September 26, 2007: Geostationary satellites
http://cellar.org/2007/nso_geosats.jpg
This was an Earth Science Pic of the Day a few days ago. This is 8 and a half hours of an open shutter pointed at the sky. Now, that makes clear what the trails are - stars, captured as they move across the sky while the earth rotates. But then, the dots that don't have any trail are geostationary satellites, in geostationary orbit. They don't have any trail because they move along with the rotation of the Earth. They orbit at exactly the equator. That means stationary dishes on Earth can "see" them at all times, which is why there are so many of them. People don't want to move their dishes! So if you follow: the camera is stationary on Earth, except that it's not stationary at all; it's moving with the rotation of the Earth. The satellites appear to be stationary in the picture, but that's only because they are moving in exact harmony with the motion of the camera. And the things that appear to move completely across the image are stars, entirely stationary. Well, except that they probably aren't -- but with our short span of attention, our 70 years, we can't sit around long enough to notice that motion... we can't perceive it. So why does XM Radio have three satellites while Sirius appears to have none? Sirius' satellites use a different type of orbit, a Tundra orbit. This allows two of their three satellites to be visible to all of North America at any given time. |
We need more Directv satellites.
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Now I know why XM radio is always playing ZZ Tops LaGrange.
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This is too complicated and 'boy' looking for me to know or care what it is. It's some kind of "graph" that employs the ugliest green color in the world so it is not worth my attention.
How come there are no GIRL-focused IotD stuff like shoes or diamond rings or self-tanning products on the Cellar? Ever ask yourself that, UT? |
Actually, Brianna, that's a close-up of the skidmarks you left when you dragged your butt across the carpet.
The labels pinpoint different things you've had for dinner recently. |
Oh! Thanks, Flint! I knew it was something you'd know about!
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Has anyone noticed several of the star tracks suddenly winked out? Is the sky falling?
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End of the Star
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Help
Where do you put suggestions for IotD?
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Send as links or attachments with all relevant info to undertoad @ cellar dot org.
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Thanks
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Damn...there are still women who play that "I'm too dumb to understand because I'm a girl..." game? I truly hope that was sarcasm...
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Where are the GPS satellites?
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