Astronomy Test 2

What is a dwarf planet?

"Small bodies" that are large enough to be round.

Which currently observed features and patterns in the Solar System need to be addressed by acceptable model for solar system formation?

1) Why are there two major types of planets? 2) What caused the orderly patterns of motion in our solar system? Direction of orbit & rotation. 3) Orbits are roughly circular. 4) They all lay on the same plane.

Apply the concept of escape speed to explain the differing atmospheres of 4 terrestrial planets.

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What is a meteor/meteorite?

A flash of light produced as a small object enters the atmosphere.

Identify the planets in our solar system which have rings and describe the hypotheses as to the origins of these rings

All four Jovian planets have ring systems. These planets all have ring systems between they formed from dust created in impacts on small moons orbiting those planets. We know this because the particles that form the rings are too small to have survived from when the planets were formed.

Compare the orbital characteristics of Pluto with those of the planets.

All of the planets have more circular ellipses than Pluto does. Plutos orbit is not clear, there are other things in its pathway.

What is an astroid? What is the Astroid Belt?

An astroid is a chunk of ice or rock which is not big enough to crush itself into a sphere. It has a "potato" shape. Asteroid Belt orbits between Mars and Jupiter. It is material left over from the formation of the solar system. They were prevented from turning into a planet from the tides from Jupiter.

What is a moon?

Any large object that orbits a planet.

What is a star?

Balls of plasma that produce energy by nuclear fusion.

Why is Pluto not classified as a planet since 2006?

Because its orbit is full of other objects, not a clear pathway.

Relate the distribution and chemical composition of asteroids and comets to the nebular theory of solar system formation.

Comets form outside the frost line. Asteroids form inside the frost line.

What is a solar system?

Consists of a star orbited by planets, moons, and lots of debris (comets, asteroids, dust)

What are the components of Earths interior?

Core: highest density Mantle: moderate density Crust: lowest density

Describe the various geological features found on the surface of Mars.

Craters - Many early craters have been erased. Amount of cratering differs across the surface. Volcanism - Mostly large shield volcanoes. Largest volcano in the solar system Tectonics - canyons form proving tectonics. Erosion - dust devil tracks & sand dunes due to wind erosion.

Describe the general features of the surface of Venus. Explain what the study of crater on Venus tells us about the age of its surface.

Craters - has craters but less than Moon, Mercury, or Mars. Geological processes have erased some craters. Volcanism - Has lots of volcanoes, both shield volcanoes and stratovolcanoes. Tectonics - fractured and contorted surface indicates tectonic stresses. Plate tectonics seem to have shut off long ago, so it has no carbon cycle to regulate its temperature. Erosion - not much erosion shown.

Compare tectonic activity and volcanoes on Venus with those on Earth

Earth has plate tectonics and volcanoes are only where the plates meet. Venus plates have been shut off a long time ago and volcanoes are all over the surface.

What is our current modal for the formation of the Moon?

Giant impact - A Mars-sized planetesimal crashes into the young Earth, shattering both the planetesimal and our planet.

Describe the most likely process that lead to existence of objects which are "exceptions to the rule" of observed patterns such as unusual axis tilts of some planets, unusually large moons, or moons with unusual orbits.

Heavy Bombardment - leftover planetesimals bombarded other objects in the late stages of solar system formation Origin of Earth's Water - water may have come to Earth by way of icy planetesimals. Captured Moons - Unusual moons of some planets may be captured planetesimals. Odd Rotation - Giant impacts may explain the different rotation axes of some planets (Uranus)

What is a comet?

Icy, outer-solar system remnants.

Relate the patterns of chemical composition and the existence of the two main types of planets to its formation mechanism?

Inside the frost line, it is too hot for hydrogen compounds to form ice. Only heavy materials (metals and rocks) within the frost line could condense. Outside the frost line, it is cold enough for ice to form. Heavy and light materials (water and ice) outside the frost line.

Describe the major distinguishing surface characteristics of four Galilean moons (Io, Europa, Ganymede and Callisto).

Io - most volcanically active body in the solar system, these eruptions continue to change Io's surface. Europa - tidal stress cracks on surface ice. Ganymede - two different terrains, one heavily cratered and the other has few craters. largest moon in the solar system Callisto - "classic" cratered ice ball, very little geological activity, has a magnetic field.

Explain the origin of magnetic field on Jupiter.

It has metallic hydrogen inside, which circulates and makes a magnetic field.

Explain why it is difficult to learn about Venus from Earth=based observations alone.

It is so hot on the surface that the only space ship that visited the planet only lasted 50 minutes on the surface.

Compare and contrast jovian planets with terrestrial ones in terms of chemical composition, size, location, formation mechanism, rings, number of moons, etc.

Jupiter & Saturn = H & He Uranus & Neptune = H compounds. Terrestrial planets made of rock and molten. Only Jovian planets have rings. Jovian planets outside the frost line, Terrestrial planets inside the frost line, Jovian planets have many more moons than Terrestrial planets do.

