Looking at time lapses taken from the International Space Station, I discovered that the Earth's atmosphere can glow at night, even when it seems that those pictures were taken far away from auroras.

Here are a few examples :
enter image description here enter image description here

Here is the origin of airglow, according to this Wikipedia article:

Airglow (also called nightglow) is a faint emission of light by a planetary atmosphere. In the case of Earth's atmosphere, this optical phenomenon causes the night sky never to be completely dark, even after the effects of starlight and diffused sunlight from the far side are removed.

Now, my question is about whether or not airglow should be visible (with the naked eye) when looking at Earth's atmosphere from space at night. If not always visible or if the intensity of it varies a lot, is there a way to compute how intense it would be ?

Thank you.

  • $\begingroup$ It's probably not visible with naked eye when looking at the brightly lit side of Earth. $\endgroup$ – SF. Jun 24 '16 at 15:10
  • $\begingroup$ @SF. You mean that when you are in a completely dark area, it should be visible ? $\endgroup$ – Trevör Jun 24 '16 at 15:54
  • 1
    $\begingroup$ I mean, it's fairly dim, and when looking against the glare of Earth day side, it will be completely obscured by daylight. Same as you can't easily see stars from ISS; the glare of earthshine makes your iris to contract so much the sky is pitch black This has more to do with how human eye works, than with presence or absence of the glow. $\endgroup$ – SF. Jun 24 '16 at 16:12
  • 1
    $\begingroup$ It's a pity this will likely expire without an answer. In thinking about it, i believe the people who can really answer are on the ISS. There are opportunities regularly to ask them questions - but not this week. : / $\endgroup$ – kim holder Jul 1 '16 at 3:56
  • 1
    $\begingroup$ @kimholder Thank you for reacting to my post ! Yes, I was thinking about AMA on Reddit, do you know about other platforms where it might be possible ? $\endgroup$ – Trevör Jul 1 '16 at 6:41

The think the glow is not always visible from space. For example: the orbit of the ISS is inclined, but at least twice a year, it should be at the exact opposite side of the Earth relative to the Sun:

ang(le|el)s of light

The atmosphere stretch a bit farther out, but not a lot farther than the ISS. The light should have a hard time bending in such a drastic angle.

As for how bright it is, that must depend a lot on other condition, such as if the Sun is in the sky. Images can probably not reliably used to determine that, as a lens sees thing quite different than the eye. I guess you would have to ask a real cosmonaut for that :)

| improve this answer | |
  • $\begingroup$ I don't understand the first part of your answer, what would be the influence of the sun being at the opposite of ISS on airglow ? $\endgroup$ – Trevör Jul 2 '16 at 9:48
  • $\begingroup$ @TrevörAnneDenise Well, it is a case where it is not possible to see any airglow. So it is at least not always visible. $\endgroup$ – SE - stop firing the good guys Jul 2 '16 at 11:13
  • $\begingroup$ From what I understand, airglow doesn't require the direct presence of the sun : en.wikipedia.org/wiki/Airglow $\endgroup$ – Trevör Jul 2 '16 at 13:06
  • $\begingroup$ @TrevörAnneDenise No, but there is a limit to how far the light can be bent. That angle is simply too large. $\endgroup$ – SE - stop firing the good guys Jul 2 '16 at 14:19

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.