gives us our blue sky Oxygen: Lets us breathe CO2: Creates our Greenhouse warming
Why liquid water cannot survive on the surface of Mars?
Atmospheric pressure is too low, and water may boil
Average Density
Average Density= total mass/total volume
What statement is false? A) The geocentric model of the universe holds that Earth is at the center, and everything else moves around it B) Copernicus was the first to propose that Earth moves around the Sun C) Galileo's observations of phases of Venus supported none-obvious view of Copernicus that all planets revolve around the Sun D) Though based on a wrong idea, Ptolemy's model was very practical for a long time E) Using his laws of motion and gravity, Newton was able to explain and prove Kepler's laws
B) Copernicus was the first to propose that Earth moves around the Sun
Atom
Basic unit of matter consisting of a nucleus made from protons and neutrons surrounded by electrons
Why Big Worlds Are Round
Because of gravity
Orbital Resonance explains why planets did not form between Mars and Jupiter
Because of orbital resonance no planets formed between Mars and Jupiter because the orbital resonance caused by Jupiter sent planetesimals with potential to form out of their orbits and sometimes sent planetesimals to crash with one another.
If the center of Earth is its hottest part, why is it solid?
Because of the Pressure
Could there be life in the outer solar system?
Beyond Mars, the cold temperatures of the outer solar system make it unlikely that we could ever find surface liquid water.
Kuiper Belt
Beyond the orbit of Neptune Most comets are in here.
What do Martian and Venetian atmospheres have in common?
Both atmospheres are composed mainly of carbon dioxide.
energy
Broadly speaking, what can make matter move. The three basic types of energy are kinetic, potential, and radiative.
Nucleus:
Built from Protons and Neutrons and although it is smaller than the atom it contains nearly all the mass.
How do we measure the age of a rock?
By radiometric dating. Radio dating relies on careful measurement of the rocks atoms and isotopes. The key to radiometric dating is that some isotopes are radioactive which is just a fancy way of saying that their nucleus undergo some type of change (decay) with time such as breaking into two pieces or having a neutron turn into a proton.
Saturn is on average 10 AU from the Sun. What is the approximate orbital period of Saturn?
C) 32 years
The Figure 1 illustrates Kepler's three laws. In which box is the comment correct? A) The speed of a planet is the same throughout the orbit B) Planets move by elliptical orbits with Sun in the center C) As greater the semi-major axis as longer it takes for a planet to complete the orbit around the Sun
C) As greater the semi-major axis as longer it takes for a planet to complete the orbit around the Sun
Eunice Newton:
CO2 gas warms more in sunlight than other gases. "an atmosphere of that gas would give to our earth a high temp"
Ground Sites for Astronomical Observations
Calm/high/dark/dry Three sites: 1. Mauna Kea 2. La Palma, Canary Islands 3. Paranal Observatory, Chile
Where in inner solar system could one find Calorie Basin?
Calorie Basin
When the huge polar caps on Mars form every winter, what they mainly made of?
Carbon Dioxide Ice
Net Force and Momentum
Changing an object's momentum means changing its velocity, as long as its mass remains constant. A net force that is not zero therefore causes an object to accelerate. Conversely, whenever an object accelerates, a net force must be causing the acceleration.
clouds and precipitation
Clouds are highly reflective so they send infrared out of earth and they are also made out of water vapor so they act as a greenhouse effect.
What could be responsible for irregularities in present planetary orbits?
Collisions
Velocity
Combination of speed and direction. Ex. An object going 100km/h due North
Comets and Meteor showers
Comets also eject sand to pebble size particles that are too big to be affected by Solar Wind or Sunlight. These particles form a third tail that follows the comet's trail and creates what we know as meteor showers. Meteors can be seen on any clear night but can be seen even more when Earth passes through a comet's orbit.
Composition of Comets
Comets are basically dirty balls of snow, made out of chunks of ice with rocky dust and other complex chemicals. Spectra revealed that Comets formed in the outskirts of the frost line given its composition of water and hydrogen compounds.
Photons
Definition: An individual particle of light, characterized by a wavelength and a frequency. - We say that light comes in "individual" pieces called photons that have properties of both waves and particles. - Each photon of light carries a specific amount of radiative energy
Dwarf Planet
Dwarf planets can be either asteroids or comets that are large enough to be round. Pluto was considered a planet before being considered a Dwarf Planet. Before being named a dwarf planet scientists observed that Pluto orbited near the the middle of the Kuiper Belt and it looked more like a comet.
Jupiter's Potentially Habitable Moon
Europa is considered the strongest candidate for potential life. The ice and rock from which Europa formed undoubtedly included the chemical ingredients necessary for life, and Europa's internal heating (primarily due to tidal heating) is strong enough to power volcanic vents on its seafloor.
