Astronomy Test 3 - The Terrestrial Planets 3/5/03 ctr

Please put your name on the back of the last sheet only.

Matching - Place the best answer in the blank provided. Answers may of course be used more than once. (Two points each)

The Terrestrial Planets

___ Hottest planet 1-Mercury
___ Closest in size to Earth
___ Has two captured asteroid moons 2-Venus
___ Nearest the sun
___ Polar caps of carbon dioxide ice 3-Earth
___ Most like Earth's moon
___ 75% covered with water 4-Mars
___ Largest volcano
___ Reddest planet
___ Mapped only by radar
___ Once had lots of water which is now apparently gone
___ Polar caps of 100% water ice
___ Has the highest atmospheric pressure
___ Visited by Viking landers
___ Has no atmosphere
___ Most features named after women
___ Largest canyon
___ Very thin atmosphere, mostly CO2
___ Explored by Russian Venera landers

Multiple choice - 3 each (above were 2)

___ On which planet would you not expect to find craters?

___ The Kuiper belt refers to a group of objects orbiting
1-between the orbits of Mars and Jupiter.
2-beyond Neptune's orbit.
3-just within Earth's orbit.
4-nearly halfway to the next star.

___ In general, the planets with high densities are found
1-at the very edge of our solar system.
2-greatly spread apart.
3-very close together.
4-near the outermost planets.

___ Moons around the outer planets that orbit OPPOSITE the direction the planet spins were probably
1-formed by collisions with the central planet itself.
2-captured moons.
3-hit by large asteroids in the early solar system.
4-formed at the same time as the planet.

___ The majority of comets reside
1-just beyond the orbit of Mars.
2-just beyond the orbit of Mercury.
3-as far as nearly halfway to the next star.
4-just beyond the orbit of Neptune.

___ If another interstellar cloud, exactly like the one that formed our solar system, existed, it would form
1-a planetary system with different-sized planets at different distances.
2-an identical planetary system to our own.
3-a double-star system that might have planets.
4-a central star, but no planets.

___ Which of the following have had the most influence on the surface of the Moon?
1-impact cratering

___ Observations of the Moon show that the lunar maria have only 3% as many craters as the lunar highlands. It can be reasoned that
1-lunar lava flowed across the surface BEFORE most of the Moon's larger craters were created.
2-unar lava flowed across the surface AFTER most of the Moon's larger craters were created.
3-the lunar maria must be about 4.6 billion years old.
4-comets have collided with the Moon more often than with Earth.

___ Which of the following are not signs of tectonic activity?
1-The African rift valleys
2-The Grand Canyon in Arizona.
3-Mt. Fuji in Japan.
3-The Swiss Alps.

___ The greenhouse effect is caused by
1-infrared radiation being trapped in the troposphere.
2-heat being released through the ozone hole.
3-slow changes in the position of the continents.
4-Earth's magnetic field.

___ Hydrogen and helium are the most common atoms in the universe. Despite this, they are not found at all in the atmospheres of the terrestrial planets. This is because
1-hydrogen and helium are both dissolved in the oceans.
2-volcanoes on Earth do not outgas hydrogen or helium.
3-hydrogen and helium both quickly escape into space.
4-hydrogen and helium are locked up in rocks in the Earth's surface and interior.

____ The water that once was present on Mars may now be
1-frozen underground
2-in the polar caps
3-lost to interplanetary space
4-all of these

Short answer - 6 points each - previous were 3.

1. (a) Why did astronomers in the year 1900 expect Venus to be much like Earth?

(b) What are the actual temperature and pressure on Venus?

2. What does the "greenhouse effect" do to the earth? How could too much of it harm us?

3. (a) What did the canals on Mars turn out to be?

(b) What evidence is there that Mars once had lots of water?

4. If Mars were twice its present diameter, it would probably be much more like Earth. Why?

5. If we found oxygen in the atmosphere of a planet circling another star, why would this be good evidence that life existed on that planet?

6. A moon rock was returned from the moon and analyzed. It was found that the ratio of potassium -40 to argon-40, potassium's radioactive decay product, was 1 to 4. If the half life of potassium-40 is 1.3 billion years, how old is the rock?

7. Why does Titan have an atmosphere thicker than Earth's, yet Mercury, which is the same size, has no atmosphere?