astronomy ch 6-11

What is meant by average density of a planet? What does the average tell us?

Differentiates terrestrial and Jovian planets The average density tells us something about its composition

Explain why mercury does not have a substantial atmosphere

Mercury doesn't have a substantial atmosphere because it's too small and hot. Since its small it doesn't have a lot of gravity so gas escapes easily. And with extreme hot tempts, gas molecules move quickly and escape mercury's gravitational fields

Describe the kinds of features that can be seen on the moon with a small telescope

With a small telescope we can see what is on the side of the moon facing towards us, which is mostly Maria (dark regions on the moon formed from lava flows), craters, and terrae (light colored highlands)

interior heat

energy from formation, radio activity

outer core

molten

3 energy sources

solar, tidal and interior

radiation

warm object emits photons that carries energy heat goes into atmosphere

what is the evidence that other stars existed before our sun was formed?

Chemical elements are not formed in our sun, but in other stars, are present in the sun and the planets

What is diffraction? Why does it limit angular resolution of a telescope? What is another important phenomenon that is a restriction to angular resolution?

Diffraction is an intrinsic property of light waves and using a larger lens telescopes ability to see fine details - wavelength of light/ diameter of telescope mirror = resolution Atmosphere is the second restriction cause it causes the light to bounce around

heat transfer through 3 layers

conduction, convection, and radiation

Why do geologists suspect that Pangaea was the most recent in a succession of supercontinents?

fits like a puzzle and matching fossils across seas where they may have previously connected

athenosphere

fluid plastic

convection

fluid, moves and carries heat athenosphere layer- fluid/flexibe/flows, convection can move around hot rock goes up, cool rock goes down

lithosphere

hard rigid crust

conduction

heat traveling b/w 2 objects in contact lithosphere layer- top of mantle solid - goes up

chemical differentiation

heavy elements sank below and lighter ones float to the top

plate tectonics

lithosphere plates float on top of athenosphere athenosphere has convective motion that pushes lithosphere plates around earth

uplift

2 continental plates crash into each other creates mountains

divergent plate boundary

2 plates moving apart causing a gap in the middle (rifting) forms canyons and seas

Describe 2 reasons why astronauts need to wear space suits on the moon

2 reasons they need to wear space suits are, space suits provide oxygen for them to breathe and control body temperature it prevents them from getting burnt by ultraviolet radiation (moon has no ozone layer)

What is a 3 to 2 spin orbit coupling? How is this rotation period of an object exhibiting 3 to 2 spin orbit coupling related to its orbital period? What aspects of mercury's orbit cause it to exhibit 3 to 2 spin orbit coupling? What telescope observations proved this?

3 to 2 spin orbit-coupling means that every 1 rotation equals 2/3rd orbit This means its orbital period will be 2/3rd it's rotation period Happens because mercury is lopsided due to tidal forces and eccentric Radio telescopes (radar) can measure its rate of rotation

What is a plastic material? Which parts of Earth's interior are described as being plastic?

A plastic material is one that is able to flow. The asthenosphere is plastic because the temperature is slightly greater than the melting point.

what is meant by a substance's condensation temperature? What's its role in the formation of planets?

A substances condensation temperature is the temperature at which a substance solidifies from gas form. If a substance has high concentration tempt like rocks, then it can become part of the inner solar system planets. If it has a low condensation tempt then it becomes part of the outer solar system planets

what is meant by accretion? Why are the terrestrial planets denser at their centers than their surfaces?

Accretion is when planets become larger by the accumulation of material. Through the process of chemical differentiation, the centers are more dense because the solid elements like iron sunk down to the center when high tempt was on it and less silicon rich elements floated up

What is an asteroid? What is a trans-Neptunian object? In what ways are these minor members of the Solar System like or unlike the planets?

An asteroid is a small, rocky body orbiting around the Sun. A TNO is a small, planet-like body orbiting around the Sun. They are both like planets in that they orbit the Sun but they are unlike planets in that they are small, very numerous

What is convection? What causes convection in Earth's atmosphere?

As air rises, it transfers heat to its surroundings. The rising air cools and becomes denser. It then sinks downward to be heated again, and the process starts over. This motion is called convection. The heat that drives convection in the Earth's atmosphere comes primarily from the Sun.

why did terrestrial planets form close to the sun and Jovian planets away from the sun?

