Astronomy exam 4
In 2013, a small stony asteroid collided with the Earth above the Russian city of Chelyabinsk. What was the result?
A fireball briefly brighter than the Sun could be seen in the sky
The largest continental (highland) area on Venus is called
Aphrodite
What is one way that astronomers have actually gotten an idea of the age of the surfaces of terrestrial planets other than the Earth?
Counting craters
Which of the following spacecraft is NOT leaving the solar system?
Galileo
The largest satellite (moon) in the solar system is
Ganymede
In radioactive dating, the measure scientists use to note how long (on average) a particular radioactive nucleus will take to decay is called its
Half-life
Which of the jovian planets has the shortest period of rotation (the shortest day)
Jupiter
Which of the following statements about the seasons on Jupiter is correct?
Jupiters axis is hardly tilted so it has no real seasonal variations
Why is it so much easier to determine the length of the day on Mars than on Venus?
Mars' atmosphere is generally pretty clear (so the surface is visible) while Venus is always cloudy
The planet closest to the Sun in the solar system is
Mercury
The lakes found in the north polar region of Titan are filled with liquid
Methane
Which element plays the same role on Titan as water does on Earth (existing as gas, liquid, and solid)?
Methane
In the far future, a daring interplanetary tourist wants to go "hang-gliding" on the jovian planet with the highest equatorial wind speeds. Which planet would have the fastest wind at its equator?
Neptune
Today, the chemistry of the terrestrial planets does not include a lot of free hydrogen. Chemists call the chemistry in places like the Earth:
Oxidized
The first trans-Neptunian object astronomers found (in 1930) is called
Pluto
Which planet has the biggest moon relative to its own size? Not the biggest moon in terms of kilometers, but the biggest as a percentage of the size of the planet it orbits
Pluto
The comet that broke into more than 20 pieces and then collided with Jupiter in 1994 was
Shoemaker-Levy 9
The process by which Venus became so much hotter than the Earth is called
The runaway greenhouse effect
In the far future, a visiting tourist from another planetary system asks to see the most massive object in our solar system. Where would you take him/her/it?
The sun
The satellite which has the thickest atmosphere (so thick that it's quite a surprise for a satellite) is
Titan
Which of the following is NOT a way that Jupiter differs from terrestrial planets?
its surface has many more craters from early collisions
The fact that some asteroids cluster in what are called asteroid families is probably the result Of
collisions which broke up larger bodies into a number of smaller ones
The smaller objects in the solar system composed mainly of ices (frozen gases) that usually orbit far from the Sun are called:
comets
A very rich and eccentric tourist in the future hires you to fly him to a region of Venus' atmosphere where the temperatures and pressures are the most Earth-like. Where would you take him?
in the cloud layers about 50 km above the surface
Valles Marineris is a wide, deep network of chasms stretching for some 2500 miles on the surface of Mars. How do we believe such a big set of canyons formed originally?
it was caused by tectonic pressures from deep within the planet
The inner planets are made mostly of rock and metal because
it was so hot where the inner planets formed that the lighter materials evaporated
To obtain the wonderful images of the jovian planets in our textbook (out where the sunlight is a lot fainter) what did the Voyager spacecraft cameras have to do as they flew by each world?
swivel the cameras backwards to keep pointing in the same direction as the craft flew by
Halley's Comet was given that name because Edmond Halley was Question options:
the scientist who pointed out that the orbit of the comet was such that it should return every 76 years or so
Which of the following characteristics do all four terrestrial planets have in common?
they all have solid surfaces with signs of geological activity on them
What makes the rings of Neptune different from those of other planets we know?
they are clumpy (or bulging) in places
Mars rovers (such as Opportunity and Curiosity) have identified evidence that their landing sites were once under water. Which of the following is among the kinds of evidence they have identified?
they found rock formations that show the area was under water and also minerals that only form in water
Which of the following statements about the geysers on the moon Triton is true?
they involve plumes of nitrogen on the sunlit side of Triton
The spacecraft that visited Pluto and send back our first images
more than one of the above
Which of the following is evidence for volcanic activity on Venus?
