According to Copernicus, Saturn could be seen in the middle of the night and during the day time, so Saturn must be ___.

• outside of Earth's orbit

• inside of Earth's orbit.

• between Earth and the Sun

• bigger than Earth

Kepler's law about "equal areas in equal time" tells us that orbiting objects

• move faster when they are closer

• have shorter periods when they have shorter average distance

• orbit in an ellipse

• have greater gravity when they are closer

Copernicus' important contribution to astronomy was

• proving planets move around the Sun in elliptical orbits
• the theory of gravity
• proposing a simpler model for the motions of planets in the solar system
• discovering the Sun was not at the center of the Milky Way

Which planet in our solar system will have the fastest orbital  speed?

• Venus 
• Earth 
• Saturn 
• Mercury 

As mass increases, gravity ________________.

• Increases 
• Decreases 
• Stays the same 

the path an object takes as it revolves around a star, planet, or moon

• revolve

• orbit

• rotate

• space probe

What did Kepler discover about planets and their orbital speed?

• Planets closest to the Sun will orbit with the fastest orbital speed.
• Planets with the greatest mass will orbit the Sun with the fastest orbital speed.
• Planets furthest from the Sun will orbit with the fastest orbital speed.
• Planets with the least mass will orbit the Sun with the fastest orbital speed.

What does heliocentric mean? 

• Earth centered
• Helium centered
• Sun centered
• Proof of the Big Bang

Which will have a bigger force of gravity on the Earth

• Jupiter because its big

• Saturn because it is far

• the Moon because its closest

• The Mercury because it is moving the fastest

Jupiter is much larger than its moon, Europa. The center of gravity between Jupiter and Europa is

• much closer to Jupiter (within Jupiter)

• much closer to Europa

• at Jupiter's core/center

• half way between to two.