by Chris Peterson » Thu Nov 30, 2023 8:07 pm
johnnydeep wrote: ↑Thu Nov 30, 2023 7:32 pm
Chris Peterson wrote: ↑Thu Nov 30, 2023 5:04 pm
johnnydeep wrote: ↑Thu Nov 30, 2023 4:55 pm
But even if the light was right, wouldn't all the satellites be too tiny to see?
So are stars. So are satellites to our eyes on the ground. "Seeing" isn't the same as "resolving". We see point sources as long as they send enough photons our way to rise above the background noise. To see satellites in an image like this, we'd have to expose long enough to show stars. And while there would be satellites in the image (although the glare from the hugely overexposed Earth might be a problem), I don't know that we could distinguish them from stars. After all, we look up at the sky from the ground and unless they're moving, can't readily identify satellites.
Thanks. So would you say it's reasonable to think that the photons reflected Orion's way from satellites orbiting the Earth 430,000 away is within an order of magnitude of the photon flux it would receive from a Sun-like star a hundred light years away? Math would help of course, but what would you guesstimate?
Well, the Sun from 100 ly away would have an apparent magnitude of about 7. Most geosynchronous satellites I capture when imaging near the celestial equator are around mag 12, so about 100 times dimmer than that. But they can flare up to mag 5 or 6. So broadly, we could consider high orbit satellites to be similar to nearby Sun-like stars.
[quote=johnnydeep post_id=335374 time=1701372772 user_id=132061]
[quote="Chris Peterson" post_id=335367 time=1701363872 user_id=117706]
[quote=johnnydeep post_id=335365 time=1701363356 user_id=132061]
But even if the light was right, wouldn't all the satellites be too tiny to see?
[/quote]
So are stars. So are satellites to our eyes on the ground. "Seeing" isn't the same as "resolving". We see point sources as long as they send enough photons our way to rise above the background noise. To see satellites in an image like this, we'd have to expose long enough to show stars. And while there would be satellites in the image (although the glare from the hugely overexposed Earth might be a problem), I don't know that we could distinguish them from stars. After all, we look up at the sky from the ground and unless they're moving, can't readily identify satellites.
[/quote]
Thanks. So would you say it's reasonable to think that the photons reflected Orion's way from satellites orbiting the Earth 430,000 away is within an order of magnitude of the photon flux it would receive from a Sun-like star a hundred light years away? Math would help of course, but what would you guesstimate?
[/quote]
Well, the Sun from 100 ly away would have an apparent magnitude of about 7. Most geosynchronous satellites I capture when imaging near the celestial equator are around mag 12, so about 100 times dimmer than that. But they can flare up to mag 5 or 6. So broadly, we could consider high orbit satellites to be similar to nearby Sun-like stars.