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1. The satellite needs to be passing overhead at an angle where you can see it, and clear skies etc. 2. The sky needs to be dark enough to see it (so twilight
by HPsquared 3y ago
1. The satellite needs to be passing overhead at an angle where you can see it, and clear skies etc.
2. The sky needs to be dark enough to see it (so twilight or night)
3. The satellite needs to be illuminated by the sun.
4. The satellite needs to reflect enough light that you can see it.
Basically this happens just before sunrise, and just after sunset. So the ground and sky are dark (allowing you to see through the atmosphere), and the satellite - being at high altitude - is still illuminated.
As they pass overhead, you can often see them suddenly vanish as they pass into the Earth's shadow.
The International Space Station is a good one to find, as it's quite bright (very large).
There are various websites and apps; some phone apps use the GPS and magnetometer to show you what direction and time to look, and a search tool to look for visible objects at your location. It used to be really good with the old Iridium satellites, which gave a bright flash due to their large flat antennas.
- WanderPanda 3y agoI remember chasing one of the iridium flares and it was very bright, even during the day
- carlosjobim 3y agoIn short: after sunset.
- wolverine876 3y 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.
- burnished 3y agoThat doesn't seem right, why would they be bright?
- steve_adams_86 3y agoThey reflect sunlight for some period of the evening and morning, before the sun is shining where you are and illluminating the sky too much.
- KeplerBoy 3y agoso not in the middle of the night.
- wolverine876 3y agoBetween 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-twilight.html 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!).
- jfoutz 3y agoI 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.
- HPsquared 3y agoI 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.
- wolverine876 3y ago> 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.