Astronomy Test 4
Which is evidence for the answer to the above question?
-Neptune's rings are trapped among the orbits of small moons. -Neptune's moons show evidence of having been impacted.
What are most craters in the solar system are caused by?
impacts from space
What must be true for a large portion of Earth's core in order for convection to occur?
it must be liquid
Rocks from the lunar crust are
low-density and igneous.
Mercury's core is probably which of the following?
metallic because Mercury is small and of high density.
Where are craters are found?
most solid surfaces in the solar system
Io
most volcanically active object in the solar system -surface features change significantly in just weeks -very smooth surface constantly filling in the cracks
What were the canals on Mars eventually found to be?
optical illusions
What produced iron in Earth's core
some nuclear fusion in a massive star's core, mostly supernovae
Which is not a stage of planetary development?
subduction
What produced the gold and silver in Earth's crust?
supernovae
Basin craters with concentric raised ridges resulted from ____
the crater floor rebounding like waves in water
How can planets with no liquid water have a flooding stage?
the flooding is also by lava
What sites on the lunar surface were considered of the most scientific interest?
the highlands because they held more important geological features
What evidence can you give that Venus once had more water than it does now?
the relatively large abundance of deuterium in the atmosphere Water came from: It came from volcanic degassing. Where did it go? It was broken up by ultraviolet radiation from the Sun.
Differential Rotation
the rotation of a star or planet at different speeds at its equator and poles -Gas Giants don't need to rotate as a solid body, so rotation period varies by latitude
What produced the helium now present in the Sun's atmosphere
It was among the gases from which it formed
What does it mean when a planet is "oblate?"
Its equatorial diameter is larger than its polar axis and it bulges around the equator.
What is not true about global warming?
It is another word for the greenhouse effect True: -The source of the extra carbon dioxide is industrial pollution. -It is caused by increased amounts of carbon dioxide in the atmosphere. -Predictions about how much global warming could occur are unclear.
Which is not true about the greenhouse effect?
It is bad for the environment True: -It is the absorption of infrared radiation by atmospheric molecules. -Carbon dioxide is not the only greenhouse gas. -It is the natural heating mechanism of Earth's atmosphere.
Which of the following is true for Earth's core?
It is solid on the inside, and liquid on the outside. Evidence: shear waves cannot travel through Earth's center
What are seasons like on Uranus?
They are much more extreme than Earth's, and longer.
For which planet is the temperature of its atmosphere coldest at 100 km from the surface?
Uranus
Why is belt-zone circulation difficult to detect on Uranus, compared to Jupiter and Saturn?
Uranus is so cold
For which planet does the temperature of its atmosphere consistently rise as the altitude decreases?
Venus
Why is Jupiter more oblate than Earth?
because its outer layers are not solid and it rotates quickly
What is true about ozone?
-It is a gas in the stratosphere. -It absorbs ultraviolet radiation from the sun. -It is a pollutant produced by automobile emissions.
Ganymede
2 surfaces: older more cratered dark regions and younger, lighter regions -evidence of older tectonic structures and large liquid/slushy ocean beneath a thick crust of ice
The size of a crater is about _____.
20-50 times the diameter of the rock that made it
How can planetary scientists estimate the ages of the outflow channels and valley networks on Mars?
By examining nearby cratered surfaces
Which location experiences earthquakes caused by shifts along a tectonic plate?
California
The mantles of Uranus and Neptune are believed to be which of the following?
They are liquid
How do you know that Earth is differentiated?
Earth has a dense core. Earth has a low-density crust.
Why is Earth's atmosphere different?
Earth has liquid water, which dissolved much of its initial carbon dioxide and converted it to sediments like limestone.
Why is Earth's moon much more spherical than Phobos and Deimos?
Earth's moon is massive enough to gravitationally pull itself into a spherical shape.
Which location experiences earthquakes caused by volcanism?
Hawaii
How do the interiors of Jupiter and Saturn differ?
Jupiter is denser than Saturn and Saturn has less liquid metallic hydrogen in its interior *Jupiters magnetic field is stronger than Saturns
Which is the current prevalent hypothesis for the origin of the Moon?
The Large-Impact Hypothesis
Methane is seen in the atmospheres of Saturn and Uranus, but not in the planets closer to the Sun. What could explain this?
The planets closer to the Sun are too warm to retain it.
Why doesn't Mars have folded mountain ranges like the ones on Earth?
The tectonic processes that formed mountains on Earth did not occur on Mars.