Telescopes
Everything used to see far away
How much earlier might life have arisen?
Evidence from ancient mineral grains* indicates that Earth may already have had oceans as early as about 4.3 billion years ago, suggesting at least the possibility that life could have existed at that time. But remember that Earth was undergoing heavy bombardment which most likely vaporized the oceans and wiped the life out of it, but surviving microbes may have survived deep in the environment.
The theory of Evolution
Evolution: species change with time (an observed fact by fossil records) The theory of evolution explains why and how evolution works.
Lunar eclipses happen more often than solar.
False
Why do comets grow tails?
Far from the sun comets are just like asteroids but ast they get closer to the Sun the Sun heats the ice, turning it into gas giving it its flashy look.
Newton's Second Law of Motion
Force equals mass times acceleration We can also use Newton's second law to clarify the difference between mass and weight.
What phase Moon is rising at sunset?
Full Moon
Newton's legacy
He quantified the laws of motion and gravity, conducted crucial experiments regarding the nature of light, built the first reflecting telescopes, and invented the mathematics of calculus.
Wavelength does not depend on Amplitude.
Higher amplitude just means the light is more intense.
Tycho Brahe's greatest contribution to Astronomy was
His 20 years of precise observations
Convection Cells
Hot rock deep in the mantle slowly rises transferring all its heat until it cools down and falls down again, and this process creates convection cells where convection happens. Mantle convection stops at the base of the lithosphere due to its rigidness, so then the heat is transferred through conduction, and then the heat escapes to space through radiation.
thermal radiation
Hotter objects emit more light at all frequencies and emit photons with a higher average energy. Molecules in warm objects emit infrared light which is why we associate heat with infrared.
How does gravity cause tides?
In most places, tides rise and fall twice each day. We can understand the basic cause of tides by examining the gravitational attraction between Earth and the Moon.
Lithosphere
In terms of rock strength, Earth's outer layer is composed of the lithosphere, which is relatively rigid and cool rock (crust and frozen mantle). It floats on warmer rock beneath. Smaller worlds tend to have thicker lithospheres. Earth and Venus have small lithospheres, while Mercury and Mars and the Moon have huge lithosphere A thin Lithosphere is brittle and may break A thick Lithosphere is rigid and strong and may prohibit the passage of molten rock which may reduce or restrict volcanic activity, making the formation of mountains and reshaping of the surface much harder.
If an observer sails north toward increasing latitude (from Florida to Maine along Atlantic coast), the number of circumpolar stars (stars that never go below the horizon) would..
Increase
Why do some planetary interiors create magnetic fields?
Interior heat can help create a global magnetic field. A magnetic field is the region surrounding a magnet in which it can affect other magnets or charged particles.
Which of the Galilean satellites is the densest and most geologically active?
Io
Jupiter's Moons (Galilean Moons)
Io: Volcanic moon Europa: Icy crust moon Ganymede: Biggest Moon in the solar system Calisto: Heavily Cratered Ice ball
What does the study of astronomical spectra tells us?
It allows us to learn what distant objects are made of
Continuous Spectra
It is called continuous because there are no gaps in the rainbow, the spectrum shows a continuous and smooth rainbow of light. - The graph of the spectrum shows the intensity of the light at each wavelength. The peak intensity depends on the temperature of the light bulb or the object that is radiating light If we make the light bulb hotter we would see that peak move to shorter wavelengths. Also called the thermal radiation spectrum because of its temperature dependence. Rocks, people and stars also produce thermal radiation spectrum. Thermal Radiation: Light that has a continuous spectrum that depends only on the objects temperature. As an object cools down it shifts from shorter wavelengths to longer wavelengths. - Higher temperature objects emit more light - Higher temperature have shorter wavelength The sun Emits white light because it emits almost equally over all the colors of the visible light rainbow Since these curves show the intensity of light per unit area the total light output of other stars and objects depends on its size
Emission Spectra
It is produced by thin or low density clouds of gas. Instead of a rainbow we see. - The wavelengths of the emission lines are determined by the energy levels of hydrogen atoms and photons emitted when electrons drop to lower energy levels Hydrogen Emission: Red has highest intensity - The atoms in any cloud of gas are always colliding with one another and when they do energy is being transferred in some of the collisions which bump electrons to higher energy levels. Still electrons can't remain in higher energy levels for long so they always fall back to the ground state. When they fall down it loses energy but the energy doesn't just disappear and it often goes into emitting a photon of light. The emitted photon must have the same energy that the electron lost so it must have an specific wavelength and frequency. - As long as the cloud of gas remains moderately warm, the atoms will continue to collide and bouncing electrons which will transit from high energy levels to low energy levels emitting photons of light which emits light visible as emission lines. The bright emission lines correspond to the downward transition of electrons. The specific set of lines we see in an emission line spectra depends on the composition of the cloud and its temperature. At hotter temperature there will be more collisions of atoms which emit more photons of light. We can learn the temperature of an object from its spectrum and sometimes just by its color
Refracting Telescope
It operates much like an eye, using transparent glass lenses to collect and focus light. - Earliest telescopes are refracting telescopes, such as Galileo's - The world's largest refracting Telescope has a diameter of 1 meter and a length of tube of 19.5 meters (University of Chicago)
Pluto
Its orbit is much more elliptical and inclined than that of the other 8 planets, and sometimes it comes close to Neptune.
