Chapter 12 (Part 2)
pea-size particle from a comet
A typical shooting star in a meteor shower is caused by a ________ entering Earth's atmosphere.
determining its mass from its gravitational pull on a spacecraft, satellite, or planet
If we know the size of an asteroid, we can determine its density by
dust injected into the stratosphere from the impact absorbed visible light from the Sun, causing global temperatures to plummet
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
rocky and primitive
Most meteorites are
once every hundred million years
On average, how often do impactors about 10 km in size, large enough to produce mass extinction, hit Earth?
contain a noticeable fraction of pure metallic flakes
Primitive meteorites can be distinguished from other meteorites and terrestrial rocks because they
chunks of a larger asteroid that was shattered by a collision
Processed meteorites with low metal content probably are
meteorite
What do we call a small piece of solar system debris found on Earth?
Pluto's moon
What is Charon?
a fragment of an asteroid from the solar system that has fallen to Earth's surface
What is a meteorite?
10 km
What is the typical size of comets that enter the inner solar system?
the plasma tail
What part of a comet points most directly away from the Sun?
inside of Jupiter's orbit
When do comets generally begin to form a tail?
about 80 years ago
When was Pluto discovered?
near the radius at which they orbit today
Where did comets that are now in the Kuiper belt originally form?
near the jovian planets
Where did comets that are now in the Oort cloud originally form?
discovery of Pluto's 3 moons
Which of the following Pluto observations did not help convince scientists to change Pluto's status from that of a planet?
The strength of gravity on small asteroids is less than the strength of the rock
Why aren't small asteroids spherical in shape?
It dredged up material that gave us our first direct look at Jupiter's interior composition
Why was the Shoemaker-Levy 9 impact so important to astronomers?
The two planets have an orbital resonance that prevents them from colliding
Why won't Pluto collide with Neptune?