Because Jovian planets elements can only form far away from the sun where its cold so helium and hydrogen wouldn't be evaporated and can be incorporated into the planet and terrestrial planets can only form near the sun where the tempt is high

Why does the sky look black on the moon even during the daytime?

Because it has no atmosphere and thus light can not be scattered

If the earth and moon are essentially the same age, why is there such a disparity in the ages of rocks on the 2 worlds?

Because on earth erosion and tectonic plates changes the earths surface. Plate tectonics change old crust into new crust, while on the moon the rocks stay old because they've basically stayed unchanged for years.

why are terrestrial planets smaller than Jovian planets?

Because the elements that form terrestrial are too rare to make them the planet any bigger, while Jovian planets which are made of mostly abundant elements like helium and hydrogen have plenty material to make the planet larger

if hydrogen and helium account for 98% mass of all the atoms in the universe, why aren't earth and the moon mainly these 2 gases?

Because these gases are too light to be retained by earth's gravity

Why was it necessary to send unmanned spacecraft to land on the moon before sending humans there?

Because they knew the surface of the earth was super refined from the impacts hitting its surface (Regolith, which is like flour) and they wants to make sure our spacecraft wouldn't sink into the moons surface Also it was less expensive- takes a lot of money to keep people in space for years

Describe how energy is transferred from Earth's surface to the atmosphere by both convection and radiation.

Energy is transferred from the surface to the atmosphere by convection as air heated by contact with the surface rises and by radiation as the warm surface radiates infrared that is absorbed by the greenhouse gases.

What are the characteristics of a terrestrial plane?

Four inner planets- rocky, small, less mass, more dense

What are characteristics of a Jovian planet?

Four outer planets- gaseous, more mass, less dense, large

What is the relationship between the extent to which a planet or satellite is cratered and the amount of geologic activity on that planet or satellite?

Geologic activity on a planet or satellite will erase evidence of cratering.

How does the greenhouse effect influence the temperature of the atmosphere? Which properties of greenhouse gases in the atmosphere cause this effect?

Greenhouse gases, including water vapor and carbon dioxide, are transparent to visible light but not to infrared radiation. Visible sunlight has no trouble entering our atmosphere and warming the surface. Infrared radiation coming from the heated surface is partially trapped by the atmosphere, thus raising the temperatures of both the atmosphere and the surface.

Explain how convection in Earth's interior drives the process of plate tectonics.

Heat is convected upward in the asthenosphere, exerting an upward pressure on the crust. Oceanic rifts allow the magma to flow. This occurs in the oceans because the crust is thinner there.

hat phenomena tended to make the young Earth freeze over? What other phenomena prevented this from happening?

If the Earth's young atmosphere lost its water vapor, the surface would cool due to a decreased greenhouse effect. The young Sun was cooler and this contributed to a cooler surface. A small amount of CO2 in the atmosphere would enhance the greenhouse effect, warm the planet, and keep the surface mostly free of ice.

What is liquid metallic hydrogen? Why is it found only in the interiors of certain planets?

In liquid metallic hydrogen, electrons are free to move from one atom to another. It takes enormous pressure for hydrogen to assume this state.

Why is it impossible for liquid water to exist on the surface of the moon?

It can't exist because it has no atmosphere to control temperature, thus water would boil and evaporate immediately or freeze. Pressure and tempt from the atmosphere impact the existence of liquid water

The deepest wells and mines go down only a few kilometers. What, then, is the evidence that iron is abundant in Earth's core? That Earth's outer core is molten but the inner core is solid?

It is believed that the core contains mostly iron because iron is heavy and very abundant in the universe, and some meteorites are rich in iron. It is believed that the outer core is molten and that the inner core is solid because of the magnetic field, the shadow zone, and the loss of S waves in the interior.

what is the nebular hypothesis? Why is it accepted?

It is that the entire solar system, sun and planets, formed from the solar nebula, a vast, rotating cloud of gas and dust

what is interstellar medium? How does it become enriched overtime with heavy elements?

It's a weak collection of gas and dust that spreads through the spaces between the stars and it becomes enriched with heavy elements over time because as each star dies the heavy material ejected from the star becomes part of the interstellar medium and thus increases its heavy material

Why is surprising that mercury has a global magnetic field? Why does the 58.6 -day rotation period of mercury imply that the planet can only have a weak magnetic field?

