Astro Exam 2
Piece of rock or metal that survives entry into the Earth's atmosphere and lands on the ground
meteorite
How often does the Earth enter the asteroid belt?
never
How would we get Mercury to be reclassified as a minor body?
remove mass so it's irregularly-shaped
What event cleared out the gas from the protoplanetary disk?
the Sun became a star and its solar wind blew away the gas
Why does this article say Saturn's rings are disappearing?
the Sun is giving the ice particles a charge, and then they react to Saturn's magnetic field
Roughly how old is our solar system?
4.5 Billion years
Halley's Comet has the formal name of 1P/Halley. Which meteor shower is debris from Halley's Comet?
Eta Aquariid in May
True or false: the Moon is the only object that raises a tide on Earth
False
What force drove the collapse of the nebula, the first step of the process that would eventually form our solar system?
Gravity
There are two moons in orbit around two planets; the orbits are both the same size. The moon orbiting planet Indigo takes 2 hours to orbit once. The moon orbiting planet Saffron takes 2 days to orbit once. Which planet has more mass?
Indigo
In class we learned why Jupiter's rings are dark and why Saturn's are bright, but there is still the question of why Jupiter's rings have so little material and Saturn's rings have more. Simulations investigated the difference and have a possible explanation. What do astronomers suggest is the reason why Saturn have big rings and Jupiter has skinny little rings?
Jupiter's large innermost moons (the Galilean moons) scattered any potential ring material, while Saturn doesn't have large moons close to the planet like that
You should be careful when reading webpages about tides, especially explanations of the high tide on the opposite side of the Earth from the Moon. Please look at these two explanations, Moonconnection and BrainStuff, and decide which got the explanation right.
Moonconnection didn't explain the far side high tide correctly and BrainStuff did
The Earth experiences two tidal bulges: a large one raised by the Moon and a weaker one raised by the Sun. As the Moon orbits the Earth, the arrangement of these two tidal bulges will vary. This recording (MOV) shows the tides the Earth experiences. Watch the animation and observe the range of water height for high and low tide for Spring and Neap tides. When the orientation of the Moon is just right, the high tides from the lunar bulge and the solar bulge line up, causing a very strong "Spring tide" --- an especially high high tide and a very low low tide. At what Moon phase(s) will you see a Spring tide?
New Full
Which of the following statements correctly describes the motion of the particles in rings?
Particles in the inner rings orbit the planet at a faster speed than particles in the outer rings
These are the orbit sizes of two of Jupiter's moons: Io orbit semi-major axis 0.002819 AU (1.87 Jupiter's diameter) Europa orbit semi-major axis 0.004473 AU (2.98 Jupiter's diameter) Io's orbital period is _________ than Europa's and calculating Jupiter's mass using Io's orbit would give you _________ mass of Jupiter compared to using Europa's orbit
Shorter, the same
We would need advanced warning to change the motion of an asteroid headed toward Earth. What is the minimum time we would need with our current technology?
a few years
The presence of nickel-60 in meteorites suggests that the gravitational collapse of the solar nebula (the cloud that would eventually form our solar system) might have been triggered by?
a shockwave from a nearby supernova
How could I make the tides on Earth stronger (high tides higher and low tides lower)? Consider both the lunar and solar tides.
add more mass to the Moon move the Moon closer to Earth move Earth closer to the Sun
Say your friend tells you about a star with 5 terrestrial planets orbiting in the opposite direction of its 3 jovian planets. This discovery would be inconsistent with how we expect stars and planets to form since?
all the planets formed in a disk-shaped nebula that was rotating in the same direction
The nebular hypothesis predicts that protosolar nebula became disk-shaped as it collapsed. While all of these statements about our solar system are true, which observation supports this idea?
all the planets orbit the Sun in the same direction and in nearly the same plane
I am made of rock and have a moon orbiting me but never a tail
asteroid
I orbit between Mars and Jupiter and am mainly made of rock
asteroid
I orbit right alongside Ceres --- we "rock out" our orbit together because I'm made of rock!
asteroid
Rock or metal objects orbiting the Sun with semi-major axes between Mars' and Jupiter's
asteroid
same composition as terrestrial planets but so low mass it usually has a odd potato shape
asteroid
With a semi-major axis of 2.8AU, where does dwarf planet Ceres live?
asteroid belt
Which is true about minor body orbits?
asteroids have smaller orbits but comets get closer to the Sun
We see dramatic evidence of heating on various moons, including volcanoes on Io, a sub-surface ocean on Europa, and geysers on Enceladus. What is responsible for heating these moons?
