September 26, 2007: Geostationary satellites

Undertoad · 09-26-2007, 09:11 AM

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.

theotherguy · 09-26-2007, 09:43 AM

We need more Directv satellites.

barefoot serpent · 09-26-2007, 11:27 AM

Now I know why XM radio is always playing ZZ Tops LaGrange.

Trilby · 09-26-2007, 12:04 PM

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?

Flint · 09-26-2007, 12:08 PM

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.

Trilby · 09-26-2007, 12:30 PM

Oh! Thanks, Flint! I knew it was something you'd know about!

BigV · 09-26-2007, 12:45 PM

Quote:

Originally Posted by Brianna

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?

Did you just volunteer for IotD-er of the month duty? Cause we're looking for one.

spudcon · 09-26-2007, 12:52 PM

Has anyone noticed several of the star tracks suddenly winked out? Is the sky falling?

hampor · 09-26-2007, 04:19 PM

Quote:

Originally Posted by spudcon

Has anyone noticed several of the star tracks suddenly winked out? Is the sky falling?

That's just where the star happened to be when the exposure started or stopped.

BeltNah · 09-26-2007, 04:49 PM

Where do you put suggestions for IotD?

Undertoad · 09-26-2007, 05:18 PM

Send as links or attachments with all relevant info to undertoad @ cellar dot org.

BeltNah · 09-26-2007, 05:46 PM

Thanks

Sarasvati48 · 09-26-2007, 07:47 PM

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...

Trilby · 09-26-2007, 07:51 PM

Quote:

Originally Posted by Sarasvati48

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...

um...what do you mean by that?

09-26-2007, 10:09 PM

Where are the GPS satellites?

09-26-2007, 09:11 AM	#1
Undertoad Radical Centrist Join Date: Jan 2001 Location: Cottage of Prussia Posts: 31,423	September 26, 2007: Geostationary satellites 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.

09-26-2007, 11:27 AM	#3
barefoot serpent go ahead, abbrev. it Join Date: Jun 2005 Location: Lawrence, KS Posts: 2,623	Now I know why XM radio is always playing ZZ Tops LaGrange. __________________ Chooses rowing vs. wading

09-26-2007, 12:08 PM	#5
Flint Snowflake Join Date: Mar 2006 Location: Dystopia Posts: 13,136	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. __________________ **************** There's a level of facility that everyone needs to accomplish, and from there it's a matter of deciding for yourself how important ultra-facility is to your expression. ... I found, like Joseph Campbell said, if you just follow whatever gives you a little joy or excitement or awe, then you're on the right track. . . . . . . . . . . . . . . . . . . . . . . . . . . Terry Bozzio**

09-26-2007, 04:49 PM	#10
BeltNah Regulator of Squalor Join Date: Feb 2007 Location: Sydney, Australia Posts: 37	Help Where do you put suggestions for IotD?

09-26-2007, 09:43 AM	#2
theotherguy no not that other guy, the other one Join Date: May 2007 Location: TN Posts: 640	We need more Directv satellites.

09-26-2007, 12:04 PM	#4
Trilby Slattern of the Swail Join Date: Jul 2004 Posts: 15,654	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?

09-26-2007, 12:30 PM	#6
Trilby Slattern of the Swail Join Date: Jul 2004 Posts: 15,654	Oh! Thanks, Flint! I knew it was something you'd know about!

09-26-2007, 12:52 PM	#8
spudcon Beware of potatoes Join Date: May 2007 Location: Upstate NY, USA Posts: 2,078	Has anyone noticed several of the star tracks suddenly winked out? Is the sky falling?

09-26-2007, 05:18 PM	#11
Undertoad Radical Centrist Join Date: Jan 2001 Location: Cottage of Prussia Posts: 31,423	Send as links or attachments with all relevant info to undertoad @ cellar dot org.

09-26-2007, 05:46 PM	#12
BeltNah Regulator of Squalor Join Date: Feb 2007 Location: Sydney, Australia Posts: 37	Thanks

09-26-2007, 07:47 PM	#13
Sarasvati48 Mystical Miscreant Join Date: Sep 2006 Posts: 46	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...

09-26-2007, 10:09 PM	#15
aero geek Guest Posts: n/a	Where are the GPS satellites?

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