Lesson 10 Flashcards
What do asteroids and comets have in common?
Most are unchanged since their formation in the solar nebula
What is the size of the largest asteroid?
1000 km
How does the largest asteroid, Ceres, compare in size to other solar system worlds?
It is about a quarter the size of the Moon
Which is closest to the average distance between asteroids in the asteroid belt?
1 million km
Where are the Trojan asteroids located?
Along Jupiter’s orbit, 60° ahead of and behind Jupiter
We know that there are large gaps in the average distances of asteroids from the Sun (within the asteroid belt) because we
have plotted distributions of the orbital radii of the asteroids
Why do we sometimes observe asteroids at the distances of the gaps in the asteroid belt?
A gap is located at an average orbital distance, and asteroid orbits often have large eccentricities
How can we determine an asteroid’s reflectivity?
by comparing its infrared thermal emission to its visible-light reflection
If we know the size of an asteroid, we can determine its density by
determining its mass from its gravitational pull on spacecraft, satellite, or planet.
A typical shooting star in a meteor shower is caused by a ________ entering Earth’s atmosphere.
pea-size particle from a comet
Processed meteorites with low metal content probably are
chunks of a larger asteroid that was shattered by a collision
When do comets generally begin to form a tail?
inside of Jupiter’s orbit
here did comets that are now in the Oort cloud originally form?
near the jovian planets
Where did comets that are now in the Kuiper belt originally form?
near the radius at which they orbit today
The number of comets in the Oort cloud is probably about
a trillion
Why won’t Pluto collide with Neptune?
The two planets have an orbital resonance that prevents them from colliding
In the asteroid impact theory of the extinction of the dinosaurs some 65 million years ago, the dinosaurs (and over half of all the other species on Earth at that time) died off largely because
dust injected into the stratosphere from the impact absorbed visible light from the Sun, causing global temperatures to plummet.
Which of the following Pluto observations did not help convince scientists to change Pluto’s status from that of a planet?
discovery of Pluto’s 3 moons
Which statement is not thought to be true of all comets in our solar system?
Comets always have tails
What was the Shoemaker-Levy 9 impact?
the 1994 impact of a chain of comet fragments into Jupiter
Suppose there were no solar wind. How would the appearance of a comet in our inner solar system be different?
It would have only one tail instead of two
Suppose we discover a new comet on an orbit that brings it closer to the Sun than Mercury every 125 years. What can we conclude?
It has been on its current orbit for only a very short time compared to the age of our solar system
Why won’t Pluto collide with Neptune?
Pluto orbits the Sun exactly 2 times for every 3 Neptune orbits, which ensures they never come close together
Which of the following is not a piece of evidence supporting the idea that an impact caused the mass extinction that occurred 65 million years ago?
Fossilized dinosaur bones contain fragments of rock from the impact.
