Comment by wolverine876
1 year ago
> Basically this happens just before sunrise, and just after sunset.
I've seen plenty of satellites in the middle of the night, from very dark areas (wilderness). They look like stars, only they move more quickly. These observations go back a decade, at least.
I was mostly referring to the brightest things like the ISS, Starlink and (formerly) Iridium satellites, which are in low Earth orbit.
Higher orbits are visible for longer, due to the angles involved: because they're so high, such satellites can remain illuminated with the Sun further below the horizon. The Moon is the most extreme example: it's almost never in Earth's shadow.
> because they're so high, such satellites can remain illuminated with the Sun further below the horizon. The Moon is the most extreme example: it's almost never in Earth's shadow.
Very good point.
That doesn't seem right, why would they be bright?
That's a very good question. I'm sure of what I've seen, many times over years:
I can tell you that they look like stars - so much that I need a reference point, an actual star or planet, to verify they are moving and not a 'stationary' star (judging movement being otherwise very difficult at that distance). They move very steadily, horizon to horizon, or as far as I can track them. A wild guess, based on memory, is one might take 5 or 10 minutes to cross between my horizons (usually I'm not on a plain - trees, hills, mountains may elevate my 'horizons' and reduce the distance).
Natural celestial object? No way a star is moving that fast relative to other stars and Earth's horizons. Asteroid? That seems hard to believe, due to size and illumination. Comet? Are there lots of tiny ones? I never see tails. Maybe a meteorite entering the atmosphere that doesn't yet have a tail?
Other human-made objects? Airplanes would look bigger and have colored, blinking lights - I've seen plenty of airplanes at night. Maybe there are higher flying airplanes without the colored and blinking lights? Are they illuminated whitish, and so far away they'd look like stars?
I've seen them so many times, I'm confident that I could take anyone to a wilderness area on a clear night and find one within 15-20 minutes, probably less.
> A wild guess, based on memory, is one might take 5 or 10 minutes to cross between my horizons (usually I'm not on a plain - trees, hills, mountains may elevate my 'horizons' and reduce the distance).
Yup 5-10 minutes is right. It depends on the orbit altitude and the height of the pass.
You can use sat tracker apps to identify which one you're seeing. I do this sometimes because I'm a ham radio operator and I track the one I want to use sometimes with a directional antenna.
> No way a star is moving that fast relative to other stars
No star moves relative to other stars when viewed from earth. They are all so far away they appear static. The starscape rotates as a whole (well it doesn't, the earth does, but to the observer it seems that way), but relative to each other they absolutely don't move.
If they do move, it is definitely a sign to stop drinking :) :)
> Asteroid? That seems hard to believe, due to size and illumination.
Also asteroids move way faster across the sky than a satellite. And they're rare except during that time of the year when they're really common.
> Comet? Are there lots of tiny ones? I never see tails.
Comets are incredibly rare in this galactic neighbourhood.
> and Earth's horizons. Asteroid? That seems hard to believe, due to size and illumination. Comet? Are there lots of tiny ones? I never see tails.
> Asteroid? That seems hard to believe, due to size and illumination.
And the distance - most asteroids pass by much further out than even the moon, so their motion would be hard to detect.
I grew up in a rural area, on a moonless night, without a fire, as well as giving your vision some time to adjust to the darkness, you can see crazy amounts of stars along the Milky Way plane.
I would guess, reflected moonlight (moon over the horizon) would be enough to light up the dot well enough to see unaided.
They reflect sunlight for some period of the evening and morning, before the sun is shining where you are and illluminating the sky too much.
Between when the sun first disappears below the horizon and when (nearly) all its light disappears, i.e., the end of astronomical twilight when the Sun's center is 18 deg below the horizon, seems to be about 90 minutes.
https://www.timeanddate.com/astronomy/different-types-twilig...
It's been awhile, but I'm pretty sure I've seen these much later than that. I'm talking about lying in a sleeping bag, looking up at the amazing starfields of pitch-black wilderness nights (tip: never use a tent except in extremis - look what you're missing!).
so not in the middle of the night.
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