<p>A major factor, is that Venus' volcanoes are still active. Mars's died millions of years ago. If they were still erupting, then Mars' atmosphere would be much thicker today.</p>
<p>Edit: This may actually be true as referenced by a paper published July 20 2020 cited below.</p>
<p>Gülcher, A.J.P., Gerya, T.V., Montési, L.G.J. et al. Corona structures driven by plume–lithosphere interactions and evidence for ongoing plume activity on Venus. Nat. Geosci. (2020). <a href="https://doi.org/10.1038/s41561-020-0606-1" rel="noreferrer">https://doi.org/10.1038/s41561-020-0606-1</a></p>
<p>Also see in Phys.org:</p>
<ul>
<li><a href="https://phys.org/news/2020-07-scientists-volcanoes-venus.html" rel="noreferrer">Scientists discover volcanoes on Venus are still active</a> discussed the above Nat. Geosci.</li>
<li><a href="https://phys.org/news/2020-01-scientists-evidence-venus-volcanoes.html" rel="noreferrer">Scientists find evidence that Venus has active volcanoes</a></li>
</ul>

CC BY-SA 3.0
2016-09-15T04:07:47.713Z
Sounds about right, but can you expand this answer a little? Now it  is more of a comment.
SE - stop firing the good guys
CC BY-SA 3.0
2016-10-24T10:07:02.657Z
Still, it's a pretty cool comment!  :)
Fattie
CC BY-SA 4.0
2018-11-10T19:12:11.223Z
Downvote: This is not known. There are indications that the surface might be young (~30 million yrs) but except for counting of large craters there is no data available on the age of the surface.
AtmosphericPrisonEscape
CC BY-SA 4.0
2024-05-16T02:57:30.973Z
@AtmosphericPrisonEscape, data *is* available, in the form of changes between the [three *Magellan* mapping passes](https://en.wikipedia.org/wiki/Magellan_(spacecraft)#Orbital_encounter_of_Venus).
Mark
CC BY-SA 4.0
2016-09-15T01:31:09.703Z
2020-07-21T02:14:16.857Z
2020-07-21T02:14:16.857Z
JDL
<p>Venus has a strong ionosphere that protects it against violent solar winds. So, even though Venus has no intrisic magnetic field, it has an effective, induced magnetic field due to the interaction between the solar winds and the atmosphere, that protects it against solar winds.</p>

<p>Venus atmosphere is thick enough to have a consequent ionosphere, that would be the difference between Mars and Venus (and Venus was able to keep a thicker atmosphere due to its greater mass, contrary to Mars).</p>

<p><strong>Sources:</strong></p>

<ul>
<li><a href="http://www-ssc.igpp.ucla.edu/personnel/russell/papers/venus_mag/">Luhmann &amp; Russell (1997)</a>,  on Venus</li>
<li><a href="http://www-ssc.igpp.ucla.edu/personnel/russell/papers/mars_mag/">Luhmann &amp; Russell (1997)</a>,  on Mars</li>
</ul>

CC BY-SA 3.0
2016-06-19T23:27:40.043Z
I believe I read somewhere that the character of Venus's atmosphere has been changed over the eons. Water in the atmosphere was split into separate hydrogen and oxygen atoms, with the hydrogen being blown into space by the solar winds. This makes Venus not only hot, but dry. I wonder if Earth might have benefited by capturing some of the hydrogen and matching it up with free oxygen in our atmosphere.
Howard Miller
CC BY-SA 3.0
2013-10-14T14:56:26.140Z
2013-10-14T14:56:26.140Z
MBR
<p>This <a href="https://space.stackexchange.com/a/635/58">answer</a> on Space Exploration to a question about Mars says that one reason Mars has such a thin atmosphere is because it lacks a magnetic field to protect it from the effect of double solar winds.</p>
<p><a href="https://astronomy.stackexchange.com/a/636/6">Here</a> MBR explains that Venus does not have a magnetic field.</p>
<p><img src="https://sci.esa.int/documents/34571/35316/1567217260900-VenusSurface-410.jpg" alt="Venus-atmopshere" /></p>
<p><sub>Image credit: ESA</sub></p>
<p>If this is the case, then why has Venus's atmosphere not been stripped away by solar wind like that of Mars?</p>

<planetary-atmosphere><magnetic-field><venus><solar-wind>
Why has Venus's atmosphere not been stripped away by solar wind?
called2voyage
# Why has Venus's atmosphere not been stripped away by solar wind?