What would happen to Earth's temp if Earth were more reflective?
Its temperature would go down
measurement of energy
Joules. We are more interested in finding the rate of energy and not the total amount. The rate of energy flow is called power, which we measure in units called watts. A power of 1 watt means an energy flow of 1 joule per second: 1 watt=1 joule/s
Stars do not twinkle
Just like water bent on pools, stars do not twinkle, its light is bent by air turbulence which may seem as it is twinkling. There is more twinkling on windy days when near the horizon.
Kilograms
Kilograms are a unit of mass, not of force.
Comets
Left over of icy planetesimals (outside frost line)
Asteroids
Left over of rocky planetesimals (inside the frost line)
X-Rays
Light wave right before the Ultraviolet
Ultraviolet Light
Light wave right before the blue wave in the spectrum
Radio Waves
Light waves with the longest wavelength and shortest frequency
Infrared Light
Light with the wavelengths beyond the red
Spinning
Like an ice skater as he spins, when he shrinks his arms his angular momentum and speed increases, so as the solar nebula shrunk in size it rotated faster and faster. This increase in rotation rate represents conservation of angular momentum in action The rotation of the cloud may have been imperceptibly slow before its collapse began, but the cloud's shrinkage made fast rotation inevitable. The rapid rotation helped ensure that not all the material in the solar nebula collapsed into the center: The greater the angular momentum of a rotating cloud, the more spread out it will be.
What surface features have formed on Mercury when the planet's interior cooled and shrank? A) Jumbled terrain B) The highlands C) Maria D) Lobate scarps E) Sinuous rilles
Lobate Scarps
There is undeniable evidence that liquid water once run over the surface of Mars. What about Mars must have been different?
Mars had higher surface temperature and heavier atmosphere.
Transparent and Opaque Materials
Materials that transmit light are called transparent and materials that absorb light are called opaque.
Atmospheric Pressure
Measured in Bars - Pressure and Density decrease as we go up because the weight of overlying layers is less.
Of the inner planets, which has the most cratered surface?
Mercury
Correct order of Solar System
Mercury Venus Earth Mars Asteroids Jupiter Saturn Uranus Neptune Pluto
Order of planets from the sun
Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto, Eris
Chemical Footprints
More highly charged ions will be present at higher temperatures
Impact cratering
Most cratering happened soon after the solar system formed. HEAVY BOMBARDMENT Craters are about 10 times wider than the objects that made them. Small craters greatly outnumber large ones. Small cratered areas are called Maria (look like seas)
natural selection
Nature tends to select traits that enhance survival and reproduction. This model of evolution by natural selection explains why we see changes in fossil records and observed characteristics of living species.
What is the name of only planet whose density is less than density of water?
Neptune
Newton and Kepler
Newton resolved the debate by showing that Kepler's laws are consequences of the laws of motion and the universal law of gravitation. In particular, with the aid of the mathematics of calculus that he invented, Newton showed that the inverse square law for gravity leads naturally to elliptical orbits for planets orbiting the Sun (with the Sun at one focus), which is Kepler's first law. As we've seen, Kepler's second law (a planet moves faster when it is closer to the Sun) then arises as a consequence of conservation of angular momentum. Kepler's third law (average orbital speed is slower for planets with larger average orbital distance) arises from the fact that gravity weakens with distance from the Sun. Newton also discovered that he could extend Kepler's laws into a more general set of rules about orbiting objects.
Objects Orbit Their Common Center of Mass
Newton showed that two objects attracted by gravity actually both orbit around their common center of mass—the point at which the two objects would balance if they were somehow connected - When one object is more massive than the other, the center of mass lies closer to the more massive object.
Newton
Newton's sudden insight delivered the final blow to Aristotle's view. By recognizing that gravity operates in the heavens as well as on Earth, Newton eliminated Aristotle's distinction between the two realms and brought the heavens and Earth together as one universe. This insight also heralded the birth of the modern science of astrophysics (although the term wasn't coined until much later), which applies physical laws discovered on Earth to phenomena throughout the cosmos.