changing tidal forces
Earth runs into dust and rocks from my tail and experiences meteor showers
comet
I am a fragile fluffy ball of ice and dust
comet
I spend most of my time in the outer edges of the solar system, although I do swing around the Sun very quickly for a tiny part of my orbit
comet
Icy and dusty objects orbiting the Sun with semi-major axes ranging from just larger than Neptune's to the edge of our solar system
comet
My orbit is huge, very eccentric, and can be inclined almost any direction to the plane of the solar system
comet
Sunlight heats my ice, making it sublimate into a gas
comet
gets very close to the Sun in its orbit, making its ice turn to gas and stream out into space
comet
The slow-moving stream of light from molecules and dust
comet, space
The debris region between Mars and Jupiter and the region just outside of Neptune's orbit are both called "belts", but the debris region that reaches to the outer edges of the solar system is called a "cloud". Why the difference in name?
debris in the belts have orbits close to the plane of the solar system, just like a belt stays around your waist
small moon-sized spherical objects that orbit the Sun, mostly located beyond Neptune
dwarf planet
small, spherical, mostly made of rock and ice (water, carbon dioxide, methane, ammonia)
dwarf planet
Jovian planets grew larger and faster than terrestrials because Jovians formed _____, where there were solid particles of ice, rock, and metal --- rather than just rock & metal
farther from the proto-Sun than the frost line
What force caused the planets to move (migrate) and change each other's orbits?
gravity from planets interacting with each other
Why do moons orbit instead of flying away from their host planet?
gravity ties them to the planet
What is the Roche limit?
how close a moon can get to a planet before being ripped apart by gravity
Which of these can exist as solid flakes outside both the soot line and the frost line (beyond 3.5 AU)?
hydrogen & helium "ices" (water, ammonia, nitrogen) rocks & metal
Halley's comet has a semi-major axis in the Kuiper belt. Why isn't it considered a dwarf planet like Pluto and the others?
it is irregularly-shaped
doesn't have a surface, just atmosphere and clouds that get thicker as you go deeper into the planet
jovian planet
the largest kind of planet orbiting the Sun
jovian planet
The Late Heavy Bombardment was a time when the rate of impacts dramatically increased, and astronomers suspect it was caused by the?
jovian planets' migrating, specifically the ice giants hitting the Kuiper belt
How would we get Saturn's moon Titan to be reclassified as a dwarf planet?
make it orbit the Sun in a debris region like the asteroid belt
According to University of Virginia researchers, what is the source of Saturn's newly discovered tilted ring system?
material from one of its moons
Bright streak of light in the sky as air is heated by debris falling from space
meteor
bright light as a piece of debris enters the Earth's atmosphere and heats up the air in front of it
meteor
We see "shooting stars" and comets in the sky, so fill in the blanks to tell me why we see light from them. A _____ glows because the air is hot, while a ____ is bright because it is reflecting sunlight
meteor trail comet tail
A quick streak of light from hot glowing gas as something burns up as they fall to Earth is a ______; the streak of light is in _____ and it can be 25 km long
meteor, Earth's atmosphere
Rock (usually) leftover from a comet tail that is in space but about to enter the Earth's atmosphere
meteoroid
What are planetary rings made of?
millions of little particles each orbiting the planet
Tautatis is a small, irregularly shaped object in the asteroid belt that orbits the Sun. This is an animation showing Tautatis rotating. What would we classify it as?
minor body
Amalthea is a small, irregularly-shaped object that orbits Jupiter. This animation shows Amalthea rotating. What would we classify it as?
moon/satellite
Why are the larger asteroids more spherical in shape?
more mass means a stronger gravity, which pulls in any pieces that are sticking out too much
In Star Wars the ship had to dodge around closely-packed asteroids in an asteroid belt (like this). Is this realistic?
no, asteroids are small compared to their orbit sizes, so they are very widely-spaced with large distances between them
Why is the Oort cloud important for understanding the formation of the solar system?
objects in the Oort cloud were shifted into those orbits during planet migration
Which observation suggests that planets migrated?
other stars are found to have jovian planets orbiting very close to their star, and the Oort cloud is spherical rather than disk-shaped
The Roche limit for a planet is around 2.5x the planet's radius (or slightly more than the planet's width). Where is Earth's Moon?
outside Earth's Roche limit
Where in the protoplantery disk would objects like jovian plants from?
outside of the frost line
Particles inside a planet's Roche limit don't clump and they stay as a ring system, but particles outside of the Roche limit can clump and form a large moon. Why is this?
