Where Do Planets Come From?

For a long time nobody knew the answer to this question.  There were two main theories of planet formation.  Immanuel Kant (and Laplace, and a whole passel of others) figured planets condensed out of a disk of gas and dust swirling around a young star.  Before the Galaxies were identified as such, they were sometimes identified by astronomers as star systems in the process of formation.

The second theory was a bit more catastrophist in nature -- near encounters of stars pulled out material which then condensed into planets.  This theory always seemed a little improbable, and it had the depressing corollary that planetary systems would be vanishingly rare.

But nobody really knew the answer.  Even the discovery of extrasolar planets didn't really settle the issue -- it did demonstrate that planetary systems are common, but didn't tell us anything about how they form.  Astronomy is one of those irritating sciences in which one can't run controlled experiments to test your hypotheses.  The Kant-Laplace "nebular" hypothesis was the default assumption, but only because nobody could think of anything better. 

Well now we know.  The venerable Hubble Space Telescope has observed a disk of gas and dust with at least one planet embedded in it, orbiting Epsilon Eridani.

Epsilon Eridani is best known in fiction as the home of Babylon 5.  The Hubble observations suggest it might be a rather cluttered neighborhood for a space station.  No wonder the first four failed.

Comments

[Cori]

This is not helpful

[vicky oceguera]

i got a project 2 do and this didnt help me out at all =(

[te atahaia]

realy dumb info not realy giving u infomation about where they come from

[Cambias]

Do your own god-damned homework, kids.