What is light?
Newton's work tells us something about the nature of color, but it still does not tell us exactly what light is.
What is the most abundant gas in Earth's atmosphere?
Nitrogen
Geyser in Triton
Nitrogen/Liquid Nitrogen
Neutron
No Charge. Built from three quarks
Electromagnetic Spectrum
Notice that wavelength increases as we go from gamma rays to radio waves (left to right), while frequency and energy increase in the opposite direction (right to left).
Atomic Number
Number of protons in nucleus
Meteorites
Oldest meteorites are 4.55 billion years old Planets probably formed 4.5 billion years ago
Jim lives in a place where once a year, on the day of Summer Solstice the Sun is directly overhead. Where does Jim live?
On Tropic of Cancer
unbound orbits
Orbits on which an object comes in toward a large body only once, never to return; unbound orbits may be parabolic or hyperbolic in shape.
bound orbits
Orbits on which an object travels repeatedly around another object; bound orbits are elliptical in shape.
Electrons
Particles with Negative Charge. Gives the atom its size.
heavy bombardment
Period of heavy collisions of bombardment where most of the planetesimals impacted on planets leaving behind craters. It tailed the the formation of the Solar System. Most of the craters on the moon and other planets date from this period. Water may have come to Earth by way of icy planetesimals
What discovery made by Galileo proved the heliocentric point of Copernican model?
Phases of Venus
What does the small size of a planet represent?
Planets with small sizes cool of more rapidly than bigger planets. So generally speaking, planets like the moon and Mercury which are cooled off means that their loss of internal heat has left them without volcanic and tectonic activity restricting them from geological processes. Small size planets also mean that they have less erosion and that small planets lack of having an atmosphere. Due to its small size their gravitational force is weaker so gravity is not able to hold gases and liquids enough to retain a good atmosphere. Since these planets cant hold gas for much time The lack of geological activity is evident because they are heavily cratered and have the ancient marks of heavy bombardment. Still both Mercury and Moon show that they had hot interiors due to the ancient marks that resemble volcanic activity.
Pluto's moons
Pluto has 5 moons. The largest moon is Charon which has a relatively low density compared to Pluto which hints that Pluto may have gotten its moon the same way we did. A big collision may have plunged away the low density outer layers creating a ring and then accreting into Charon. This impact also explains why Pluto rotates on its side.
Protons
Positive Charge. Built from three quarks
Types of Meteorites
Primitive: They are considered primitives in the sense that they are remainings from the birth of our solar system. Unchanged since they first accreted. Subtypes: 1. Carbon rich: composed of rock, large amounts of carbon and sometimes some compressed water. 2. Stony: mostly composed of rocky minerals and some flakes of metal. + Primitive meteorites are important because they tell us how and when the solar system formed. Processed: We call meteorites processed when they first belonged to a larger object and were processed into another form. Subtypes: 1. Metal-Rich: composed mostly of iron and nickel. Resemble the core. High Density 2. Rocky: Composed of rock and resemble the mantle and crust. resemble basalt. Low density +Processed meteorites, especially metal rich meteorites are important because they tell us how large object underwent differentiation and how their core must have looked like. Rocky processed meteorites are also important because since they resemble those rocks which are formed by volcanic activity they tell us that large asteroids may have undergone some type of volcanism and have lava flows within them
Absorption Line Spectra
Produced when a thin cloud if gas lies between us and a source of light like a light bulb and the cloud is cooler than the light source. - For example if there is a thin cloud of hydrogen between us and a light bulb then the spectrum shows the rainbow of light from the light bulb but with interrupted by dark absorption lines of particular wavelengths. - The Intensity graph shows these absorption lines as Dips inside the smooth curve. Because the wavelengths of the absorption lines are determined by the energy levels of hydrogen atoms they appear at the same wave lengths which we would see emission lines if we looked at the cloud without a light source behind it. Both the absorption lines (dips) and the emission lines represent the same energy level transitions just that in opposite directions. Since a light-bulb is continuously emitting light creating a rainbow of color, the light continuous to heat up the cool cloud of gas which is absorbing the energy and transitioning its electrons from lower levels of energy to higher energy levels, and this is why dark absorption lines occur at the same wavelengths as emission lines - We would see more lines if there were additional elements, because every chemical element and ion molecule has a unique set of spectral lines Absorption line Spectra tells us that we are looking at a hot source of light through a cooler gas.
