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The
Solar System Intro
to Astronomy Archaeoastronomy Time & Its Measurement Telescopes
The Earth
The Moon
Mecury,
Venus, Mars
The
Outer Planets
Solar
System Debris
The
Sun
Intersteller
Matter
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Solar System Terminology Planet: A natural satellite of the sun or another stellar system. Astronomical Unit (AU): The earth-sun distance, equal to 93 million miles (150 million km). Orbital Period of a planet: Inclination with respect to orbit: The tilt of a planet's orbital plane with respect to the orbital plane of the earth (ecliptic). Eccentricity: The "ovalness" of an elliptical orbit. It is precisely defined as the distance between the foci of an ellipse divided by the major axis, or the distance between one focus and the center of the ellipse divided by the semi-major axis of the ellipse. Rotational period: The amount of time a body requires to make one complete spin about its axis. Axial tilt: The inclination of the imaginary line about which a planet rotates to the perpendicular of the planet's orbital plane. Mass: The quantity of matter an object contains. Radius: Distance measured from the center to any point along the boundary of a circle or sphere. A sphere's volume equals 4/3 p (r)3. Average density: total mass divided by total volume Surface gravity: The force of attraction acting on a less massive object at the radius of a more massive body. Natural satellite: A body of lesser mass, formed without human intervention, revolving about a planet (or object) of greater mass. |