ASTR 1110 Chapter 13

The first asteroid to be discovered (which is also the largest one) is called Ceres Eros Gaspra Davida

Ceres

When the Dawn spacecraft explored the largest asteroid Ceres, it discovered white spots that appear to be salt and volcanic mountains made of water ice. This led astronomers to which of the following ideas: Ceres formed from the breakup of a much larger body. Ceres may have (or may have had) a liquid ocean under its crust. all asteroids are made of frozen water. Ceres is really one of the terrestrial planets that got kicked out of its former orbit.

Ceres may have (or may have had) a liquid ocean under its crust.

The Galileo spacecraft passed by which two asteroids and sent back close-up images and data? Ida and Gaspra Vesta and Ceres Chiron and Pholus Eros and Toutatis

Ida and Gaspra

According to our textbook what is the best way to defend ourselves against an asteroid which is on course to collide with the Earth in 7 years? The only thing we could do would be to move some people to the Moon so they could survive. If we do it early enough we could explode something on or near the asteroid to deflect it slightly so that years later it would then miss the Earth. Asteroids are all rubble piles so the only thing that would protect us would be a huge thermo-nuclear explosion that vaporizes the entire asteroid. There is no problem because all asteroids burn up by friction in the Earth's thick atmosphere. There is no possible protection for us. If an asteroid is headed our way we are all doomed.

If we do it early enough we could explode something on or near the asteroid to deflect it slightly so that years later it would then miss the Earth.

In 1994 a comet was observed to break into more than 20 pieces and collide which which giant planet? Neptune Saturn Uranus Jupiter

Jupiter

Why do astronomers today think that we have an asteroid belt and not a planet between Mars and Jupiter? Io's volcanoes produced asteroids. the Sun's wind stops blowing there. Jupiter's gravity prevented material in that zone from getting together. a planet exploded and broke apart.

Jupiter's gravity prevented material in that zone from getting together.

In the far future, an entrepeneur with a large fleet of space ships decides to capture and bring to Earth some valuable asteroids. If at that time there is a shortage of usable metals on Earth what type of asteroids should his employees search for? C-type M-type S-type None of the above. primitive

M-type

Which of the following statements about Near-Earth Objects is TRUE? we have identified just about all NEO's with diameters greater than 1 km. it is unlikely that any NEO's have hit the Earth during our planet's history. NEO's can include both asteroids and comets that cross the Earth's orbit. no NEO has passed closer to the Earth than the orbit of the Moon.

NEO's can include both asteroids and comets that cross the Earth's orbit.

Two small moons in the solar system have been found to be captured asteroids. These two moons are: the Earth's moon and Venus's moon Dione and Titan around Saturn Io and Europa around Jupiter Phobos and Deimos around Mars

Phobos and Deimos around Mars

Which of the following is not an accomplishment of the Rosetta mission to Comet Churyumov-Gerasimenko (C-G)? Rosetta took close-up images of Comet C-G and sent them back to Earth. Rosetta dropped the Philae lander on Comet C-G. Rosetta took samples of the surface material of Comet C-G and sent them back to Earth. Rosetta matched orbits with Comet C-G and flew alongside.

Rosetta took samples of the surface material of Comet C-G and sent them back to Earth.

Which of the following statements about the tails of comets is FALSE? the Earth can pass through the tail of a comet without suffering harm. the tail of a comet can sometimes be ahead of the comet in its orbit. a comet always have a nice long tail even when it is far from the Sun. some comets have both a gas tail and a dust tail. a gas tail always points away from the Sun.

a comet always have a nice long tail even when it is far from the Sun.

If there are at least a million asteroids how did spacecraft like Galileo survive their trip through the asteroid belt? NASA sends its spacecraft above and below the orbits of the asteroids in the belt to avoid collisions. spacecraft use a magnetic repulsion tool to make sure asteroids do not come too close. the known asteroids are typically less than a centimeter across so they do not represent a danger to spacecraft. although there are many asteroids they are widely spaced (there is a lot of space between them).

although there are many asteroids they are widely spaced (there is a lot of space between them).