Atmospheric History of Mars
Recall that Mars has an axis tilt similar to that of Earth, which means it undergoes seasonal changes. However, while axis tilt is the only important influence on Earth's seasons, Mars's seasons are also affected by its orbit. Mars's more elliptical orbit puts it significantly closer to the Sun during southern hemisphere summer (and farther from the Sun during southern hemisphere winter), giving its southern hemisphere more extreme seasons—that is, shorter, warmer summers and longer, colder winters—than its northern hemisphere. Martian Winds The strong winds associated with the seasonal cycling of carbon dioxide gas can initiate huge dust storms, particularly when the more extreme summer approaches in the southern hemisphere. At times, the Martian surface becomes almost completely obscured by airborne dust. As the dust settles out, it can change the surface appearance over vast areas (for example, by covering dark regions with brighter dust); such changes fooled astronomers of the past into thinking they were seeing seasonal changes in vegetation. Martian Winds cause Dust Devils Mars's climate appears to have undergone at least two types of long-term climate change: (1) changes that recur over time due to a changing axis tilt and (2) an even longer-term change that transformed Mars from a much warmer, wetter planet to the cold desert we see today. Lack of Mars core convection means that there was no magnetic field and in response no magnetosphere to protect it from solar winds which may have stripped away Because Mars lacks an ultraviolet-absorbing stratosphere, atmospheric water molecules would have been easily broken apart by ultraviolet photons. It was big enough for volcanism and outgassing to release water and atmospheric gas early in its history, but too small to maintain the internal heat needed to keep this water and gas. As Mars's interior cooled, its volcanoes quieted and released far less gas, while its relatively weak gravity and the loss of its magnetic field allowed existing gas to be stripped away to space.
What Jupiter and Saturn have in common?
Rings Both have belt and zone circulation Both emit more energy than they absorb from the sun Liquid metallic hydrogen in their interiors.
Asteroids: (starlike)
Rocky small planetesimals Ceres: It was first considered as a planet before being considered an asteroid, (the largest asteroid). Ceres has a larger proportion of ammonia-bearing compounds than we would expect under the assumption that it formed inside the frost line. Ceres is also largely composed of water Smaller asteroids are more common than larger Asteroids are cratered and not round (except for ceres) but still they can have moons Some large asteroids have their own moon = Asteroid Ida has its own moon Dactyl asteroid belt between Mars and Jupiter Why are asteroids beyond Jupiter's orbit? Ice could form in the outer system An asteroid's shape depends largely on the strength of its gravity. Only large asteroids have gravity strong enough to have molded them into somewhat spherical shapes Size of an asteroid can be estimated through careful measurements of an asteroid's brightness, which depends on its size, distance, and reflectivity.For example, if two asteroids at the same distance have the same reflectivity, the one that appears brighter must be larger in size. We can determine an asteroid's distance from its position in its orbit. Reflectivity can be measured by comparing the asteroid's visible brightness, which comes from the sunlight it reflects, to its infrared brightness, which depends on the asteroid's temperature and hence tells us how much sunlight it absorbs. Astronomers can then use the reflectivity and distance to calculate the asteroid's size. Measuring an Asteroid's mass and Density: The most direct way to measure a distant object's mass is to observe its gravitational effect on another object, and to date this is possible only for the relatively few asteroids visited by spacecraft and for those that have smaller asteroids as tiny orbiting "moons." If it has a moon, we can find its mass by measuring its orbital period and distance Measuring the orbit of the asteroid's moon tells us and asteroid's mass Mass and size tells us an asteroid's density We can know the composition of asteroids by measuring their density. We can know if an asteroid is a thick chunk of rocks or just a pile of rubble held together by gravity. By measuring the Spectra of Asteroids we can know more in depth their composition and chemical constituents. We have concluded that asteroids are mostly made up of rocks and metals because they accreted inside the frost line. Some asteroids near the outskirts of the belt contain water and are rich in carbon which tells us they condensed in much cooler areas (not close to the frost line)
Visible Light: Warming the Surface and Coloring the Sky
Scattering: 1. First, scattering makes the daytime sky bright, which is why we can't see stars in the daytime. Without scattering, sunlight would travel only in perfectly straight lines, which means we'd see the Sun against an otherwise black sky, just as it appears on the Moon. Scattering also prevents shadows on Earth from being pitch black. On the Moon, shadows receive little scattered sunlight and are extremely cold and dark. 2. Second, scattering explains why our sky is blue. Gas molecules scatter blue light (higher energy) much more effectively than red light (lower energy). When the Sun is overhead, this scattered blue light reaches our eyes from all directions and the sky appears blue
Building the Jovian Planets
Since jovian planets were bigger and had more mass they had more energy and force of gravity to attract more compounds which allowed them to capture more of the hydrogen and helium from the Solar Nebula, and this added gas allowed them to attract even more gas. - Ultimately they captured so much gas that they did not resemble the icy seed beginnings they came from, and ended up being composed of mostly gases. Jovian Planets came to be surrounded by their gas disks which spinned in the same direction of the planet. Moons that accreted from ice-rich planetesimals within these disks ended up with nearly circular orbits going in the same direction as their planets.
