5 ms·

The amount is different.

by martini333 5y ago

rbanffy 5y ago
There are, on average, about 10K planes flying at any given moment.
- Ancapistani 5y ago
  I recently bought some modern night vision - a PVS-14 with a 3rd gen tube - and was astounded by how much more of the night sky I could see. There are a lot more planes flying around than you might think, that you can't easily see with the naked eye at night. There are also a lot more satellites. It's already the case where it's likely that there are more Starlink satellites visible at any given time than satellites for many people, and SpaceX is nowhere near done launching them. I'm sure they won't remain the only such service, either. I 100% support what SpaceX is doing here, but it's not really a fair comparison to directly compare air traffic with orbital traffic. For one thing, a much smaller proportion of air traffic is visible from a given location at a given time. For another, air traffic can be avoided if you are observing from somewhere not in a major air traffic corridor; Starlink satellites are effectively everywhere.
  - rbanffy 5y ago
    > that you can't easily see with the naked eye at night. There are also a lot more satellites. Satellites are only visible right after sunset and right before sunrise. If one passes overhead during the night, you won't see it.
    - Ancapistani 5y ago
      I can definitely see them at night under intensified IR. Perhaps not “all night” - I haven’t exactly done exhaustive tests - but I regularly see dots of constant brightness, moving at a consistent speed, from horizon to horizon. If I understand what you mean, though, I don’t see how it’s relevant. The article was speaking to astronomical telescopes, and my parent post in reference to high quality IR optics.
      - rbanffy 5y ago
        Astronomical telescopes have a very narrow field. A satellite in LEO would take a very short time to cross it and, if the orbit is known (as constellations are) it should be trivial to protect the sensor from being exposed to it. Even if it's not, we should be able to keep track of thousands of satellites. You may be able to see them in IR if they are radiating enough heat. This should be the case for some time after they cross into the night side and, in this case, it would interfere with IR observations or with sensors that pick up IR.

The amount is different.

rbanffy 5y ago

There are, on average, about 10K planes flying at any given moment.

Ancapistani 5y ago
I recently bought some modern night vision - a PVS-14 with a 3rd gen tube - and was astounded by how much more of the night sky I could see. There are a lot more planes flying around than you might think, that you can't easily see with the naked eye at night. There are also a lot more satellites. It's already the case where it's likely that there are more Starlink satellites visible at any given time than satellites for many people, and SpaceX is nowhere near done launching them. I'm sure they won't remain the only such service, either. I 100% support what SpaceX is doing here, but it's not really a fair comparison to directly compare air traffic with orbital traffic. For one thing, a much smaller proportion of air traffic is visible from a given location at a given time. For another, air traffic can be avoided if you are observing from somewhere not in a major air traffic corridor; Starlink satellites are effectively everywhere.
- rbanffy 5y ago
  > that you can't easily see with the naked eye at night. There are also a lot more satellites. Satellites are only visible right after sunset and right before sunrise. If one passes overhead during the night, you won't see it.
  - Ancapistani 5y ago
    I can definitely see them at night under intensified IR. Perhaps not “all night” - I haven’t exactly done exhaustive tests - but I regularly see dots of constant brightness, moving at a consistent speed, from horizon to horizon. If I understand what you mean, though, I don’t see how it’s relevant. The article was speaking to astronomical telescopes, and my parent post in reference to high quality IR optics.
    - rbanffy 5y ago
      Astronomical telescopes have a very narrow field. A satellite in LEO would take a very short time to cross it and, if the orbit is known (as constellations are) it should be trivial to protect the sensor from being exposed to it. Even if it's not, we should be able to keep track of thousands of satellites. You may be able to see them in IR if they are radiating enough heat. This should be the case for some time after they cross into the night side and, in this case, it would interfere with IR observations or with sensors that pick up IR.