ISS and Satellites at night time - not twilight

[kirkster501]

Hi, anyone see satellites in the dead of night, like midnight? They are best twilight I know when there is still some sun up there to catch them. Sometimes I see the odd satellite long after the sun set but anyone see the ISS like this?

Why can we see satellites at all when its long past sunset? Light from cities and the ground reflecting off them?

Steve

[Steve Ward]

The ISS orbits about 225 miles up , it's going to be lit by the sun pretty much continuously , we see it lit by sunlight at midnight due to its "distant horizon" for want of a better phrase.

The sun sets later if you're atop a mountain than if you're in the valley so's to speak.

Hence the enormous array of solar panels . . .

[LukeSkywatcher]

The ISS orbits about 225 miles up , it's going to be lit by the sun pretty much continuously , we see it lit by sunlight at midnight due to its "distant horizon" for want of a better phrase.

The sun sets later if you're atop a mountain than if you're in the valley so's to speak.

Hence the enormous array of solar panels . . .

Exactly. Because satellites and the ISS orbit at such a distance above the earth, they will always catch sunlight...........which makes them visible to us here on the ground.

[kirkster501]

Not sure I follow guys. If the Satellite is high above the observer and the time is late - i.e. 11 through to 3 say (depending on time of year of course) how can it catch the sun? It's in the shadow of the Earth then?

[Vince1963]

Hi Kirkster, I think we only see the once which are reflecting sun light

[Urgentemente]

Pretty sure I saw a couple pass overhead when I was lying down on a sunlounger an hour or two ago waiting for some Lyrids to appear (0% success so far!).

About 2 years ago when I was doing similar one much colder winters evening, I remember looking and thinking "that faint star is moving..." (you know, when you've been out for ages and you wonder if your eyes are playing tricks..), had to go back inside and check on Stellarium to see what it had been!

[northwalesparry]

If you have stellarium you can add sats. to it . One passed in my EP last night when I was looking at panstarrs. Very cool

[ronin]

They fade when they enter th earths shadow, that is not nesessarily the same as night time/midnight. Simply you are out of line of sight of the sun but it may not be.

Think about the moon, that is far enough away that it is always visible even if it does fall into the earths shadow - it is never fully blocked off.

It is a case of umbre and penumbra, if you get a bright one it may well start out bright, fade to an orange colour then disappear. That is it being in full sun light, the penumbra then the umbra.

You will read of people swearing they must have seen a ufo as whatever it was had been bright then disappeared. Seems to often be a case of:

Being night why can I see it at all, or, it was bright why doesn't it stay bright.

[starman1969]

I was at a star party last week and we must have spotted at least 10 confirmed satellites. This was between 2300 and 01.00am.

They usually disappear soon after reaching their highest point, but there were a few which seemed to go on and on.

[Steve Ward]

There's an enormous range of satellite orbit heights ,the ISS is at about 225 miles whereas some High Earth Orbiters are at 22,000 miles.

http://en.wikipedia.org/wiki/Satellite#Orbit_types

The latter rarely fall into the Earths shadow and are therefore often visible from horizon to horizon without a break.