Our world, other worlds

Mars has two moons named Phobos and Deimos, two Greek words meaning __________ and ___________.

• Blood and Gore

• Sword and Shield

• Wrath and Sorrow

• Panic and Fear

Mars once had running water that carved canyons and other features into its surface. What happened to the water?

• Mars is too far from the sun and cold to sustain water.

• Marsquakes caused all the water to seep into cracks in the crust.

• An asteroid clobbered Mars and vaporized the water. .

• Most of Mars’s water was lost to space or remains frozen in soil and ice caps.

Earth isn't the only body in the solar system with rivers and lakes. Which other world has similar features?

• Mercury (liquid lead)

• Saturn's moon Titan (liquid methane)

• Saturn (liquid oxygen)

• Neptune's moon Triton (liquid ammonia)

Earth and Venus are rocky planets of about the same size, but Earth's average surface temperature is about 59° F, while Venus' is 1,350° F, hot enough to melt lead or aluminum. Why the difference?

• Venus has a stronger greenhouse effect than Earth.

• Venus is made of denser rock than Earth.

• Earth is more geologically active than Venus.

• Ice caps and oceans on Earth absorb energy from the atmosphere.

Which circumstances could end life on Earth?

• The sun continues to heat up. In a billion years, Earth gets too hot, oceans evaporate, water vapor is “cooked out” of Earth’s crust and all life dies out.

• A massive asteroid smashes into Earth, vaporizing swaths of the surface and permanently changing the atmosphere.

• Both of the above

• None of the above.

Earth's magnetic field shields us from solar wind and helps hold onto the atmosphere and water. To what do we owe this invisible protector?

• The aurora borealis

• Plate techtonics

• Earth's circulating liquid metal core

• All of the above

Earth is the only body in the solar system thought to have oceans of liquid water.

• True

• False

Earth is smack in the middle of the "habitable zone" around the sun, where temperatures are right for liquid water to exist.

• True

• False

Exoplanets that have a lot of volcanic activity and exist in systems with many asteroids are bad prospects for looking for extraterrestrial life.

• True

• False

Small Earth-sized planets are common in the galaxy.

• True

• False