I'm writing a scene for a short story and wanted to describe a sunrise scene acurately.

If someone was in some sort of craft in the asteroid belt and their craft was coming out from behind an asteroid, could a passenger experience a visual like the Milky Way fading into nothing?

I've seen photos of the Milky Way from the ISS as well as pictures from probes like Galileo which show pitch black around a brightly lit asteroid.

My inference is that when on the dark side of a sufficiently large celestial body, the Milky Way would be visible, but as soon as you're in, or near, line of sight to the Sun, the light pollution acts similarly, or more intensely than, on Earth.

Is this the case? And if so, how far away from the Sun would you have to be to maintain unobstructed line of sight to the Sun but still see the Milky Way's band of stars—would you have to leave the Solar System?


1 Answer 1


Light pollution is mostly caused by diffusion from the atmosphere—humidity and dust within it. This is not to say that there is no light pollution at all elsewhere, as rock reflects light and can cause its own form of light pollution—for example, astronauts on the Moon weren’t able to see stars, because the lunar regolith (“soil”) was too bright. But this is an “eye” problem, as the iris closes down when we are in bright locations.

So, to answer your question, it depends how the sunrise would be seen: by an astronaut outside their ship, by an astronaut inside a spaceship, or by a camera?

An astronaut inside a spaceship might be able to see the Milky Way and other faint stars when their window is on the shadowed part of the ship and that there are no external elements reflecting sunlight (antennas or solar panels, for example). Then again, it depends how much light there is inside the spaceship (for the same reason that we don’t see stars too well while in a car, even in the middle of nowhere, as there are some lights in the car, for example the dashboard and instruments).

An astronaut outside a spaceship would be able to see the Milky Way and other faint stars if their helmet is in the shade (basically, the same situation as above).

However, a camera could be able to see the Milky Way even when the Sun is visible, provided its diaphragm isn’t closed down because of sun exposure. This probably rules out all modern instruments, though, which would adjust exposure time according to how much light there is and thus take the (visible) Sun into account.

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    $\begingroup$ Fantastic! Greatly appreciate your detail and particularly with those different examples given $\endgroup$
    – AustinFoss
    Nov 6, 2023 at 3:15
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    $\begingroup$ Actually, in both cases—human eyes and camera—the Sun being visible would create so bright glare that it wouldn't be possible to distinguish the Milky Way. At least at 1AU distance. For the eyes especially so, because unextincted sunlight is extremely bright so as to hurt if you look at it. Being near the asteroid belt would reduce the angular size of the Sun somewhat (by about 5× maybe), but without atmospheric extinction it would still be quite bright. $\endgroup$
    – Ruslan
    Nov 6, 2023 at 12:48
  • $\begingroup$ Have a look at svs.gsfc.nasa.gov/14265. Every image in the mosaics was taken with the spacecraft in sunlight. $\endgroup$
    – John Doty
    Nov 6, 2023 at 13:46
  • $\begingroup$ @Ruslan Not true, see my link above. With decent sun shades, cameras work fine. So would eyes, but I don't know that it's ever really been tried. $\endgroup$
    – John Doty
    Nov 6, 2023 at 19:02
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    $\begingroup$ @Ruslan Yes, that's the function of a sun shade. $\endgroup$
    – John Doty
    Nov 7, 2023 at 3:18

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