Lunar Maria
Smooth dark regions of the moon? Why are they smooth and not heavily cratered like the highlands. Well during the heavy bombardment the Moon was heavily cratered and some impacts were violent enough to have ruptured through the lithosphere, although there was no molten rock to
Mars
Terrestrial Planet: Rocks and metals - 2 Moons (very small and captured) - Larger than Mercury and the Moon but smaller than Earth (half its diameter) - Great Evidence of Geological activity: Tharsis Bulge: Three big volcanoes Valles Mariners the canyon Mons Olympus - Polar caps made of frozen carbon dioxide (dry ice) - There is a presence of fluvial features, dried up river beds and rocks that appear to have been formed in water. -Major flow of liquids may have disappeared billions of years ago but there may still be water flowing undergrounds. - Low air pressure, exposure to deadly ultraviolet rays
In the northern hemisphere we have seasons with cooler winters and warmer summers. What is the cause of these changes in average temperature between the seasons?
The Earth's axis of rotation is tilted with respect to the plane of the solar system. Although the tilt does not change as the Earth revolves around the Sun this still leads to the variation in angle of sunlight resulting in the warmer summer and colder winter in the northern hemisphere.
Sun
The Sun appears distorted at sunset because of how light bends in Earth's atmosphere. - light from the lower portion of the Sun passes through more atmosphere and therefore bends slightly more than light from the upper portion.
Rest Wavelength
The absence of any Doppler Shift
Frost line
The boundary in the solar nebula beyond which ices could condense (Outside Frost Line)(Jovian Planets); only metals and rocks could condense within the frost line.(Inside Frost Line)(Terrestrial Planets).
Planetesimals
The building blocks of planets, formed by accretion in the solar nebula. Planetesimals of rock and metal formed as particles collided with each other and gravity assembled them together, later creating what we know today as planets.
Coriolis Effect:
The effect due to rotation that causes air or objects on a rotation surface or planet to deviate from straight line trajectories. Planetary rotation affects global wind patterns through the Coriolis effect Conservation of Angular momentum causes a ball's apparent path on a spinning platform to change direction. - In general: air moving from a pole to the equator is going slower than Earth's rotation and begins to lag behind Air moving from the equator to the pole moves faster than the land it's moving toward and travels ahead of Earth's rotation. Conservation of angular momentum causes large storms to swirl. Direction of circulation of storms depends on hemisphere The Coriolis effect operates to some extent on all planets. Its strength depends on a planet's size and rotation rate: Larger size and faster rotation both contribute to a stronger Coriolis effect.
What does it mean that Jupiter has "differential rotation"?
The equator of Jupiter rotates faster than its poles
condensation
The formation of solid or liquid particles from a cloud of gas.
Planets are relatively cool and emit infrared light
The hot upper layers of stars and the sun emit ultraviolet rays and x-rays
Focus
The point at which light rays that were initially parallel converge. This explains why distant stars appear as points of light - Light rays that enter the lens farther from the center are bent more, and those who enter straight continue straight.
Law of conservation of energy
The principle that energy (including mass-energy) can be neither created nor destroyed, but can only change from one form to another.
First Law of conservation of momentum
The principle that, in the absence of net force, the total momentum of a system remains constant.
Visible Light
The reddest red that our eyes can see has only about twice the wavelength of the bluest blue
Doppler Effect and wavelengths of Light
The same as sound waves, when light gets closes to an object it gets bunched up. Because shorter wavelengths of visible light are bluer the Doppler Shift of an object coming toward us is called a blue shift. If an object is moving further away, it is called Red shift, since it has longer wavelengths and longer wavelengths are redder. The larger the shift the faster the object is moving The Doppler Shift tells us only the speed of an object that is directed towards or away from us. If it is directed across our line of sight it will not measure any speed at all. If an object is moving diagonally away from us then the Doppler shift will tell us the part of the object's speed away from us but not the speed across our line of sight. The Doppler effect can also tell us information about the motion within the object. As an object rotates, light from the part of the object moving toward us will be blue shifted and the light moving away from us will be red shifted, and light from the center won't be shifted at all.