What are the trans-neptunian objects: Kuiper's Belt & Oort's Cloud?

Kuiper Belt - a ring of comets and icy objects orbiting just beyond Neptune. This is debit left over from the formation of the solar system. Oort Cloud - a spherical cloud of perhaps a trillion comets surrounding the solar system.

What are the surface features, composition, masses, atmospheres, and interiors of Venus?

Lots of volcanoes. Has some impact craters but not many. Very thin atmosphere. Run away green house effect so very hot. No plate tectonics on Venus.

Differentiate between the major surface features of the Moon. Describe the origins of lunar highlands and maria

Lunar Maria - smooth, dark less heavily cratered than lunar highlands. Made by floods of runny lava. Formed from large impact weakens the crust & lava builds up then cools. Lunar Highlands - Old, heavily cratered lunar highlands that make up 83% of the Moon's surface.

Compare and contrast Earth and Mars in terms of their sizes, composition, atmospheres, and geological histories

Mars has an atmosphere which is more than 100x thinner than Earths. Very cold temperatures and pressure compared to Earth. There is never a cloud in the sky but loads of dust and high winds. Mars is smaller than Earth.

Mercury vs. Moon - Compare surface features, composition, masses, and origins.

Mercury and Moon both have been heavily cratered, and both have tectonics. Both experienced or formed from large impact. Both look very similar and about the same size.

What are the surface features, composition, masses, atmospheres, and interiors of Mercury?

Mercury has a metallic core about the size of our Moon.

Describe the topography and features of Mercury's surface and their origins.

Mercury interior is dominated by metallic core about the size of our Moon. Got metallic interior possibility from a giant impact. Mixture of heavily cratered and smooth regions. Smooth regions are likely ancient lava flows. Long cliffs indicate that Mercury shrank early in its history

What is the nebular theory for the formation of the solar system? How does it help support the existence of comets and asteroids?

Molecular cloud fragments begin to collapse. As it collapses, it heats up. It also speeds up due to conservation of angular momentum. Particles in the cloud collide, changing their random motions. They change their random motion into an orderly, spinning disk of dust and gas orbiting a protostar. Asteroids and comets were leftovers from the accretion process. Rocky asteroids inside the front line, icy comets outside the frost line.

Explain how composition of lunar rocks and Moon's density provide evidence for the giant impact theory for Moon formation

Moon's average density is smaller than Earths, but the same as the density of Earth's mantle. The lunar rocks on the Moon are similar to Earth's mantle material.

Explain how impact cratering reveals geological age of planetary surface.

Most craters happened soon after the solar system formed. A surface with many craters has not changed much in 3 billion years.

Describe the origin of Earth's magnetic field. Explain the relationship between planet's size and rotation rate, and the existence of magnetic field

Motions of charged participles are what create magnetic field. A planet needs a molten interior, convection, and moderately rapid rotation in order to have a magnetic field.

Describe the atmospheric composition of the giant planets, cloud formation, and atmospheric structure.

Multiple cloud layers determine the colors of Jovian planets. All have strong storms and winds.

Describe the approximate interior structures of each of the jovian planets.

No solid surface layers under high pressure and temperature get crushed the more layers that are added and the stronger the pressure. Cores made of hydrogen compounds, metal, and rocks. The layers are different for each planet though.

Note some distinguishing characteristics of Pluto's large moon Charon

On the moon Charon, there are smooth regions that resemble the lunar Maria, suggesting the eruption of "lava" which is this case might be water.

How does distance from the Sun impact geological activity?

Planets close to the Sun are too hot for rain, snow, ice and so have less erosion. 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 more erosion.

How does planets rotation impact geological activity?

Planets with slower rotation have less weather, less erosion, and a weak magnetic field. Planets with faster rotation have more weather, more erosion, and a stronger magnetic field.

Describe information about Pluto's surface deduced from the New Horizons images

Pluto haze haze layers in its atmosphere. There are a diversity of terrain on Pluto. Pictures of its surface shows evidence of ongoing geological activity.

What are the origins of Primary & Secondary atmospheres?

Primary - match the composition of the Sun, and are mostly hydrogen and helium. All planets in the solar system started out with primary atmospheres. Today, only the Jovian planets have this type of atmosphere. Secondary - formed through outgassing from volcanoes, and the evaporation and sublimation of rocks, ices or oceans. Today, only terrestrial planets have this type of atmosphere.

Explain why jovian moons are more geologically active than small rocky planets.

Rocks melt at higher temperatures, and only large rocky planets have enough heat for activity. Ice melts at lower temperatures. Tidal heating can melt internal ice, driving activity.

What is a planet?

Rocky, icy, or gassy, and they produce much energy

How does planetary size impact geological activity?

Smaller worlds cool off faster & harden earlier. Larger worlds remain warm inside, promoting volcanism and tectonics.

Compare and contrast Venus and Earth in terms of their sizes, masses, surface features, and composition of atmosphere. Explain why the surface of Venus is inhospitable to human life.

