What is a Planet?

The answer to this question is a highly controversial one. This has not always been the case, though. In fact, before 1978 the definition of a "planet" was not really necessary. Until that time a planet simply meant a body in orbit around the Sun, that reflected sunlight, and was not a planetary moon, asteroid, or comet.

Planet          Distance From The Sun                     Diameter
Mercury     57,910,000 km (0.387 AU)               4,879 km
Venus         108,200,000 km (0.723 AU)             12,104 km
Earth          149,600,000 km (1.000 AU)             12,756 km
Mars           227,940,000 km (1.524 AU)              6,805 km
Jupiter       778,330,000 km (5.203 AU)              142,984 km
Saturn       1,424,600,000 km (9.523 AU)          120,536 km
Uranus      2,873,550,000 km (19.208 AU)         51,118 km
Neptune    4,501,000,000 km (30.087 AU)        49,528 km
Pluto           5,945,900,000 km (39.746 AU)       2,368 km

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Earth Facts

Jupiter Facts

Mars Facts

Mercury Facts

Moon Facts

Neptune Facts

Pluto Facts

Saturn Facts

Sun Facts

Uranus Facts

Venus Facts