Space Science
Points to Remember
Points to Remember
- Rotation is the spinning of earth on its axis, which causes day and night. It takes earth 24 hours (one day) to complete one rotation.
- Revolution is earth’s motion around the sun; it takes Earth 365.25 days (one year) to complete one revolution around the sun.
- Earth’s axis is tilted 23.5˚ to the plane of its orbit. The northern end of Earth’s axis (the North Pole) points toward the North Star. The seasons are caused by the tilt of Earth’s axis as it revolves around the sun. This tilt causes the sun’s vertical rays to strike Earth farthest north on June 21 and farthest south on December 21.
- Our solar system consists of the sun, the planet, satellites, asteroids, meteoroids, and comets. The sun is at the center; its gravity keeps all other members of the solar system orbiting around the sun.
- The universe contains trillions of stars most clustered together in galaxies. Yet most of the universe is considered to be empty space. Our sun is a n average star, one of 800 billion stars clustered in a spiral galaxy called the Milky Way.