Earth has one moon, which revolves around it. Earth is a planet in our solar system. Currently we know of nine planets in our solar system. The sun is the center of our solar system. Planets rotate on an axis as they revolve around the sun.
Gravity is a force that pulls objects toward the earth.
Astronauts need to adapt to living and working in space. Space technology has changed over time. Space technology is used in everyday life. Our understanding of space is constantly changing. Green, orange and purple are secondary colors.