Astronomy Chapter 9

Which of the following statements is NOT true?objects in the Kuiper belt are made mostly of rock and metal.
A rock found on Earth that crashed down from space is called _____.a meteorite
The asteroid belt is located ________between the orbits of Mars and Jupiter
Which statement about asteroids is NOT true?If we could put all of the asteroids together, they would make an object the size of Earth
A typical meteor is created by a particle about the size of a _____________pea
What do we mean by a primitive meteorite?a piece of rock that is essentially unchanged since it first condensed and accreted in the solar nebula some 4.6 billion years ago
Among discovered meteorites, we have found some with all of the following origins except ________.being a fragment from Comet Halley
Which statement is NOT thought to be true of all comets in our solar system?comets always have tails
What direction do a comet’s dust and plasma tails point?generally away from the Sun
When a comet passes near the Sun, part of it takes on the appearance of a large, bright ball from which the tail extends. This part is called_________.the coma.
The total number of comets orbiting the sun is estimated to be about ___________1 trillion
What is Charon?the largest of Pluto’s three moons
According to current evidence, Pluto is best explained as ____________.a large member of the Kuiper belt
What is Eris?an icy object that orbits in the Kuiper belt and is larger than Pluto.
What was the shoemaker-Levy 9 impact?the 1994 impact of a chain of comet fragments into Jupiter
What do we mean by a mass extinction?the extinction of a large fraction of the world’s plant and animal species in a relatively short period of time
If the hypothesis tracing the extinction of dinosaurs to an impact is correct, the dinosaurs died off largely because ________.of global climate effects initiated by dust and smoke that entered the atmosphere after the impact
Which of the following statements best describes the size of the largest asteroid, Ceres?It is a little less than half the diameter of our Moon
If we could put all of the asteroids together, their total mass would be ________.much less than the mass of any terrestrial planet
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
Gaps in the asteroid belt (Kirkwood gaps) are caused by __________.orbital resonances with Jupiter
When you see a 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
Suppose you find a meteorite made almost entirely of metal. According to current science, which of the following statements might be true?Your meteorite is a fragment from the core of a large asteroid that shattered in a collision
Which of the following objects are probably not located in the same general region of the solar system in which they originally formed?Oort cloud comets
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.
When we see a meteor shower, it means that _________.Earth is crossing the orbit of a comet
Why won’t Pluto collide with Neptune?Pluto orbits the Sun exactly two times for every three times Neptune orbits, which ensures that they never come close together.
What is Pluto’s moon Charon thought to have in common with our own moon?It probably formed as the result of a giant impact
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 at the point in its orbit closest to the Sun.
The discovery of Eris _________.was not surprising, because other Kuiper belt objects approaching the size of Pluto had already been discovered.
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 rocks from the impacts
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.
Facts about asteroidsrocky leftovers of planet formations
largest: Ceres
small asteroids are more common
all of the asteroids together does not equal a terrestrial planet
potato shaped objected
cratered not round
Asteroid orbits:most asteroids orbit between Mars and Jupiter
Trojan asteroids follow Jupiter’s orbit.
Origin of Asteroid BeltRocky planetesimals between Mars and Jupiter did not accrete into a planet. Jupiter’s gravity with orbital resonance influence stirred up asteroid orbits and prevented their accretion into a planet
Meteorites:something that has already landed.

most meteorites are pieces of asteroids

Meteorstreak of light as an object falls
Primitive Meteorites:rock that hasn’t changed
Processed meteorites:younger, have experienced processes like volcanism or differentiation
Comet factsformed beyond the frost line
dirty snowball
most comets do not have tails
remain perpetually frozen
only comets that enter the inner solar system grow tails
Coma:atmosphere that comes from the nucleus
Nucleuspiece of ice
Plasma tailgas escaping from the coma, pushed by solar wind
Dust tailpushed by photons
Meteor showersComets eject small particles that follow the comet around in its orbit and cause meteor showers when Earth crosses comet’s orbit
Oort Cloudrandom orbits extending about 50,000 km

not from beginning of solar system.. byproduct of Jupiter… once closer to the sun.. kicked out by gravitational interactions with Jovian planets.

Kuiper Beltorderly orbits from 30-100 AU in disk of solar system

flat plane, aligned with the plane of planetary orbits, orbiting in the same direction as the planets

PlutoPluto’s orbit is tilted and elliptical
Neptune and Pluto prevented collisionNeptune orbits three times during the time Pluto orbits twice.. resonance prevents a collision
Is Pluto a Planet?smaller
not gas- ice
icy composition like a planet
elliptical, inclined orbit
more in common with comets
What is pluto like?very cold
five moons… largest- Charon
thin nitrogen atmosphere that refreezes onto the surface as Pluto’s orbit goes farther from Sun.