zlacker

To me, they look like little white dots moving across the sky. Brightness can change as they move too. It'll start off bright and then as it goes away it eventually disappears entirely. Since I usually sit in the same position in the hot tub, I've come to notice that I usually see one of them cross a pretty specific path from north to south, so I've gotten used to looking in that part of the sky as I'm sitting there. It happens so frequently, I get a little disappointed if I don't see one!

Planes are similar, but tend to have flashing or colored lights and obviously aren't as far away.

I'm in a big city, but close to the ocean so I have a bit less light pollution. The city is also heavy military, so that could be part of the frequency.

Update: if you're near any of the spacex launches, you can watch the rocket too. I'm house sitting in Irvine, CA and saw the Monday launch go right near the house. Amazing to watch the plume from the rocket!

>>latchk+(OP)
I guess they disappear as they approach the horizon because the light is spread/absorbed too much by going through more atmosphere?

>>aqfamn+Z
I actually see them disappear long before they get to the horizon. My guess is just less reflected light on whatever is shiny on the satellite.

>>aqfamn+Z
My impression was that you can only see them as they reflect sunlight in your direction. As the angle formed between you, the satellite and the sun changes, you will first not see the satellite, then see, then not see it again.

And of course, if it is 3am, and there is no sunlight at any altitude because the sun is on the other side of the world, no satellites are visible.

I could be wrong.

>>latchk+r1
that and/or entering the Earth penumbra.

>>latchk+(OP)
Just throwing this out there, but has anyone else seen 'formations' of satellites? I've only seen them once but there were about 5 to 10 (it was a while ago) of what I'm assuming are satellites moving in a line formation at high speeds across the night sky. They're too distant and too fast to be planes so I'm assuming they are some sort of military formation of satellites?

>>streb-+E4
That's often a recently launched StarLink formation -- the bunch up in a line when deployed, and have to be maneuvered over several weeks to spread out and take different orbits.

>>streb-+E4
> They're too distant

I don’t know how you would know that. People are very bad at seeing distances at these scales.

If they were indeed satelites they could be starlink satelites. They are put into orbit as a bunch together and then they spread along their orbital path as they take up their position.

This article has a picture, maybe you can check if it is similar to what you have seen? https://earthsky.org/space/spacex-starlink-satellites-explai...

If you could recall more details then maybe we can figure out more exactly what this might have been. (Such as where you were, which direction you were looking at, when did this happen, how fast did they cross the sky and how far the dots were from each other. Were the line spread in the direction they were moving or sideways?)

>>m2fkxy+Y1
In higschool we did an experiment with one of our science teachers based on this fact. We measured the duratuon of the iridum flares and could use some basic geometry to estimate how high their orbit is based on where the shadow of the earth is.

I don’t remember the details anymore, but it was one of the coolest practical experiments we did.

>>streb-+E4
I saw ISS in formation with visiting spacecraft a couple times - once with Space Shuttle back in the day and at least once with Dragon. Looks pretty interesting. :)