Astronomy Ch.14 - Solar System Debris
Large meteoroids are thought to collide with Earth
a few times in every million-year period.
The body which wiped out the dinosaurs was about
as big as one of Mars' moons.
Before it arrived in orbit about Eros, the NEAR spacecraft also flew past
asteroid Mathilde.
Asteroid 2004 FH passed within a tenth of the Earth-Moon distance in March 2004. When its period was found to be about nine months, it was classified as a(n)
aten asteroid.
Which of the following gives direct information about the age of the solar system?
meteorites from asteroidal debris
Pluto's density is most similar to
moons of the jovian planets.
What part of a comet has only been seen by a space probe?
nucleus
The Kuiper Belt objects have orbits that
stay out just beyond Neptune and close to the ecliptic.
The Trojan asteroids have orbits that
stay sixty degrees ahead of or behind Jupiter.
Iron meteorites are believed to come from
the core of a dense M-type asteroid, now broken up.
Carbonaceous Chondrites are believed to come from
the crust of a differentiated C type asteroid, now broken up.
Meteor shower debris is believed to come from
the disintegration of a short period comet over many returns to the Sun.
What are Dactyl, Gaspra, Mathilde, Eros, and Ida?
the only four asteroids explored by spacecraft to date
The Oort Cloud is thought to be
the spherical cloud of comets and some larger icy bodies surrounding the outer solar system.
Meteorites are valuable to astronomers because
they may provide evidence about the process in which the solar system was born.
About what percent of all asteroids are C-type asteroids?
10%
About what percent of all asteroids are S-type asteroids?
15%
Pluto was discovered in
1930.
Pluto's bulk density is:
2,100 kg/m3, similar to Callisto's mix of rock and ice.
Halley's Comet last passed Earth in 1986. It will be due back in
2061.
The major impact in the Yucatan wiped out the dinosaurs about:
65 million years ago.
What is the typical size of most known asteroids?
a few kilometers
The nucleus, or main solid body, of a comet has a typical size of
a few kilometers.
The Perseid meteor shower gives us about a meteor every minute in mid
August.
Which of the following objects never collide with the Earth?
Amor asteroids
The most famous asteroid impact scar on Earth is located in
Arizona.
Nearly every aspect of astronomy is related in some way to the existence of gravity and to the motions which are responsible for a balance against gravity. How does this balance play a role for the miscellaneous objects of the solar system (i.e., the asteroids and comets)? How can some aspect of this be used as a tool to determine masses in the solar system? (SA)
Asteroids and comets all orbit the Sun, some with highly eccentric orbits. Some comets have periods of millions of years. Gravity acting on and between comets and asteroids can be used to determine their masses and the masses of bodies affecting them.
The type of asteroid that would appear darkest and reflect the least light is type
C.
The three largest asteroids are
Ceres, Pallas, and Vesta.
The largest Kuiper Belt body is
Eris.
On its way to Jupiter, Galileo also gave us close-ups of
Gaspra and Ida.
What is so unusual about Pluto's orbit?
It is more inclined to the ecliptic than any of the eight planets.
Compared to Ida, Eros, and Gaspra, what was odd about Mathilde?
It was less dense than rock, but more than ice, suggesting a porous structure.
Which statement about Pluto's discovery is FALSE?
It was the massive jovian Lowell described as "Planet X" in his calculations.
The orbital resonances with Jupiter are shown in the
Kirkwood Gaps.
From its orbit, we now recognize Pluto as the largest member of the
Kuiper Belt.
What arguments are cited for the existence of the Oort Cloud of comets? (SA)
Long-period comets have very large orbits that carry them out tens of thousands of A.U. away from the Sun. Kepler's second law tells us that the comets spend most of their time at these great distances. Because the direction of the orbit and its inclination appear random, all this implies a vast cloud of cometary objects surrounding the solar system; i.e. the Oort Cloud. Then in 2004 came the discovery of huge Sedna, the biggest solar system body found since Pluto; its orbit lies far beyond the Kuiper Belt, so it seems to belong to the Oort Cloud as well.
The two names most associated with the discovery of Pluto are
Lowell and Tombaugh.
The type of asteroid that would be the densest would be type
M.
The NASA orbiter that ultimately landed on the surface of the asteroid Eros was
NEAR Shoemaker.
Long period comets are thought to reside mainly in the
Oort Cloud.
When it was determined that Sedna, the largest body in the Solar System to be discovered since Pluto, has a perihelion distance that is three times further out than Pluto and such an eccentric orbit that it has a period of thousands of years, it was placed in the
Oort Cloud.
Why were the mass and density of Pluto unknown until Charon was found? (SA)
Pluto is so distant that its disk was not resolved well, and it had no discernable gravitational influence on Uranus and Neptune (Lowell's prediction was just luck). But Charon's orbit let us find the mass of both objects, and the series of eclipses allowed us to calculate the sizes of both bodies with great accuracy.
What are the Kirkwood Gaps? What role does Jupiter play? (SA)
They are regions within the asteroid belt where resonances with Jupiter, particularly at the 2:1 region, have cleared asteroids from that period and distance.
What is the defining property of the Trojan asteroids?
They have orbits at the distance of Jupiter and 60 degrees ahead of or behind it.
Pluto is most similar to
Triton.
How does the discovery of a comet typically differ from that of an asteroid? (SA)
While both bodies are in motion, and thus noted as streaks on time exposure photos and CCD images, comets typically do not become visible until they approach the Sun and develop a coma, so their images are often fuzzy. Many amateur discoveries of comets depend on this fuzzy appearance in telescopes.
The Apollo and Aten asteroids have orbits that
cross the orbit of Earth at perihelion.
The Amor asteroids have orbits that
cross the orbit of Mars, but not Earth, at perihelion.
What are comets made of?
dark colored complex hydrocarbons silicates and rocky dust metallic dust particles methane, ammonia, and water ice all of the above
The first hint of the role of asteroids in extinction of the dinosaurs came from
finding a layer of worldwide iridium enriched dust.
Charon's orbit
is highly inclined to Pluto's orbital plane.
The orbits of most comets
lie almost entirely beyond the orbit of Neptune.
The orbits of most asteroids
lie entirely beyond the orbit of Mars.
Which of the following objects would be found on the Moon's surface?
meteorites