It's surprising mercury had a global magnetic field because it has such a slow rotation that usually means a weak magnetic field like the moon. As well as it being so small, its interior should have cooled long ago but its high density- similar to earths- means it has large iron core- meaning its partially molten (material liquefied by heat) still Its rotation period is slow which should mean it has a weak magnetic field

Why is it impossible to see mercury or Venus in the sky at midnight?

Its impossible to see mercury or Venus in the sky at night because since their closer to the sun than earth, you can only see them in the sky right before or after sunrise/ sunset. They never rise far above the horizon, which is why you can only see them during these times.

Describe Earth's magnetosphere. If Earth did not have a magnetic field, do you think aurorae would be more common or less common than they are today?

Magnetosphere= the region of space around a planet in which the motion of charged particles is dominated by the planet's magnetic field . Without the magnetosphere, auroras would be more common and widespread because the solar wind would be striking the Earth constantly, although only on the daylight side.

On the basis of the moon rocks brought back by the astronauts, explain why the Maria are dark colored and the lunar highlands are light colored.

Maria rocks are created from solidified lava and are dark, dense, and contain heavy elements like iron. Lunar highland rocks are old, less dense and contain elements like silicon and calcium. Lunar highland rocks were created when the moon was molten; since they were less dense they floated to the top and mostly cover the moons surface now

Describe the differences between Maria and the lunar highlands. Which kind of terrain covers more of the moons surface? Which kind of terrain was formed later on the moons history? How do we know?

Maria= dark regions of the moon formed when something/ meteoroid hit the moon and made a large basin, that then got filled with lava from the moons mantle and then solidified when the moon cooled and created dark patches Lunar highlands are light color regions of the moon, is on the far side of the moon and has a lot of craters The terrain that covers the moon surface more is the lunar highlands which cover almost 85% of the moons surface The Maria is relatively young and formed later in the moons history. We know this because it doesn't have a lot of craters which were formed by meteoric bombardments thus it hasn't been exposed to it as long as its surrounding terrain

What kinds of features are found on Mercury? How do they compare to surface features on the moon? Why are they probably much older than features on earth?

Mercury is covered with craters, plains and scarps The craters found on mercury are very similar in looks and the way they formed to Maria found on the moon They are much older than those found on earth because since it has no atmosphere, geological activity and is small and hot, there's nothing to erase craters like that on earth. Thus they are much older

Why are typical rocks found on Earth's surface much younger than Earth itself?

Most surface rocks are the result of plate tectonics or intrusive volcanic activity, or they are sedimentary and metamorphic rocks, all the result of relatively recent geologic activity.

Why is the earth geologically active and the moon is not?

NO ATMOSPHERE The earth has an atmosphere that can control temperature, as well as water, erosion and tectonic plates. Earth's continents and sea floor are shaped and changing through seafloor spreading, mountain building and subduction. Because the moon has no atmosphere, it doesn't have erosion and has no tectonic plates to create mountain ranges or volcanoes. Thus the moon surface barely changes.

Describe the differences between near and far sides of the moon. What is thought to be the explanation of these differences?

Near side = mostly Maria, no highlands Far side = almost all craters and lunar highlands Explanation- the earth's gravitational force pulled the moons core towards the earth. Because of this the crust of the near side of the moon thinner and therefore impacts to that side could crack through the mantle and creates Maria's. While the far side of the moon had a thicker crust and thus impacts to that side didn't reach deep enough to crack through the mantle and make lava flow out. Instead it created craters and lunar highlands.

Is magnifying power a good way to evaluate telescopes?

No because there is other factors such as the size of the lens. The bigger the lens the better the telescope cause it can absorb more light and this lets you see dimmer or brighter objects more clearly.

Could you use a magnetic compass to navigate on the moon? Why or why not?

No you could not because the moon has no magnetic field. The moon has a small iron rich core and once showed a weak magnetic field, however as it was cooling its magnetic field disappeared

explain the formation of the solar system by explaining why all the planetary orbits lie on the same plane, are circular and orbit the sun in the same direction

Planetary orbits all lay on the same plane because the rotation of the solar nebula caused the nebula to flatten out and created the proto-planetary disk. They are all circular because of the gravitational pulls from other objects in the solar system. They go in the same direction because the direction all came from the rotation of the first solar nebula

what is a planetesimals? How did they rise to the terrestrial planets?

Planetesimals are created from accretion, it was when rocks collided and made large chucks that stuck together by chemical bonds. They rose to terrestrial planets the same way through accretion. They became proto-planets and then terrestrial planets.

