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Science Ch 5
Term | Definition |
---|---|
planets | Any large body orbiting any star “wanderer” |
perihelion | The point in a planet’s orbit at which a it is nearest to the sun |
aphelion | The point in a planet’s orbit at which a it is furthest from the sun |
Astronomical unit (a.u.) | The earth’s average distance to the sun = 1a.u. |
mass | A measure of the amount of matter something contains |
weight | The force of gravity exerted on an object |
Surface gravity | The downward pull the planet exerts on objects at its surface |
Inferior Planets | Planets closer to the sun than earth; mercury and Venus |
Phase | (of a planet): the amount and shape of the planet’s illuminated surface that is visible from the earth. |
transits | A planet passes directly between the earth and the sun so that we see its dark silhouette against the sun’s bright disk |
Superior Planets | Planets whose orbits are further from the sun than earth’s orbit |
Retrograde motion | The planet appears to move backward compared to the background stars |
Terrestrial planets | “Earthlike”, Mercury, Venus, Mars |
Jovian | Jupiterlike planets |
Gas giants | One of the large, gaseous planets |
Mercury | the fastest revolving planet |
Kepler | developed three laws of planetary motion |
Jupiter | the largest planet in our solar system |
Mars | the red planet |
ellipse | shape of planet's orbit |
albedo | a planet's reflectivity |
SETI | the program for identifying radio transmissions from intelligent alien races |