One of the key reasons that astronomers are interested in comets is that they are pieces splintered off one of the giant planets so they can provide us with sample of their composition. are beautiful to look at. are all visitors from other start systems which can tell us about what conditions are like in the distant reaches of the Milky Way Galaxy. are icy pieces left over from the time that our solar system formed that can give us clues about that early time.

are icy pieces left over from the time that our solar system formed that can give us clues about that early time.

Why were asteroids not discovered until the 19th century? several asteroids collided with each other in early 1801 calling the attention of astronomers. in their long looping orbits it was not until the 19th century that an asteroid came close enough to the Earth to be detectable. asteroids are generally small compared to planets and require a good telescope and patient searching to spot them. although asteroids are the same size as the planets they are completely covered with dark dusty material which means they reflect almost no light.

asteroids are generally small compared to planets and require a good telescope and patient searching to spot them.

More than 75% of the known asteroids: can be found in a belt between Mars and Jupiter. lie farther out from the Sun than the orbit of Saturn. cross the Earth's orbit at least once as they revolve around the Sun. are made of icy material that is highly reflective. were once part of a planet as large as Jupiter.

can be found in a belt between Mars and Jupiter.

The fact that some asteroids cluster in what are called asteroid families is probably the result of: resonances with the jovian planets. comets which pass through the asteroid belt and attract asteroids to them. strong magnetic fields found in some asteroids. collisions which broke up larger bodies into a number of smaller ones.

collisions which broke up larger bodies into a number of smaller ones.

Short period comets like Comet Halley come back again and again at predictable intervals. return to the Oort Cloud during each of their orbits. can never be observed without a telescope. have a long tail visible during their entire orbit around the Sun.

come back again and again at predictable intervals.

A main difference between asteroids and comets is that asteroids are mostly made of rock and comets are mostly made of carbon compounds metals ice vapor (gas)

ice

Astronomers estimate that there may be a trillion comet nuclei orbiting beyond Pluto. Why then do we not see more comets in our skies? most comets are so small that millions pass by the Earth completely undetected. most comets have orbits that only bring them inward as far as the orbit of Jupiter. most comets collide with Jupiter each year and are thus not seen. most comets remain in stable orbits beyond Pluto only a few have their orbits disturbed and come into the inner solar system.

most comets remain in stable orbits beyond Pluto only a few have their orbits disturbed and come into the inner solar system.

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 together about the mass of Ceres about the mass of the Earth about the mass of the Moon

on the order of the mass of all the planets put together

One reason we know more about the surface composition of the asteroid Vesta than about most other members of the asteroid belt is that Vesta's orbit crosses the Earth's orbit roughly once a century. pieces of Vesta have landed on Earth as meteorites. Vesta's surface is made of water ice and is extremely reflective. Vesta's volcanoes still spew out a lot of material that goes into orbit around Vesta.

pieces of Vesta have landed on Earth as meteorites.

The large reservoir of comet nuclei far beyond Pluto from which we now believe new long-period comets come into the inner solar system is called the Kohoutek Cloud the Oort Cloud the Lowell reservoir the Alvarez belt

the Oort Cloud

According to astronomical tradition who gets to suggest the name for a newly discovered asteroid? a special committee in Italy where the first asteroid was discovered the discoverer of the asteroid a special committee of the U.N. set up for this purpose the president of the country of the discoverer

the discoverer of the asteroid

Which part of a comet is the DENSEST? the nucleus the atmosphere the gas tail the dust tail

the nucleus

When larger fragments of Comet Shoemaker-Levy 9 crashed into Jupiter in 1994 they changed the motion of Jupiter making its orbit larger. they produced vast plumes of material that changed the color of Jupiter's inner moons. they exploded in Jupiter's atmosphere releasing energy equal to millions of megatons of TNT. they reassured scientists on Earth that this kind of comet impact could NEVER happen to Earth.

they exploded in Jupiter's atmosphere releasing energy equal to millions of megatons of TNT.

Comets get significantly brighter in our skies as they approach the Sun because they get closer to the Earth than when they were outside the orbit of Mars. they get bigger as the ice evaporates. they reflect more sunlight as they get closer to the source of light. they move faster and faster.

they get bigger as the ice evaporates.