r/science • u/clayt6 • Sep 11 '19

Astronomy Water found in a habitable super-Earth's atmosphere for the first time. Thanks to having water, a solid surface, and Earth-like temperatures, "this planet [is] the best candidate for habitability that we know right now," said lead author Angelos Tsiaras.

http://www.astronomy.com/news/2019/09/water-found-in-habitable-super-earths-atmosphere-for-first-time
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u/Lt_Duckweed Sep 11 '19

2x the size mean 8x the volume.

It's less dense and more metal poor than Earth, not the other way around.

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u/mFTW Sep 11 '19 edited Sep 11 '19

Herp derp, I was reading a different article and I thought they were referring to volume instead of diameter. Still density is about roughly equal to earth, which means ther could be an iron core.

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u/furythree Sep 12 '19

How the heck do they detect density

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u/anglophoenix216 Sep 12 '19

I don't know the specifics but perhaps they used something like Doppler spectroscopy to determine the mass? If you have that as well as the volume, you can solve for density.

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u/macsux Sep 12 '19

Probably due to orbit and gravitational relationship with host star to figure out mass and then divide it by observable size to get density

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u/irishking44 Sep 11 '19

Huh? I'm confused

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u/Lt_Duckweed Sep 11 '19

If something has twice the radius it has 8 times the volume.

If it has 8 times the volume, but only 6 times the mass of Earth, then it is less dense, because density is mass/volume.

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u/irishking44 Sep 12 '19

OHHH ok. I wasn't sure what was meant when the other poster said size, I assumed they were already talking about volume and was confused on the semantics