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Unit 3, Lesson 4
Vocabulary
Term | Definition |
---|---|
Terrestrial Planet | A terrestrial planet, telluric planet or rocky planet is a planet that is composed primarily of silicate rocks or metals. Within the Solar System, the terrestrial planets are the inner planets closest to the Sun. |
Astronomical Unit | A unit of measurement equal to 149.6 million kilometers, the mean distance from the center of the earth to the center of the sun. |
Prograde Rotation | Having a rotational or orbital movement that is the same as most bodies within a celestial system. In our solar system, prograde movement for both rotating and orbiting bodies is in a counterclockwise direction when viewed from a vantage point above the E |
Retrograde Rotation | All eight planets in the Solar System orbit the Sun in the direction that the Sun is rotating, which is counterclockwise when viewed from above the Sun's north pole. Six of the planets also rotate about their axis in this same direction. The exceptions—th |
Gas Giant | A large planet of relatively low density consisting predominantly of hydrogen and helium, such as Jupiter, Saturn, Uranus, or Neptune. |
Planetary Ring | A planetary ring is a disk or ring of dust, moonlets, or other small objects orbiting a planet or similar body. The most notable planetary rings in the Solar System are those around Saturn, but the other three gas giants (Jupiter, Uranus and Neptune) also |
Dwarf Planet | A celestial body resembling a small planet but lacking certain technical criteria that are required for it to be classed as such. |
Kuiper Belt | A region of the solar system beyond the orbit of Neptune, believed to contain many comets, asteroids, and other small bodies made largely of ice. |