What is the difference between a star and a planet?

Baloo55th

Very simply - a star shines with its own light - a planet doesn't. More to it, of course, as some old burnt out stars don't really shine, but no planets do. If they do, they're stars. Stars are nuclear fusion furnaces of various types, while planets usually (there may be some that don't) orbit round them. As in The Sun (our nearest star) and The Earth (third planet out from the centre.). Planets may be rocky (us) or gassy (Jupiter, probably). Not big enough to get the reactions going, planets aren't. Aug 18 03, 3:21 PM

lothruin

*singing loudly* "The sun is a mass of incandescent gas, a gigantic nuclear furnace... where hydrogen is built into helium at a temperature of millions of degrees. The sun is hot, the sun is not, a place where we can live. But here on Earth, there'd be no life without the light it gives!" Baloo is so right. Stars are self-luminous, while planets are not. Aug 18 03, 6:35 PM

Gnomon

But in ancient times, the word planet meant a slightly different thing. It meant a light in the sky that moved relative to all the other lights. By this definition, the sun and moon were also considered to be planets. So sometimes you will see references to the sun as a planet in books discussing ancient astronomy. Aug 19 03, 2:15 AM

sequoianoir

As Gnomon has said, and as I'm sure most people know, re PLANET ("It meant a light in the sky that moved relative to all the other lights"). Planet means WANDERER (from Middle English - Old French - Late Latin - Greek -planasthai , to wander) Aug 19 03, 5:22 AM