outside the Roche limit the tidal force is much less and won't tear apart the moon as it tries to form
Protoplanets that became the terrestrial planets formed ____ the soot line and ____ the frost line
outside, inside
Planetesimals that became the Jovian planets formed ____ the soot line and ____ the frost line
outside, outside
The astronomer who discovered the dwarf planet Eris suggests there might be another object far beyond the Kupier belt. If this Planet X exists, it would be about 10 times the mass of Earth and 2-3 times the size of Earth, putting it in the ice giant category, and have an orbit with a semi-major axis of 700 AU. You can read more about this object on NASA's page. If this object exists, what would we classify it as?
planet
Say you want Earth's Moon to go through phases in two weeks rather than one month. What should you do to make the Moon orbit Earth faster?
push the Moon into a smaller orbit
Which of these methods helps us learn the age of our solar system?
radioactive dating of asteroids and meteorites
has surfaces that can be covered in craters, paved over by volcanoes, eroded by liquid water, or decorated with structures built by funny bipedal animals with electronic gadgets like cell phones
terrestrial planet
lower mass than jovian planets but enough mass to be spherical in shape, mostly made of rock (oxygen, magnesium, silicon) and metal (iron and nickel)
terrestrial planet
Jovian planets absorbed hydrogen and helium from the protoplanetary disk; why didn't the terrestrials do this?
terrestrials were too small and their gravity too weak to hold any hydrogen or helium
The Moon can raise tides on Earth but those tides are small, less than a yard tall. That's not very impressive! Why is the force between the Earth and the water stronger than the force between the Moon and the water?
the Earth has more mass and the water is closer to the center of the Earth than the center of the Moon
Why does the Earth experience meteor showers?
the Earth sometimes runs into debris as it crosses the orbits of comets
After Galileo's observations in 1600s, Jupiter was said to have four moons. As telescope technology improved, we could see fainter and fainter objects. Currently, we say Jupiter has more than 60 moons. The number of moons of Jupiter is shown over time in the following graph. The number of known moons increased over the past few hundred years. What is the most reasonable explanation for this?
the actual number probably stayed the same, but our telescopes got better so we could see previously undetectable moons
A comet and an asteroid approach Jupiter's Roche limit. Which can get closer before tidal forces rip it apart?
the asteroid
Astronomers discovered an asteroid with rings in the same manner as they discovered Uranus had rings. how did they do it?
the asteroid passed in front of a star, and astronomers saw the rings block the star's light
How do comet tails behave as the comet orbits the Sun?
the comet only has tails when it is close to the Sun, and the dust tail stays in the orbit and the ion tail always points away from the Sun
Why don't we see large moons very close to the planets (like inside the Roche limit)?
the difference in gravity between the side near the planet and far from the planet would rip apart a large moon
If the solar nebula was all made of the same material, why did the protoplanetary disk have solid "ice" particles (flakes of water, ammonia, nitrogen) only found far from the proto-Sun?
the inner regions were too hot and the "ices" evaporated and became gas
When Earth was forming it was hit by another small planet, and some material splashed into space from that impact ended up going the right speed to orbit Earth as rings. That material eventually clumped together to become our Moon. Why didn't this material stay as rings? Hint: consider the size of the Moon's orbit.
the material was outside Earth's Roche Limit, so it wouldn't stay as ring particles
Astronomers think they've observed an exoplanet with a ring system larger than Saturn's. how do astronomers know the rings of J1407b are there?
the rings blocked the light of the star as the planet was crossing in front of the star, just like how we discovered the rings of Uranus
if you look at the Frequency Asked Questions section on Blackboard, you'll see the last question is "Why is it so hard to study things in our solar system (like the possible Planet 9) compared to studying galaxies that are much farther away?" So, why is it difficult to study these distant objects?
they appear as a little point of light because they are too far away to resolve as a detailed disk (like Mars) they move very slowly across the sky because they have large orbits they are very faint because they far from the Sun and don't reflect much sunlight they move very slowly across the sky because they are moving slowly in their orbits
Saturn's rings are spectacular, but the other jovian planets' rings are very hard to see. Why are Jupiter's, Uranus', and Neptune's rings so dark?
they are made of dark particles and there just aren't many particles in the rings
What stops the ring particles from clumping together to make a moon?
they are too close to the planet and the tidal force from its gravity is too strong
What happened to the molecules of the "ices" (water, methane, ammonia) present inside the frost line?
they existed as a gas
Where did the heavier atoms present in solar nebula (nitrogen, oxygen, iron, silicon) come from?
they were created in stars that existed before the Sun, who polluted the gas around them
A tidal force could arise on a moon because one side is farther from the planet and feels a ____ force of gravity than the near side
weaker
With a semi-major axis of 39AU, where does dwarf planet Pluto live?
Kuiper belt
Which planets have rings?
Neptune Uranus Jupiter Saturn