Surface of Venus is very hot and inhospitable to human life because of the runaway green house effect. Earth and Venus are nearly the same size, probably have retained the same level of internal heat, and have similar densities and compositions.

Terrestrial vs. Jovian planets?

Terrestrial (Earth-like) - small, rocky, think or atmosphere, few moons Jovian (Jupiter-like) - large, liquid + gas, small rocky core, many moons.

Use the carbon cycle concept to explain how Earth regulated its climate and counteracts small temperature variations. Describe the main factor that has potential to disturb this delicate balance and its relation to the greenhouse effect.

The carbon cycle regulates Earth's carbon dioxide levels at a non-greenhouse level. When the Industrial Age came, humans pumped dangerous amounts of carbon dioxide into the atmosphere. Oxygen and life are critical for preserving the Earth's atmosphere. Without life constantly providing oxygen, Earth's atmosphere would be similar to that of Venus or Mars.

Relate the observed patterns of motion of objects in the solar system to its formation mechanism?

The formation mechanism has the molecular cloud fragments spinning all in the same direction. When planets began to form, they were all rotating and orbiting in the same direction.

Explain the origins of the gaps in the rings of Saturn.

The gaps in the rings are where small moons are orbiting the planet.

Explain why there is a relationship between planet radius and level of geological activity. Apply the concept of surface area-to-volume ratio.

The total amount of heat contained in the planet depends on its volume Loss of heat through radiation happens from its surface. Larger objects have a smaller ratio and cool more slowly. Smaller objects have a larger ratio and cool off faster, and harden easier.

Describe the evidence for the presence of water currently on Mars' surface. Explain why we do not find water in a liquid state presently on Mars.

There is no atmosphere, and no pressure, which makes water turn into ice or vapor.

Describe what we learned from the landing on Titan with the Huygens probe

This probe discovered there is liquid methane, "rocks" of ice on Titan.

Explain the concept of tidal heating and give examples of places where it is significant. Explain how tidal forces generate the geological activity on some of Galilean moons.

Tidal heading is when an object gets squished and stretched when orbiting another larger object. When close the object it is orbiting, large tidal bulge. When far from object, small tile bulge. Ex. found on most of Galilean moons. By squishing and stretching the objects, they heat up internally creating geological activity.

Explain several pieces of evidence which demonstrate that there was liquid water on Mars

Trench dug by space lander took pictures 4 martian days apart. Showed that ice evaporated. Dry riverbeds on Mars, runoff and outflow channels, erosion from water on craters. The martian rocks are round which can only be done from water erosion. Gypsum found on surface, needs H2O to form.

Why do Venus and Earths temperatures differ, despite their similarities?

Venus has a runaway green house effect. Its atmosphere is very efficient at trapping infrared light which has raised its temperature.

Compare and contrast atmospheres of Venus, Earth and Mars in terms of their chemical composition, temperatures, average surface, and pressure.

Venus: - mostly carbon dioxide - very hot (873 F) - high pressure (92 atm) Earth: - mostly nitrogen, some oxygen - normal temp (63 F) - normal pressure (1 atm) Mars: - mostly carbon dioxide - low temperatures (-63 F) - low pressure (0.006 atm)

Describe the variability of Mars' atmosphere.

Very thin atmosphere, clouds of ice and dust sweep across it regularly. As the winter progresses, the atmosphere cools. The carbon dioxide and oxygen in the atmosphere condense into the caps, dropping to pressure. With the atmosphere being thinner, it can heat more easily.

What are the surface features, composition, masses, atmospheres, and interiors of Mars?

Very thin atmosphere. Cratering depends on what part of Mars you are looking at. Large shield volcanoes, and largest volcano in solar system.

Describe the processes which shape planetary surfaces

Volcanism -eruption of molten rock onto surface Tectonics - disruption of a plant's surface by internal stressed Erosion - surface changes made by wind, water, or ice. Impact cratering - impacts by asteroids or comets.

Compare the volcanoes and canyons on the Mars with those on Earth

Volcanoes on Mars are mostly shield volcanoes. The largest volcano in the solar system lays on Mars. The canyons on Mars and much larger than the Grand Canyon on Earth. Mars has volcanoes and crayons, like Earth, but they are MUCH bigger on Mars.

How does radioactive dating help us determine the age of the solar system?

When an element decays from radioactivity, it turns into another element. The half-life is the time for half of the nucleus in a substance to decay. We use this information to identify the age.

Describe the mechanisms by which planets produce and lose heat; explain which methods dominate the energy balance of each planet.

When planets were young, accretion & differentiation occurred. Radioactive decay is most important heat source today. Planets lose heat through convection, conduction, and radiation.

What are the stages of the carbon cycle?

atmosphere → water/plants (photosynthesis) → back to atmosphere (from water)/plant goes to animal → animals and plants decompose → fossil fuels → combustion back to atmosphere

What is the greenhouse effect?

the trapping of the sun's warmth in a planet's lower atmosphere due to the greater transparency of the atmosphere to visible radiation from the sun than to infrared radiation emitted from the planet's surface.