All of the above (the fact that the lava plains are only 500 million or so years old, the existence of large volcanic mountains such as Sif Mons, the discovery of thousands of small volcanic cones of the surface of Venus,the pancake domes of Venus)
The first spacecraft to orbit another planet circled Mars in 1971. It was
Mariner 9
What do the magnetic fields of Jupiter, Uranus, and Neptune have in common?
all three have their magnetic axes offset from the center of the planet
Radioactive dating techniques have revealed that our Earth and Moon are approximately how old?
About 4.5 billion years
A baseball pitcher wants to impress his girl-friend with how strong his throwing arm is. On which of the following bodies would the pitcher be MOST likely to be able to throw a baseball (a fast ball) so fast it would actually go into orbit?
Asteroid Ida
The largest and most massive of Saturn's rings is the
B ring
On some parts of Mars, it gets cold enough for a gas to freeze out of the atmosphere that does not freeze out by itself at the temperatures and pressures on Earth. This gas makes up some of the polar caps on Mars and is
Carbon dioxide
The first asteroid to be discovered (which is also the largest one) is called
Ceres
Pluto's big satellite is called
Charon
Pluto was discovered through the patient searching of
Clyde Tombaugh
Different asteroids reflect different percentages of the light falling on them. This is due to the fact that they have different
Compositions
The scientist who first proposed that comet nuclei were "dirty snowballs" was:
Fred Whipple
The primary clouds in the atmospheres of Jupiter and Saturn are composed of
Frozen ammonia crystals
By far the most abundant element in the giant (jovian) planets is
Hydrogen
If you were to take a large sample of the four giant planets, the most common element you would find in them is:
Hydrogen
The first asteroid confirmed to have a satellite (moon) was
Ida
Why are there no smaller craters on the surface of Venus, only bigger ones?
In Venus' thick atmosphere all smaller chunks of material burn up before they can reach the surface
The spacecraft that sent back the most detailed radar images of Venus and showed us features as small as a football field is:
Magellan
The observation that began the 19th and early 20th century fascination with Mars as a place for life was
Schiaparelli's seeing what seemed to him to be long straight features on the red planet
One of the most impressive features of the geology of Mars is an uplifted area about the size of North America, with volcanoes on it, which is called the
Tharsis Bulge
In 2012, NASA's Spaceguard Survey concluded that astronomers had now identified 90% of the asteroids with diameters greater than 1 km. How could astronomers know that they had reached this goal?
The people doing the survey began to find the same objects over again, indicating they were reaching the limits of their survey
What do astronomers think is the origin of the many irregular moons around the outer planets (irregular meaning they are orbiting backwards and/or have eccentric orbits)?
These moons were likely formed elsewhere and captured by the giant planets
How have astronomers learned what different asteroids are made of? Question options:
They examine the spectrum of the sunlight that reflects from the asteroid
The planet that orbits "on its side" (i.e. has its rotation axis perpendicular to the plane of its orbit) is
Uranus
The spacecraft that soft-landed successfully on the surface of Venus (and briefly sent back pictures while sitting in that destructive environment) were called
Venera
Much of what we have learned about the jovian planets and their satellites has come from the work of two spacecraft called
Voyager
Which of the following statements about the tails of comets is FALSE?
a comet always has a nice long tail, even when it is far from the Sun
Astronomers believe that Jupiter's strong magnetic field is caused by
a huge layer of metallic hydrogen inside Jupiter
The rings of the outer planets consist of
billions of chunks (of various sizes) that all orbit the equator of each planet
How were the rings of Uranus discovered?
by using the Kuiper Airborne Observatory (the telescope aboard an airplane) to observe Uranus moving in front of a distant star
More than 75% of the known asteroids:
can be found in a belt between Mars and Jupiter
Which of the following statements about the atmosphere of Mars today is FALSE?
droplets of liquid water rain irrigate the surface of Mars regularly
Astronomers believe that Mars formed with a much thicker atmosphere than it has today. Where did this atmosphere go?
it escaped into space (and some later froze out as Mars got cold)
Which of the following statements about Charon is FALSE?
it has a significant atmosphere
Which of the following statements about the planet Venus is true?
it has a thick layer of clouds containing sulfuric acid droplets
Which of the following statements about the unusual object Chiron is FALSE?
it is one of the largest asteroids, just a little smaller than Vesta
If our estimates of the number of comets in every part of the solar system are correct, the total mass contained in comets must be:
on the order of the mass of all the planets put t
What allowed the Voyager 2 spacecraft to make a "tour" of all four of the jovian planets in the late 1970's and the 1980's?