Describe the various ways in which Earth's surface is reshaped over time.

Plate tectonics and erosion are primary causes of changes to the Earth's surface.

In what ways is Pluto similar to a terrestrial planet In what ways is it different?

Pluto's position in the solar system would tend to cause it to be classified as a Jovian planet, but physically Pluto is more like a terrestrial planet Tilted orbit Eccentric orbit Outer solar system but not gaseous Density between inner/outer planets Small

what are proplyds? What do they tell us about plausibility of our model of the solar system origin?

Proplyd is a rotating, flattened disk around the proto-sun which eventually planets are formed from It explains to us why all our planets orbit the same direction of the sun and are all on the same plane

What is the regolith? What causes its powdery character?

Regolith is the result of years of lots of tiny impacts (micrometeorites) on the moons surface that has grounded surface into a fine powder (the regolith)

How are scientists able to measure what the atmospheric CO2 concentration and average surface temperature were in the distant past?

Scientists have determined the CO2 levels by analyzing air bubbles trapped at various depths in the ice that blankets the Antarctic and Greenland. Scientists measure the relative amounts of two oxygen isotopes 16O and 18O. Their ratio is a sensitive measure of the temperature at the time that air was trapped inside the ice.

Disadvantages of retracting telescopes compared to reflecting

Size limit, chromatic aberration, lens has to be flawless/ it's expensive, lens absorbs some of the light- reflecting fixes these problems

Summarize the history of Earth's atmosphere. What role has biological activity played in this evolution?

The Earth's atmosphere outgassed from the interior as the Earth became molten. The gases consisted of hydrogen and helium that were lost to space. There was also water that froze on the surface and carbon dioxide and nitrogen that remained gaseous. The carbon dioxide warmed the surface by the greenhouse effect melting the ice. The carbon dioxide then dissolved in the liquid water and was deposited as carbonate rock. Oxygen was later added by its release during photosynthesis in plants.

What are the Van Allen belts?

The Van Allen belts are two rings of ionized atoms and electrons trapped in the Earth's magnetosphere.

What are the asteroid belt, the Kuiper belt, and the Oort cloud? Where are they located? How do the objects found in these three regions compare?

The asteroid belt between Mars and Jupiter contains numerous small, rocky planetoids. The Kuiper belt, which extends from Neptune's orbit, is thought to be the source of short-period comets, which are icy, "dirty snowballs" composed mostly of silicates and water. The Oort cloud, is also a comet reservoir

If heat flows to Earth's surface from both the Sun and Earth's interior, why do we say that the motions of the atmosphere are powered by the Sun?

The heat flow from the Earth's interior to its surface is minuscule—just 1/6000 as great as the flow of energy we receive from the Sun.

The inner core of Earth is at a higher temperature than the outer core. Why, then, is the inner core solid and the outer core molten instead of the other way around?

The inner core of the Earth is solid in spite of the high temperature due to the high pressure.

Describe the interior structure of Earth.

The interior of the Earth consists of a solid iron inner core surrounded by a liquid iron outer core. Then comes a solid rock mantle whose upper layer, the asthenosphere, is plastic. The uppermost layer is the lithosphere of solid lightweight rocks whose surface is the Earth's crust.

How is the magnetic field of a planet different from that of a bar magnet? Why is a large planet more likely to have a magnetic field than a small planet?

The magnetic field of a planet is due to the motion of electric currents in the core, whereas the magnetic field of a bar magnet is due to the inherent magnetic properties of the atom. The core of a giant planet is compressed, giving rise to larger-scale currents.

Why do geologists think that Earth's magnetic field is produced in the liquid outer core rather than in the mantle?

The mantle rocks are mostly silicates, poor conductors of electricity compared to iron, which forms the liquid outer core of the Earth.

explain why most of the satellites of Jupiter orbit that planet in the same direction Jupiter rotates

The part of the solar nebula that became the Jovian system behaved like the entire solar nebula but in miniature

Why do you suppose that active volcanoes, such as Mount St. Helens in Washington State, are usually located in mountain ranges that border on subduction zones?

The plate being subducted pushes into the magma and forces it out through the volcanoes in order to relieve the pressure.

How does the size of a terrestrial planet influence the amount of cratering on the planet's surface?

The smaller and older the world, the more cratering is visible because there is less internal geologic activity, and hence the craters remain uncovered.

Does global warming increase the surface temparature of all parts of Earth by equal amounts of by different amounts? What consequences does this have?