Tidal Friction
The slight misalignment of the tidal bulges with the Earth-Moon line causes two important effects. First, the Moon's gravity always pulls back on the bulges, slowing Earth's rotation. Second, the gravity of the bulges pulls the Moon slightly ahead in its orbit, adding orbital energy that causes the Moon to move farther from Earth. These effects are barely noticeable on human time scales—for example, tidal friction increases the length of a day by only about 1 second every 50,000 years*—but they add up over billions of years. Early in Earth's history, a day may have been only 5 or 6 hours long and the Moon may have been one-tenth or less its current distance from Earth. These changes also provide a great example of conservation of angular momentum and energy: The Moon's growing orbit gains the angular momentum and energy that Earth loses as its rotation slows.
Flattening
The solar nebula flattened into a disk. This flattening is a natural consequence of collisions between particles in a spinning cloud. A cloud may start with any size or shape, and different clumps of gas within the cloud may be moving in random directions at random speeds. These clumps collide and merge as the cloud collapses, and each new clump has the average velocity of the clumps that formed it. The random motions of the original cloud therefore become more orderly as the cloud collapses, changing the cloud's original lumpy shape into a rotating, flattened disk. Similarly, collisions between clumps of material in highly elliptical orbits reduce their eccentricities, making the orbits more circular.
Heating
The temperature of the solar nebula increased as it collapsed. Such heating represents energy conservation in action. As the cloud shrank, its gravitational potential energy was converted to the kinetic energy of individual gas particles falling inward. These particles crashed into one another, converting the kinetic energy of their inward fall to the random motions of thermal energy. The Sun formed in the center, where temperatures and densities were highest.
The geological time scale
The time scale used by scientists to describe major eras in Earth's past.
What is the age of the rock?
The time since the rock solidified and atoms locked together
Orbital Energy stays constant
The total orbital energy of a planet stays constant throughout its orbit, because its gravitational potential energy increases when its kinetic energy decreases, and vice versa.
Torque
The type of force that can change an object's angular momentum. "Twisting Force"
The "Top" of an Atmosphere
There is no clear boundary between the atmosphere and space above, because pressure and density decrease gradually with increasing altitude.
Net Force and Constant Velocity
There is not net force when an object moves at a constant velocity. A change in momentum only occurs when the net force is not Zero.
Why are asteroids concentrated in a belt?
They are concentrated in a belt because of gravity effects caused by Jupiter. Planetesimals that formed between Mars and Jupiter were influenced by orbital resonances with Jupiter. Orbital Resonance occurs when two objects periodically line up with each other. In the asteroid belt, orbital resonance occurs when an asteroid has an orbital period that is a simple fraction of Jupiter's orbital period. In these case, asteroids are constantly being tugged by Jupiter which sends it out of its orbit.
Comets
They are important because many of them remain much as they were when they first formed, some 4.5billion years ago.
Pluto and Charon
They are much like comets, big balls of ice and rock. Pluto is very cold Pluto and Charon rotate synchronously, you can only see Charon from one side of Pluto. A day in Pluto is the same length as a month in Charon
Lens
They bend light to form an image. For example the eye's lens bend the light to form an image on the retina.
Global Winds:
They blow in distinctive patterns - Equatorial: E to W - Mid latitudes: W to E - High latitudes: E to W Two factors explain this pattern: 1. atmospheric heating 2. planetary rotation.
Where do comets come from?
They come from the Oort cloud and the Kuiper Belt. Oort Cloud: Spherical cloud of comets. Comets from the Oort cloud usually do not orbit the Sun in the same direction as planets and their orbits are not always elliptical. Kuiper Belt: Comets from the Kuiper belt orbit the Sun in the same direction as planets and have elliptical orbits.
Moon and Mercury
They have so little atmosphere that they could be considered airless. No wind or weather. Their gas densities are far too low for sunlight to be scattered or absorbed. The lack of scattering means that, even in broad daylight, you would see a pitch-black sky surrounding the bright Sun. The lack of absorption means that their atmospheres do not have a troposphere, stratosphere, or thermosphere. In essence, the Moon and Mercury have only extremely low-density exospheres, without any other atmospheric layers. The only ongoing source of gas on the Moon and Mercury is the surface ejection that occurs when micrometeorites, solar wind particles, or high-energy solar photons knock free surface atoms and molecules. This gas never accumulates because it is lost as quickly as it is gained.
How did comets end up so far in the Solar system?
They survived gravitational encounters within the region of jovian planets and did not escape outside the solar system when they collided with larger objects. The Oort cloud consists of leftover planetesimals that were flung outward after forming between the jovian planets The Kuiper belt consists of leftover planetesimals that formed and still remain in the outskirts of the planetary realm.
Venus
Thickest atmosphere out of terrestrial planets. High Pressures There is too much Carbon Dioxide that even planetary probes can't survive with such harsh and hot conditions.
Mars
Thin Atmosphere but thick enough to fly
How do we learn about history of life?
Through Fossils
Why is Saturn's satellite Titan able to retain an atmosphere?