Rank the planets Earth, Venus, and Mars in the following orders. (a) decreasing size (b) increasing mass (c) decreasing number of moons
(a) greatest (Earth) -> (Venus) -> (Mars) least (b) least (Mars) -> (Venus) -> (Earth) greatest (c) greatest (Mars) -> (Earth) -> (Venus) least
Rank the planet Earth, Venus, and Mars in the following order. (a) increasing distance from the sun (b) decreasing surface temperature (c) increasing atmospheric pressure
(a) least (Venus) -> (Earth) -> (Mars) greatest (b) greatest (Venus) -> (Earth) -> (Mars) least (c) least (Mars) -> (Earth) -> (Venus) greatest
What must be true about Earth's core to generate Earth's magnetic field?
-The material must be conductive. -The core must be rotating. -The material must convecting.
Solid particles sticking together is called which of the following?
Accreation
Which is not true about the smooth plains on Mercury?
They appear to have formed just before the Caloris impact.
What is the Kuiper belt?
a population of small rocky/icy objects mostly beyond the orbit of Neptune
What is suggested by rocks collected from the lunar crust?
that the Moon formed in a molten state in which differentiation occurred
Terrestrial plants
the inner four planets (Mercury, Venus, Earth, Mars) -no rings -densities like rock or metal -small, dense, rocky worlds with little or no atmosphere
How can small worlds like Triton and Pluto have atmospheres whereas a larger world such as Ganymede has none?
-Farther from the sun, it is colder and easier to retain gases. -Most of the atmospheric gases sublimate from ice on the surfaces of the objects.
Solar Nebula Hypothesis
-Planetary systems should be common. -According to the theory, planets form from the gases surrounding a star after it forms. -EVIDENCE: Yes; disks of gas and dust and actual planets have been discovered orbiting other stars.
Which is true about the decreasing density of the stratospheric ozone layer?
-There is evidence of an actual hole in the ozone layer -It was caused by chemicals released into the atmosphere by industrial processes. -It could cause public health problems like increased rates of skin cancer.
Which is evidence for the answer to the above question?
-Uranus' rings are trapped among the orbits of small moons. -Uranus' moons show evidence of having been impacted.
How can you determine the relative ages of the Moon's maria and highlands?
-by counting the number of impact craters -more craters = older surface -fewer craters = younger surface -younger surfaces also display short-lived features like rays
What evidence can you give that disks of gas and dust are common around young stars?
-infrared observations of T-Tauri stars -bipolar flows from protostars -visible and radio observations of stars in the Orion nebula
Why do some astronomers think Pluto is a member of the Kuiper belt rather than a planet?
-its location -its size and mass - its composition
Jovian Planets
-large, low density worlds with thick atmospheres and liquid or ice interiors
Which is the process that cleared the solar nebula away and ended planet building?
-radiation pressure and solar wind -sweeping up of debris by planets -ejection of material by close encounters with planets
What evidence can you give that the Solar System formed about 4.6 billion years ago?
-radioactive dating of meteorites -radioactive dating of rocks on Earth, Mars, and the Moon
Which of the following occurred in the Large-Impact Hypothesis?
A large object collided with the young Earth.
Where do the ring particles come from?
As Jupiter's moons are impacted by meteorites, dust particles are ejected that help form the rings.
If you piloted a spacecraft to visit Saturn's moons and wanted to land on a geologically old surface, what moon would you choose? Why?
Choose a moon with a heavily cratered surface, such as Phoebe. Geologically old surfaces are inactive, and old craters are slowly or never resurfaced as geological features stay in place
Particles growing by addition of material an atom or molecule at a time from a surrounding gas is called which of the following?
Condensation
Where did the first Apollo missions land?
In the maria because It had the smoothest landing surface.
Why would you expect Io to suffer more impacts per square kilometer than Callisto?
Io is closer to Jupiter than Callisto, so it is subject to more potentially impacting objects.
What is the relative age of the crater Copernicus?
It is younger than the surrounding maria. proof: bright ejecta blankets and rays
What would you predict for its surface features?
It should be dominated by impact craters with little sign of geological activity.
If Jupiter had a satellite the size of our own Moon orbiting outside the orbit of Callisto, what would you predict for the satellite's density?
It should have a low density, less than 2 g/cm3.
Jupiter vs. Saturn temperatures
Jupiter- warmer Saturn-cooler
Europa
Largely un-cratered surface (young) -water ice -tidal heating -network of cracks resembling ice-flows on earth
Trito
Neptune's largest moon -Thin nitrogen atmosphere -nitrogen geysers -retrograde orbit -gradually spiraling in toward Neptune due to tidal interaction
If Uranus and Neptune had no satellites at all, would you expect them to have rings? Why or why not?
No; ring material comes from the moons.
