Question | Answer |
geocentric | an model of the universe in which Earth is at the center of the revolving planets and stars |
heliocentric | a model of the universe in which Earth and the other planets revolve around the sun |
ellipse | an oval shape which may be elongated or nearly circular |
moon | a natural satellite that revolves around a planet |
astronomical unit | a unit of measure used to express distance in space; 1 = Earth's average distance from the sun (150 million kilometers) |
How did Copernicus contribute to our knowledge of the solar system? | Copernicus worked out the arrangement of the known planets and how they move around the sun; polish astronomer who, in 1543, further developed the heliocentric model |
How did Galileo contribute to our knowledge of the solar system? | Galileo used the newly invented telescope to make discoveries that supported the heliocentric model; for example he discovered four moons revolving around Jupiter and that Venus goes through a series of phases similar to thoses of Earth's moon |
How did Kepler contribute to our knowledge of the solar system? | Johannes Kepler, the assistant of Danish astronomer Tycho Brahe, used his boss's data to develop three laws that describe the motions of the planets |
What objects make up the solar system? | today we know that the solar system consists of the sun the planets and their moons, and several kinds of smaller objects that revolve around the sun |
How did Ptolemy contribute to our knowledge of the solar system? | early Greek astronomer who thought that the Earth was the center of a system of planets and stars, and explained that the planets move on small circles that move on bigger circles |
What were Kepler's Laws? | 1.the orbit of each planet is an ellipse; 2.each planet moves faster when it is closer to the sun and slower when it is farther away from the sun; 3.planets closer to the sun orbit the sun faster than the planets that are farther away from the sun |