<p>I'm guessing that real data about exoplanets will be unhelpful because it's hard to detect low-mass planets, and thus answers are likely to be based on the kind of educated-guesswork that we relied on for decades when we really only knew about planets in the solar system.</p>
<p>[Edit]</p>
<ul>
<li><p><strong>&quot;No atmosphere&quot;</strong></p>
<p>I'm looking for things like Earth's Moon, or Mars, about which <a href="https://en.wikipedia.org/wiki/Atmosphere_of_Mars" rel="nofollow noreferrer">Wikipedia</a> says:</p>
<blockquote>
<p>The average surface pressure [of Mars] is only about 610 pascals (0.088 psi) which is less than 1% of the Earth's value.</p>
</blockquote>
<p>So, surface pressure no greater than 1% of Earth's atmosphere.</p>
</li>
</ul>

CC BY-SA 4.0
2023-01-26T23:49:16.873Z
This is currently impossible to answer - a Superearth with a Venusian atmosphere would look the same as a bare core in transit spectroscopy. Ground based high resolution spectro might do the trick when the extremely large telescope come online.
AtmosphericPrisonEscape
CC BY-SA 4.0
2023-01-31T12:43:32.350Z
In near future, NASA Roman space telescope is planned to make gratational microlensing studies. There is hope it will constrain the abundances of small (mars-sized and below) exoplanets.
Heopps
CC BY-SA 4.0
2023-01-31T17:01:22.687Z
@Tom For a recent look with James Webb, see this paper on the arxive: https://ui.adsabs.harvard.edu/abs/2023arXiv230104191L/abstract  Even for a $1 R_{\oplus}$, 1 $m_{\oplus}$ planet at only 12.5 pc distance, with the best instrument available, we cannot distinguish whether what we see is a thick, cloudy Venus-like atmosphere or bare rock.
AtmosphericPrisonEscape
<exoplanet><planetary-atmosphere>
How common are exoplanets with no atmosphere?
Tom
# How common are exoplanets with no atmosphere?

(Asked by: username_0 on 2023-01-26)

I'm guessing that real data about exoplanets will be unhelpful because it's hard to detect low-mass planets, and thus answers are likely to be based on the kind of educated-guesswork that we relied on for decades when we really only knew about planets in the solar system.

[Edit]

* **"No atmosphere"**

  I'm looking for things like Earth's Moon, or Mars, about which [Wikipedia](https://en.wikipedia.org/wiki/Atmosphere_of_Mars) says:

  > The average surface pressure [of Mars] is only about 610 pascals (0.088 psi) which is less than 1% of the Earth's value.

  So, surface pressure no greater than 1% of Earth's atmosphere.

**Tags:** exoplanet, planetary-atmosphere

> **Comments:**
> **username_1**: This is currently impossible to answer - a Superearth with a Venusian atmosphere would look the same as a bare core in transit spectroscopy. Ground based high resolution spectro might do the trick when the extremely large telescope come online.  
> **username_2**: In near future, NASA Roman space telescope is planned to make gratational microlensing studies. There is hope it will constrain the abundances of small (mars-sized and below) exoplanets.  
> **username_1**: @username_0 For a recent look with James Webb, see this paper on the arxive: https://ui.adsabs.harvard.edu/abs/2023arXiv230104191L/abstract  Even for a $1 R_{\oplus}$, 1 $m_{\oplus}$ planet at only 12.5 pc distance, with the best instrument available, we cannot distinguish whether what we see is a thick, cloudy Venus-like atmosphere or bare rock.  

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## 0 answers