The temperature increase is predicted to be greater at the poles than at the equator. effects- Dry places become drier Wet places become wetter More, larger storms (hurricanes- powered by warm ocean water) Glaciers, ice caps melt - (no more water supply for irrigation so we can't have agriculture)

The absorption lines in the spectrum of a planet of satellite do not necessarily indicate the composition of the planet or satellite's atmosphere. Why not?

The terrestrial planets are rocky and hence mostly silicates and iron compounds. The Jovian planets are largely hydrogen and helium.

What is light pollution? What are its effects and how can we minimize it?

Too much light or bad weather can make it difficult to see light in the sky. Like trying to see stars in the city. To minimize this we build telescopes at higher elevations, places with dry climate, dark locations - away from cities, and near oceans so we can reduce light disturbance.

During Apollo 14 mission, astronaut hit 2 golf balls over the moon. Give 2 reasons why they traveled much further than golf balls do on earth.

There is no air resistance on the moon to slow them down and weaker gravity takes longer to pull the balls back to the ground.

the graphite in our pencil is a form of carbon. Where were these carbon atoms formed?

These carbon atoms were formed by stars that have either been gradually expelling the heavy material like atom into the universe through nebulosity or through supernovas. Their heavy material gradually increases the interstellar medium and allows us to have materials like carbon in earth- and us and in pencils.

Why are radio telescopes large? Why is a single radio telescope having poorer angular resolution than a large optical telescope? How can resolution be improved?

They are large because they use large reflecting dishes to focus radio waves onto a detector. Larger provide sharp images and if you link smaller dishes together it improves angular resolution.

Why do most scientists favor the collisional ejection theory of the moons formation?

They favor the collision ejection theory because its similar to how inner planets were formed- small objects collided and accreted together to form the inner planets. The collision ejection theory is similar- the proto-earth was struck off center by a proto-planet, mars- sized, and ejected debris that formed the moon. It's also explained by the moons low density and small inner core.

How do we know that the surface of Venus is older than Earth's surface but younger than the Moon's surface?

Venus has only smaller craters. Larger ones comparable with the Moon's craters have been erased by geologic activity.

Ozone and carbon dioxide and each make up only a fraction of a percent of our atmosphere. Why, then, should we be concerned about small increases or decreases in the atmospheric abundance of these gases?

We worry about the carbon dioxide and ozone even though they are minor components of our atmosphere because they have profound effects. Carbon dioxide is a greenhouse gas and increases in its concentration can cause the global surface temperature to rise to the point where the environment is drastically altered. If the small amount of ozone was depleted, the ultraviolet radiation from the Sun would rise to lethal levels at the surface.

Do all planets orbit the sun in the same direction? And are they all circular?

Yes they all orbit in the same direction No, mercury isn't circular

Describe the process of plate tectonics. Give specific examples of geographic features created by plate tectonics.

o Lithosphere plates float on asthenosphere o Asthenosphere has convective motion o This motion pushes lithosphere plates around Plate tectonics is the movement of large portions of the crust. The movement is caused by magma squeezing out along the mid-oceanic ridges pushing the plates apart in a process called seafloor spreading. Some geographical features created by plate tectonics include mountain ranges, submarine trenches, island arcs such as Hawaii, and volcanoes.

subduction

ocean plate gets pushed under continental plate (cause continental is larger) melts rock= creates magma and pushes up towards the surface and creates volcanoes

2 plates on earth

ocean plates- thin/dense continental- thicker/ lighter

slip fault

only causes earthquakes plates grind next to each other

convergent plate boundary

plates crash into each other

atmospheric pressure

pressure of air molecules due to atmosphere above you at higher evaluations the atmosphere is thinner and less dense

Combing light from 2 or more optical telescopes improves angular resolution. Why?

reduces diffraction limit small wavelength and big telescope = better resolution

How are satellites similar to terrestrial planets? How are they different? Which are largest?

similar to the terrestrial planets in size and in having a definite surface of solid material. They have lower densities 7 large moons = moon (earth), Io, Europa, Ganymede, Callista- Jupiter, Titan (Saturn) and Triton (Neptune)

inner core

solid

Carbon cycle

•Volcanoes emit CO2, dissolves rain to the ground •Water/CO2 ends up in the ocean, settling to ocean floor ricks •Ocean floor subducts carbon back into mantle •Then outgassed again (cycle begins again)