(Viewed 690 times)

[Galaxy]

Hi smart people. I saw something once and an amateur astronomer tried to explain it to me. Do you agree with him? While staring at the night skies for a full minute I saw what I believed to be a satellite drifting slowly across the sky. I looked away for just a second. The thing was gone when I returned my gaze. The astonomer said it was due to the curvature of the earth. Can a satellite really disappear that quickly? what's your explanation?

[Chicago Astronomer - Astro Joe]

Why does a satellite just vanish?...

Galaxy, what you saw happens everyday, many times a day. I too have seen objects shining brightly, only to disappear in an instant overhead. The explanation provided to you is in a sense correct, but too simplified.

Here we will break it down...

Galaxy, in the great state of Idaho, with crystal clear skies stretching from horizon to horizon, she can follow all objects clearly.

• First, she spots a satellite orbiting from East to West (A), brightly reflecting the sunlight

• As the satellite continues to orbit the planet, it enters the Earth's shadow, (B), and POOF, it vanishes from sight as it is completely cloaked in darkness.

• As the object leaves the Earth's shadow and re-enters the sunlight, (C), we re-gain visible contact with the satellite and follow it to the horizon, only for it to repeat the hide and seek game in a short time, or until it re-enters the atmosphere and burns up. Then it's a different show!

The best time to view overhead satellites is just after dusk and just before dawn, as the sunlight coming from behind us illuminates
the objects "over the Earth's shoulder".

From the perspective of the satellite, the sun would be "Eclipsed" many times in it's day, with many sunsets and sunrises to behold.

I hope this answers your question about vanishing satellites.

Joe
[glow=blue,2,300]Chicago Astronomer[/glow]

[Galaxy]

Thank you Astronomer Joe for that great explanation. The drawing really helps. I do understand better now. You've got a lot of knowledge. I hope many more folks out there will ask questions too.