Titan has a large enough mass and is cold enough.
What is the name of a group of asteroids that orbit in two clouds ahead and behind a planet?
Trojan
The pressure of sunlight was one of the forces that cleared the solar nebula.
True
How do the jovian planets affect impact rates and life on Earth?
Ultimately, every asteroid or comet that has impacted Earth since the end of the heavy bombardment was in some sense sent our way by the influence of Jupiter or one of the other jovian planets.
Formula that relates wavelength, speed and frequency
Wavelength x Frequency = Speed
Waves
Waves carry energy outward but do not carry matter along. (Pond Example). - A particle is a thing while a wave is a pattern revealed by its interaction with particles.
Earth has Angular Momentum
We say this because of both its rotation angular momentum and orbital angular momentum
Erosion
Weather driven processes that break down or transport rock. - Ice: Glaciers of ice carved the Yosemite Valley - Water: Canyons (Colorado river did the Grand Canyon) -Wind: Wind wears away and erodes rocks into dust and sand creating Sand Dunes Erosional Debris can create new features.
Kepler's second law implies that:
a planet should move at its slowest speed when it is furthest from the Sun, and it should move at a faster speed when it is closer to the Sun.
Could Life Have Migrated to Earth?
an alternative possibility is that life arose somewhere else first—perhaps on Venus or Mars—and then migrated to Earth on meteorites.
Force
anything that can cause a change in momentum F= mass x acceleration In other terms force equals rate of change in momentum We conclude that the standard unit of force, called the newton, is equivalent to a kilogram-meter per second squared.
radiative energy
energy carried by light
Downward Velocity on Earth
falling objects on earth accelerate on such a way that their downward velocity increases by about 10 meters per second per second.
Weight
force that your mass exerts as a result of gravity . or other forces acting on you. For example you would weight less in the moon due to a weaker gravity Weight=mass×acceleration of gravity
Jovian Moons
formed by accretion within the disks of gas surrounding individual jovian planets That explains why: -their orbits are almost circular -lie close to the equatorial plane of their parent planet -these moons orbit in the same direction in which their planet rotates. They always keep the same face turned toward their planet, just as our Moon always shows the same face to Earth.
If both, the MASS of a satellite orbiting Earth and the radius of its orbit would DECREASE by factor of 2 then gravitational pull from Earth on that satellite would...
increase by a factor of 2
Planets acceleration
planets are always accelerating as they orbit the Sun, because their direction of travel constantly changes as they go around their orbits. We can therefore conclude that some force must be causing this acceleration. As we'll discuss shortly, Isaac Newton identified this force as gravity.
The Age of the Solar System
planets began to form through accretion just over 4.5 billion years ago, a fact we learned by determining the age of the oldest rocks in the solar system
Primary colors of vision
red, blue and green
Spectrum
red, orange, yellow, green, blue, and violet. We see white when these colors are mixed in roughly equal proportions.
James Webb Space Telescope
successor the Hubble Space Telescope; it is planned to study the evolution of galaxies, the production of elements by stars, and the process of star and planet formation.
Atomic mass number
sum of protons and neutrons
Universal Law of Gravitation
tells us the strength of the gravitational attraction between the two objects
What is wavelength?
the distance from one peak to the next one. Peak and trough. (Up and Down)
What star would APPEAR the brightest to an observer on Earth?
the lowest AU
How do we explain "exceptions to the rules"?
the nebular theory suggests that most of them arose from collisions or close gravitational encounters.
Drake Equation
the number of civilizations in our galaxy with which communication might be possible # of civilizations capable of communicating= (# of habitable planets) (fraction of these worlds that actually have life) (fraction of world that have had civilizations) (fraction of worlds that actually have a civilization now)
Habitable zone
the range of distances from the Sun at which a planet like Earth could have oceans and surface life.
Half life (the time it takes for half of a parent's nuclei to decay)
the time it takes for half of the atoms of a radioactive element to decay time= 0 . 100% of parent isotope still remains time= 1 half life . 1/2 of parent isotope remains time= 2 half life . 1/4 of parent isotope remains time= 3 half life . 1/8 of parent isotope remains
Microwaves
the waves between the infrared and radio waves. Micrometers to centimeters.
Hubble Telescope:
used to observe infrared and ultraviolet light in addition to visible light
Fossil evidence suggests that life on Earth arose
very soon after the end of the heavy bombardment.
Seismic Waves
vibrations that travel both through the interior and along the surface after an earthquake - Seismic Waves can tell us about the internal structure of plantes
The light that our eyes can see, found near the middle of the spectrum. Wavelengths ranging from about 400 nano meters at the blue or violet end of the rainbow to about 700 nano meters at the red end.
visible light: Blue to Red