Io, Europa, Ganymede, and Callisto are called the _____________ .
Galilean moons
Which planets have a small amount of methane in their atmospheres?
Uranus, Neptune
Which planets have atmospheres composed of hydrogen and helium gases?
Jupiter, Saturn, Uranus, Neptune
Which planet has a tilted axis of rotation?
Uranus
Which planet has the largest and most complex ring system?
Saturn
Which planet takes 165 years to orbit the Sun?
Neptune
Which planet has a core that might be the size of Earth and ten times its mass?
Jupiter
Why does Mercury not have an atmosphere?
gravity not strong enough to hold gases close to its surface
Which two metals make up the core of Mercury?
Iron and Nickle
What causes great dust storms on Mars that last for months?
Winds on Mars sometimes produce great dust storms
Why is Venus the hottest inner planet?
Its atmosphere traps a lot of heat energy.
Earth is the only planet with a wide variety of life because of its
moderate temperature and liquid water.
