If colonists or space-tourists spend time on the Moon or on Mars long enough to have a chance to take a good look at the nighttime sky, will they be able to see stars and the Milky Way?

Will they look about the same as they do from Earth?

Let's assume that the window (or visor) they are looking through is clean and of good optical quality, and there is no other ambient light.

This question is different than the questions

Here I'm asking about the visual impression and aesthetics of the stars and the Milky Way as seen by space colonists or tourists, whereas the other questions are about positional astronomy and resolution.

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    $\begingroup$ What is like death? $\endgroup$
    – user10509
    Jul 10 '19 at 7:53
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    $\begingroup$ @Madara JanDoggen is not using sarcasm, he is asking what you mean. I don't get it either. What do you mean by "Can the night sky be seen like death"? The sentence doesn't make any sense. $\endgroup$
    – Infrisios
    Jul 10 '19 at 9:16
  • $\begingroup$ The night sky is dark on the Earth, I still do not understand your question. $\endgroup$
    – GdD
    Jul 10 '19 at 9:51
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    $\begingroup$ In areas that are no light pollution, galaxies and stars are visible in the sky. But the pictures we have taken from Mars do not show such perspectives. $\endgroup$
    – Elliot
    Jul 10 '19 at 11:51
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    $\begingroup$ @Madara I think the question is a good one, but I guess that the way it is written, it's a bit unclear to five people. The stars will be a little bit brighter on the Moon and on Mars at night, if you were there looking up, but photographs taken on those bodies don't show stars the same way that a simple snapshot at night on Earth won't show stars, the exposure time is just too short. That's all it is. A long exposure on the Moon or on Mars (at night) will show the same beautiful sky as it would on Earth, and very slightly brighter because there is less air. $\endgroup$
    – uhoh
    Jul 10 '19 at 13:08

First of all, the distances in the solar system are absolutely tiny compared to the distances between stars. To the casual observer, the celestial sphere (by which I mean everything in the sky except for the Sun and planets) will look absolutely identical to how it does on earth, or pluto for that matter.

From a specific arbitrary point on mars, the sky will behave essentially the same. Mars is very similar to earth in its rotation behaviour. It has an axial tilt of 25 degrees (compare Earth, which has a tilt of 23 degrees), and its day is only 39 minutes longer than ours, so if one were to set up a tripod and film a timelapse of the night sky at different times of year, the result would be very similar to doing the same on earth. Its north pole is pointing in almost the opposite direction to us, so when Mars is on the same side of the Sun as us, it will have the opposite season.

Mars has ~1/100th the atmosphere of earth. This means there is much less atmospheric distortion, and the stars would not appear to twinkle so much. For instance, where I live, Canopus is often just above the horizon, and appears as a twinkling blue/red star. It would not look like this on Mars. The seeing will be way better on Mars than on Earth, although still not as good as in space.

The planets will look slightly different from Mars. This wikipedia article gives a good account. The brightest objects in the sky, in order, are the Sun, Phobos, Deimos, the Earth-moon system (which can be resolved by the naked eye), followed by Venus and the rest. The Sun will appear to have a 33% smaller radius, and shadows cast by it will be correspondingly sharper.


According to @RobJeffries' answer:

Even in favourable conditions, the optical depth of the Martian atmosphere is usally somewhere between 0.5 and 1 per airmass. (Petrova et al. 2012; Lemmon et al. 2014) and is nearly wavelength independent. This corresponds to a reduction in flux to between 37% and 60% of its value above the atmosphere. This compares to a typical optical (V-band) extinction of around 0.1 magnitude at a good site on Earth, which allows 90% of the flux through. There are times when it can be much worse than this on Mars.

As a rough guide to the effect this has I took the Hipparcos catalogue and made a frequency histogram of V-magnitude of the stars. If we define a Hipparcos magnitude of 6 as the limit you can see from a good dark site on Earth, then you would see 4559 stars (that's over the whole of the sky in both hemispheres). If that limit was reduced to 5.56 or 5.04, then this number decreases to 2745 or 1560 respectively. Thus there would be a reduction in the number of stars you could see by typically between a factor of 1.66 and 2.92.

What this means is that you might see slightly more stars from the Moon due to the lack of an atmosphere, but a lot fewer stars from Mars due to the substantial dust content of Mars' atmosphere even when there haven't been any recent dust storms.

If there have been storms recently, the atmosphere will be even more dense until the dust settles.


Yes, as both the lunar and Martian night skies contain Earth.

If you mean just the stars, then yes to that too, technically. There is a very small parallax difference. Not enough to notice with the naked eye. You would need sophisticated measuring gear.

If you were just using naked eye observations, and ignored Earth, it'd be pretty hard to notice a difference. You could probably figure out that the year length is a bit different on Mars with multiple observations over time.

The positions of the other planets would appear somewhat different in the Martian sky. Venus would be further away. The motion of the planets would not correspond exactly to those as seen from Earth, but I dont think you'd be able to notice this, at least not without accurate tables predicting their motions and making comparisons over a long time.

If you are just taking casual looks with your naked eye, and ignore the presence of Earth, and ignore atmospheric effects, then you will not notice any difference to the stars and milky ways appearance.


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