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Post  Post subject: Size of rocky planets  |  Posted: Sun Jan 10, 2016 7:03 pm
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Joined: Tue Feb 19, 2013 5:02 pm
Posts: 281

How large could a rocky planet be? It seems that at some point the planet would hold onto too much gas to be a rocky planet. Even figuring lower average density than the Earth I would think there is a point of no return from being a mini Neptune at least...

Post  Post subject: Re: Size of rocky planets  |  Posted: Sun Jan 10, 2016 10:15 pm
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Joined: Thu Aug 04, 2011 8:35 pm
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Location: Cardiff, Wales

not totally sure, but it's not only size that matters, but also how close it is to its sun + how strong the sun shines
after all, the T Tauri wind early in a star's life blows a lot of the inner planets atmosphere away + afterwards its solar strength defines whether water will appear as ice, liquid or vapour, or a combination of all three

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Post  Post subject: Re: Size of rocky planets  |  Posted: Sun Jan 10, 2016 10:49 pm

Joined: Wed Sep 02, 2015 7:34 pm
Posts: 217

Good question. I was able to find some info:

http://www.universetoday.com/13757/how- ... anets-get/
What’s the largest possible rocky planet? For this I put in an email to Dr. Sean Raymond, a post doctoral researcher at the Center for Astrophysics and Space Astronomy (CASA) at the University of Colorado. Here’s what he had to say: “The largest “terrestrial” planet is generally considered the one before you get too thick of an atmosphere, which happens at about 5-10 Earth masses (something like 2 Earth radii). Those planets are more Earth-like than Neptune-like.”

The term Super-Earth also is used by astronomers to define planets bigger than Earth-like planets (from 0.8 Earth-radii till 1.25), but smaller than mini-Neptunes (from 2 Earth-radii till 4).[7] This definition was made by the Kepler Mission.

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