Today, most people live on .........
Earth
........... is often called "the Red Planet." It's the 4th planet from the sun.
Mars
You can recognize ........... by its yellow clouds. It's the 2nd planet from the sun.
Venus
Human can't live on some planets because they don't have enough ......... to breathe.
Oxygen
............. pulls us down to the ground.
Gravity
You will be very cold in space because the ........... is very low.
Temperature
Many scientists want to work on a .......... because it has a great view of the stars.
Space Station