the four planets were approximately aligned on one side of the Sun and we used the gravity of each planet to speed up the spacecraft to get to the next one in its path
What is the cause of its many volcanic/geyser-like eruptions on the moon Io?
the gravitational stress of being so close to Jupiter and its other large moons heats the Io's inside
Comets change as they approach the Sun in their orbits. Which of the following statements about a comet approaching the Sun is FALSE?
the gravity of the comet nucleus holds on to the evaporated material, and it all eventually freezes back into the nucleus
What evidence can you give that shows the surface of Jupiter's moon Europa must be relatively young?
we see very few craters compared to the surfaces of Callisto and Ganymede
Mars appears to have long branching channels that have the appearance of being formed by a flowing liquid. Yet we know that liquids would not stay liquid in the very thin atmosphere we have on the Martian surface? So how can we explain the channels?
Mars had a thicker atmosphere long ago when the channels formed
During the process of differentiation,
Heavier materials sink to the centers of molten planets
Which of the following is NOT a terrestrial planet?
Jupiter
The mountains on Pluto are made of frozen water, which at Pluto temperatures, is as hard as rock. Pluto also has a smooth, round basin which could be thought of as a frozen sea. What material is in the basin (nicknamed Sputnik) likely to be made of?
Nitrogen
The planet that most resembles the Earth in size and internal composition is
Venus
What planet can come closest to the Earth in its orbit and look brightest in our skies?
Venus
Which of the following is NOT a correct statement about the rotation of Venus?
Venus rotates in roughly the same time period as Earth
When astronomers say that Ganymede is a differentiated body, they mean that it
has a heavier core, surrounded by a lighter, icy mantle and crust
Which of the following characteristics distinguishes Uranus from every other planet in our solar system?
it rotates on an axis tilted almost 90 degrees to the circle of its orbit
In general, the further planets are from the Sun, the cooler they are. What other factor can have a significant influence on a planet's surface temperature?
its atmosphere (whether it has one and how thick it is)
What was a surprise to astronomers when they carefully examined Neptune with the Hubble Space Telescope in 1994?
the Great Dark Spot had disappeared
Which of the following places is most likely NOT to be differentiated?
A small asteroid
The Red Spot of Jupiter is
All of the above: Variable in size, made of reddish colored material, a high pressure storm system in the atmosphere, long-lived (observed since the 1600's)
The Galileo spacecraft measured that the moon Ganymede had a magnetic field, indicating that its interior was at least partly melted and warm. What do scientists think is the most likely reason for this?
Ganymede is heated by tidal forces from Jupiter
The Shoemaker-NEAR spacecraft explored two asteroids, Mathilde and Eros. A big difference between them is that:
Mathilde appears to be pile of 'rubble' (a collection of separate rocks) while Eros is solid
The jovian planet that has the longest year (period of revolution) is
Neptune
The canals that late 19th and early 20th observers thought they saw on Mars turned out to be
Optical illusions
Two small moons in the solar system, known since the 19th century, turn out to be captured asteroids. These two moons are
Phobos and Deimos around Mars
The material that would eventually make all the major bodies in our solar system first gathered together as smaller pieces which astronomers call
Planetesimals
One of the key reasons that professional astronomers (as opposed to the public) are interested in comets is that they
are icy pieces left over from the time that our solar system formed that can give us clues about that early time
Generally, planets and moons in our solar system are named after
gods and goddesses from mythology
The rate at which a collection of the same radioactive atoms will decay depends on:
only on internal processes within the atoms; nothing external matters
The large reservoir of comet nuclei far beyond Pluto, from which we believe new long-period comets come into the inner solar system, is called:
the Oort Cloud
Which of the following would NOT be one of the problems faced by an unprotected Earthling stranded on Mars? (Unprotected meaning no space suit.)
the extreme (high) heat at most latitudes
At the moment when the Voyager spacecraft got closest to Uranus, the Sun was shining directly on the planet's south pole. Uranus takes about 17 hours to rotate once on its axis. If Voyager took a photo of the south pole 8.5 hours later, what would it observe?
the south pole was brightly lit, with the Sun shining down on it
How does Saturn's F ring stay so thin (narrow), when the other rings are so wide?
there are 2 shepherding satellites on either side of it
