Ask Ethan #71: Heavy planets, light Sun? (Synopsis)

“The single most powerful element of youth is our inability to know what’s impossible.” -Adam Braun

"I'm going to be a star," says every clump of matter in a molecular cloud, as it prepares to collapse under the tremendous pull of gravitation. But try as they might, only a small fraction of that gas and of those clumps -- the largest and earliest, preferentially -- will ever get there.

This week's Ask Ethan question is one of the shortest and sweetest out there, and comes from Greg Rogers:

If the Sun (and all stars) are mostly Hydrogen and Helium, why don’t planets have about the same distribution of stuff?

They formed from the same things, so why not?

Image credit: © 1998–2015 Lynette R. Cook. Image credit: © 1998–2015 Lynette R. Cook.

The answer is an incredible story of gravity, heat, and mass.

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By david hurn (not verified) on 22 Jan 2015 #permalink