Why are the belts and zones on Saturn less distinct than those on Jupiter?
Saturn is colder than Jupiter, so belts and zones formed deeper in Saturn's atmosphere where it was hot enough to form. The belts and zones are veiled by a layer of methane crystals in Saturn's upper atmosphere.
What evidence shows that Venus has been resurfaced within the past half-billion years?
Since the cratering rate between Venus, the Earth, and the Moon are about the same, and since Venus has fewer craters than the Moon, Venus must have eroded or covered many of its older craters. The cratering record suggests this happened in the past 500 million years.
Why doesn't Earth have large volcanoes like those on Mars?
Tectonics carries mountains away from volcanic hot spots before they can grow too big.
Which of the following is true about Uranus's magnetic field?
The axes for the magnetic field and its rotation are in different directions.
Why are few craters seen on Europa?
The icy crust of Europa shifts atop an underlying ocean of water, which erases craters from the surface.
How does the large-impact hypothesis explain the Moon's lack of iron?
The iron core of the impacting object could have fallen into the larger body.
Why might the surface brightness of ring particles and small moons orbiting Uranus and Neptune depend on whether those planets have extensive, strong magnetic fields?
The magnetic fields create weak radiation belts which can break methane ices down to release carbon and darken the ices.
How do canals differ from the outflow channels and valley networks on Mars?
The outflow channels and valley networks really exist, while the canals do not.
Why doesn't the material in Earth's core vaporize?
The tremendous pressure from the weight of Earth's outer layers keeps the outer core liquid and the inner core solid.
Why are no craters seen on Io?
The volcanoes and geologically active mountains on Io erase craters from the surface.
Considering the phase of the cores of Uranus and Neptune, how can they have magnetic fields?
Their magnetic fields are believed to be generated by convection in the liquid mantle.
Why are there so many cratered surfaces in the solar system?
There was much debris left over from the formation of the planets and moons, and many collisions in the early solar system.
What evidence would you expect to find on the Moon if it had been subjected to plate tectonics?
There would be volcanoes and mountains. -We don't find that information
Describe the locations of the solstices in the Uranian sky.
They are close to the celestial poles
What is the origin of the rings of Neptune?
They are made of debris from impacts on Neptune's moons.
What is the origin of the rings of Uranus?
They are made of debris from impacts on Uranus' moons.
Which is not true about the intercrater plains on Mercury?
They are older than heavily cratered surfaces
The cores of Uranus and Neptune are believed to be which of the following?
They are solid.
What is the major flaw in the Co-Accretion and Fission hypotheses?
They do not explain the different compositions of the Earth and Moon.
Why are Mars' moons, Phobos and Deimos, nonspherical?
They do not have enough mass to gravitationally pull themselves into a spherical shape.
Describe the locations of the equinoxes in the Uranian sky.
They lie along the celstial equator
Would you expect the other Jovian planets to be more oblate than Earth as well?
Yes. None of them are solid and they all rotate quickly
How many impact craters does Earth have?
about 150 but many more have been erased by erosion
What produced the helium now present in Jupiter's atmosphere?
captured directly from the solar nebulae
Which of these conducting materials is not found in the Earth's core?
copper
Which is the first stage of planetary development?
differentiation
Callisto
farthest Galilean moon from Jupiter -likely frozen solid -no evidence of tectonic features -Valhalla: large impact crater
Which kind of planet has rings?
jovian planet because there are more massive
Charon
largest moon of Pluto. Both are made of rock, and ice Evidence: densities
Titan
largest moon of Saturn -Covered by a thick atmosphere of mostly nitrogen and methane
What produced the helium present in the Sun's core?
nuclear fusion
In what ways is Earth unique among the Terrestrial worlds?
oceans, a nitrogen-oxygen atmosphere, life
Where is Uranus's magnetic field centered?
offset from the center of the planet
The central peak in complex craters is the result of _____.
overshooting rebound
Mercury's core is probably which of the following?
partially molten because it has a weak magnetic field
Most of the composition of Pluto and Charon is which of the following?
rock
Which is something that Venus and Earth have in common?
size, mass, surface gravity
Which is something about Venus and Earth that is different?
surface temperature, atmospheric pressure and composition
Which planets are more dense?
terrestrial planets Based on the nebula theory: the reason is because- -Terrestrial planets formed from solid material that condensed out of the solar nebula close to the sun, where it was too hot for them to capture gases -Jovian planets started out with solid material as well, and were far enough from the sun for a layer of ice to form, after which they became massive enough to capture slower-moving gases.
What evidence is there that Pluto and Charon are made of rock and ice?
their densities