Question | Answer |
astronomy | the study of all physical objects beyond the Earth's atmosphere |
calendar | system for organizing time based on astronomical observations |
year | time needed for a planet to make one complete orbit around the sun |
revolution | one complete orbit |
How long does it take earth to make one revolution | 365.242 days |
What is our calendar called? | Gregorian |
Leap year | happens every four years, add 1 day to calendar |
Month | time needed for moon to orbit the Earth |
day | time needed for a planet to turn itself on its axis of rotation |
Angle of earth's rotation | 235 degrees |
How long does it take for the earth to make one rotation? | 24 hours |
Why do we have day and night? | only half the Earth can face the sun and have daylight |
Ptolemy | Geocentric model- earth is center of universe |
Copernicus | Heliocentric- sun is the center of the universe |
Brahe | Believed that planets revolve around sun, but sun and moon revolve around Earth |
Kepler | believed that planets revolve around sun in elliptical orbits |
Galileo | first person to use telescope |
Newton | Gravity is the force that keeps all objects in orbit |
Newton's law of universal gravitation | the higher the gravity, the more mass or the closer objects are together |