AST CHAPTER 12
According to this graph, the minimum size of an object that could cause a mass extinction is a little less than _____.
10 km
How can we determine the reflectivity of an asteroid?
By comparing its brightness in visible light to its brightness in infrared light.
When we see a meteor shower, it means that _________.
Earth is crossing the orbit of a comet
Based on this graph, which statement below most accurately describes the impacts we should expect on Earth during the coming year?
Earth will be hit by at least one object a few meters in diameter, along with many smaller objects.
Listed following are some distinguishing characteristics of comets, meteors, and asteroids. Match these to the appropriate category of objects. *COMETS*
Form a coma when near the sun// most are located either in Kuiper belt or Oort Cloud// visible in the sky as a fuzzy patch of light that rises and sets with the stars.
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.
Why didn't a planet form where the asteroid belt is now located?
Gravitational tugs from Jupiter prevented material from collecting together to form a planet
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.
What is Pluto's moon Charon thought to have in common with our own Moon?
It probably formed as a result of a giant impact.
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.
Which of the following statements best describes the size of the largest asteroid, Ceres?
Its diameter is a little larger than a quarter the diameter of our Moon.
Suppose that large jovian planets had never formed in our solar system. Which of the following would most likely be true?
Neither the asteroid belt nor Oort cloud would exist.
The impact of a 100-meter object will not cause "widespread" devastation, but it could still kill millions of people if it struck a major city. In Part C, you found that the probability of such an impact in any single year is only 1 in 1000. Suppose we learn that it has already been 1200 years since the last such impact. What would that tell us?
Nothing; we would still presume that the chance of such an impact during the next year is 1 in 1000.
Which of the following objects are probably not located in the same region of the solar system in which they originally formed?
Oort cloud comets
Which of the following is not a piece of evidence supporting the idea that Pluto is a large comet of the Kuiper belt?
Pluto grows a coma and a long tail when it is at the point in its orbit closest to the Sun.
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.
Listed following are some distinguishing characteristics of comets, meteors, and asteroids. Match these to the appropriate category of objects. *ASTEROIDS*
Typically orbit the Sun at approx. 3 AU// compositions similar to that of the terrestrial planets.
Listed following are some distinguishing characteristics of comets, meteors, and asteroids. Match these to the appropriate category of objects. *METEORS*
Visible in the sky as a bright streak of light for only a few seconds// dust particles entering Earth's atmosphere at high speed.
Can an asteroid be pure metal?
Yes, it must have been the core of a shattered asteroid.
Suppose you find a meteorite made almost entirely of metal. According to current science, which of the following statements must be true?
Your meteorite is a fragment from the core of a large asteroid that shattered in a collision.
What does Pluto most resemble?
a comet
What is the probability that an object 100 meters in diameter will hit Earth during the coming year?
about 1 in 1000
According to the graph, an object 10 kilometers across hits Earth __________.
about once every 100 million years
If we could put all the asteroids together, their total mass would be ______.
much less than the mass of any terrestrial planet
Gaps in the asteroid belt (often called Kirkwood gaps) are caused by ______.
orbital resonances with Jupiter
When you see the bright flash of a meteor, what are you actually seeing?
the glow from a pea-size particle and the surrounding air as the particle burns up in our atmosphere
In science fiction movies, spaceships are often shown dodging through large numbers of closely spaced, boulder-size objects. Which of the following real things in our solar system would look most like such science fiction dangers?
the rings of Saturn
The discovery of Eris __________.
was not surprising, because other Kuiper belt objects approaching the size of Pluto had already been discovered