(Asked by: username_0 on 2013-10-14)

This [answer](https://space.stackexchange.com/a/635/58) on Space Exploration to a question about Mars says that one reason Mars has such a thin atmosphere is because it lacks a magnetic field to protect it from the effect of double solar winds.

[Here](https://astronomy.stackexchange.com/a/636/6) username_6 explains that Venus does not have a magnetic field.

![Venus-atmopshere](https://sci.esa.int/documents/34571/35316/1567217260900-VenusSurface-410.jpg)

Image credit: ESA

If this is the case, then why has Venus's atmosphere not been stripped away by solar wind like that of Mars?

**Tags:** planetary-atmosphere, magnetic-field, venus, solar-wind


---

## 2 answers

### Answer by username_6 on 2013-10-14. Score: 41 | Accepted answer

Venus has a strong ionosphere that protects it against violent solar winds. So, even though Venus has no intrisic magnetic field, it has an effective, induced magnetic field due to the interaction between the solar winds and the atmosphere, that protects it against solar winds.

Venus atmosphere is thick enough to have a consequent ionosphere, that would be the difference between Mars and Venus (and Venus was able to keep a thicker atmosphere due to its greater mass, contrary to Mars).

**Sources:**

* [Luhmann & Russell (1997)](http://www-ssc.igpp.ucla.edu/personnel/russell/papers/venus_mag/), on Venus
* [Luhmann & Russell (1997)](http://www-ssc.igpp.ucla.edu/personnel/russell/papers/mars_mag/), on Mars

> **Comments:**
> **username_7**: I believe I read somewhere that the character of Venus's atmosphere has been changed over the eons. Water in the atmosphere was split into separate hydrogen and oxygen atoms, with the hydrogen being blown into space by the solar winds. This makes Venus not only hot, but dry. I wonder if Earth might have benefited by capturing some of the hydrogen and matching it up with free oxygen in our atmosphere.  

---

### Answer by username_1 on 2016-09-15. Score: 8

A major factor, is that Venus' volcanoes are still active. Mars's died millions of years ago. If they were still erupting, then Mars' atmosphere would be much thicker today.

Edit: This may actually be true as referenced by a paper published July 20 2020 cited below.

Gülcher, A.J.P., Gerya, T.V., Montési, L.G.J. et al. Corona structures driven by plume–lithosphere interactions and evidence for ongoing plume activity on Venus. Nat. Geosci. (2020). <https://doi.org/10.1038/s41561-020-0606-1>

Also see in Phys.org:

* [Scientists discover volcanoes on Venus are still active](https://phys.org/news/2020-07-scientists-volcanoes-venus.html) discussed the above Nat. Geosci.
* [Scientists find evidence that Venus has active volcanoes](https://phys.org/news/2020-01-scientists-evidence-venus-volcanoes.html)

> **Comments:**
> **username_2**: Sounds about right, but can you expand this answer a little? Now it  is more of a comment.  
> **username_3**: Still, it's a pretty cool comment!  :)  
> **username_4**: Downvote: This is not known. There are indications that the surface might be young (~30 million yrs) but except for counting of large craters there is no data available on the age of the surface.  
> **username_5**: @username_4, data *is* available, in the form of changes between the [three *Magellan* mapping passes](https://en.wikipedia.org/wiki/Magellan_(spacecraft)#Orbital_encounter_of_Venus).  

---

