<p>Mars (the planet with an axial tilt closest to that of the Earth) has an axial tilt that varies greatly over time. For instance, <a href="https://www.nature.com/articles/nature03055" rel="nofollow noreferrer">4 million years ago, the mean obliquity was <span class="math-container">$∼35 ± 10°$</span></a>. From the same article:</p>
<p><a href="https://i.sstatic.net/zx8EE.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/zx8EE.jpg" alt="enter image description here" /></a></p>
<p>Earth on the other hand has had its rotational features stabilized due to the effect of our large Moon.</p>
<p>So it is only by chance if the axial tilt of Mars is currently similar to that of Earth.</p>

CC BY-SA 4.0
2020-07-20T15:32:31.513Z
2020-07-20T15:32:31.513Z
usernumber
<p>Half of the planets in the solar system have an axial tilt of <span class="math-container">$25.5\pm 3^\circ$</span>: earth (23.5°), mars (25.3°), saturn (26.7°) and neptune (28.3°). If random collisions in the early solar system caused the axial tilt of the planets, it seems like there should be a lot more variation in the planetary tilts. Is there some mechanism that favors tilts around 25°, or is this just a statistical fluke?</p>

CC BY-SA 4.0
2020-04-19T09:47:53.197Z
Sort of related: https://astronomy.stackexchange.com/q/26561/16685 FWIW, the axial tilt of Mars is much more variable than Earth's because our large Moon stabilizes it.
PM 2Ring
<planet><solar-system><planetary-formation><obliquity>
Is there any thing special with an axial tilt of roughly 25°?
usernumber
# Is there any thing special with an axial tilt of roughly 25°?

(Asked by: username_0 on 2020-04-19)

Half of the planets in the solar system have an axial tilt of $25.5\pm 3^\circ$: earth (23.5°), mars (25.3°), saturn (26.7°) and neptune (28.3°). If random collisions in the early solar system caused the axial tilt of the planets, it seems like there should be a lot more variation in the planetary tilts. Is there some mechanism that favors tilts around 25°, or is this just a statistical fluke?

**Tags:** planet, solar-system, planetary-formation, obliquity
> **Comments:**
> **username_1**: Sort of related: https://astronomy.stackexchange.com/q/26561/16685 FWIW, the axial tilt of Mars is much more variable than Earth's because our large Moon stabilizes it.  

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## 1 answers

### Answer by username_0 on 2020-07-20. Score: 3 | Accepted answer

Mars (the planet with an axial tilt closest to that of the Earth) has an axial tilt that varies greatly over time. For instance, [4 million years ago, the mean obliquity was $∼35 ± 10°$](https://www.nature.com/articles/nature03055). From the same article:

[![enter image description here](https://i.sstatic.net/zx8EE.jpg)](https://i.sstatic.net/zx8EE.jpg)

Earth on the other hand has had its rotational features stabilized due to the effect of our large Moon.

So it is only by chance if the axial tilt of Mars is currently similar to that of Earth.


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