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uk.tech.digital-tv (Digital TV - General) (uk.tech.digital-tv) Discussion of all matters technical in origin related to the reception of digital television transmissions, be they via satellite, terrestrial or cable. Advertising is forbidden, with no exceptions.

Night photo's of geostationary satellites.



 
 
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  #11  
Old October 8th 15, 09:23 PM posted to uk.tech.digital-tv
Tim+[_4_]
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Posts: 191
Default Night photo's of geostationary satellites.

Michael Chare wrote:
On 06/10/2015 20:34, wrote:
Found this picture some of you might like:

http://imgur.com/gallery/hky2HYp

via
https://www.reddit.com/r/space/comme...ographed_last/

Then in the comments section one contributor managed to highlight the satellites:

http://i.imgur.com/TCGQX4l.gif

Rather impressive, I think!


How to the satellites below the Clarke belt stay there?


Long tethers to ones above the belt.

Tim

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  #12  
Old October 9th 15, 01:56 AM posted to uk.tech.digital-tv
Bill Wright[_2_]
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Posts: 9,381
Default Night photo's of geostationary satellites.

Michael Chare wrote:
On 06/10/2015 20:34, wrote:
Found this picture some of you might like:

http://imgur.com/gallery/hky2HYp

via
https://www.reddit.com/r/space/comme...ographed_last/


Then in the comments section one contributor managed to highlight the
satellites:

http://i.imgur.com/TCGQX4l.gif

Rather impressive, I think!


How to the satellites below the Clarke belt stay there?


It is possible to orbit once every 24 hours but not over the equator.
The satellite would not be stationary relative to the earth though.

Bill
  #13  
Old October 9th 15, 12:05 PM posted to uk.tech.digital-tv
Ian Jackson[_2_]
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Posts: 2,968
Default Night photo's of geostationary satellites.

In message , Chris Hogg
writes
On Fri, 09 Oct 2015 11:11:14 +0100, Bob Latham
wrote:

In article ,
Martin wrote:

The answer is by going round fast enough for the centrigugal/centripetal
force to balance out the force due to gravity.


I was taught that there is no such force as centrifugal force at all.


All pedants know that (I include myself!). Unfortunately the term
'centrifugal force' has become accepted parlance in vox pop.

All that remains is to decide how to pronounce it.
--
Ian
  #14  
Old October 9th 15, 01:33 PM posted to uk.tech.digital-tv
Roderick Stewart[_3_]
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Posts: 2,246
Default Night photo's of geostationary satellites.

On Fri, 09 Oct 2015 13:47:00 +0200, Martin wrote:

I was taught that there is no such force as centrifugal force at all.
It is in fact just a object trying to obey Newton's first law.

"A body will remain in a state of rest or uniform motion in a straight
line unless acted upon by a force."

The orbiting body is trying to fly off in a straight line but is
prevented from doing so by gravity. There is no outward force at all.


http://www.millersville.edu/~jdooley...EF/TORQDEF.HTM


Are you arguing or agreeing?


https://en.wikipedia.org/wiki/Centripetal_force

Centripetal force exists centrifugal is a misnomer.


Isn't the centrifugal force a reaction? "For every force there's an
equal and opposite reactive force" and all that.

Rod.
  #15  
Old October 9th 15, 01:33 PM posted to uk.tech.digital-tv
Indy Jess John
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Posts: 1,307
Default Night photo's of geostationary satellites.

On 09/10/2015 12:32, Chris Hogg wrote:
On Fri, 09 Oct 2015 11:11:14 +0100, Bob Latham
wrote:

In ,
wrote:

The answer is by going round fast enough for the centrigugal/centripetal
force to balance out the force due to gravity.


I was taught that there is no such force as centrifugal force at all.


All pedants know that (I include myself!). Unfortunately the term
'centrifugal force' has become accepted parlance in vox pop.

There is a device called a centrifuge.
Is there a device called a centripete?

Jim

  #16  
Old October 9th 15, 06:47 PM posted to uk.tech.digital-tv
Michael Chare
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Posts: 856
Default Night photo's of geostationary satellites.

On 09/10/2015 09:46, Chris Hogg wrote:
On Thu, 08 Oct 2015 20:51:56 +0100, Michael Chare
wrote:

On 06/10/2015 20:34, wrote:
Found this picture some of you might like:

http://imgur.com/gallery/hky2HYp

via https://www.reddit.com/r/space/comme...ographed_last/

Then in the comments section one contributor managed to highlight the satellites:

http://i.imgur.com/TCGQX4l.gif

Rather impressive, I think!


How to the satellites below the Clarke belt stay there?


https://en.wikipedia.org/wiki/Geostationary_orbit

Thank you for the link, but it does say:
"Orbital stability

A geostationary orbit can only be achieved at an altitude very close to
35,786 km (22,236 mi), and directly above the Equator. This equates to
an orbital velocity of 3.07 km/s (1.91 mi/s) or an orbital period of
1,436 minutes, which equates to almost exactly one sidereal day or
23.934461223 hours. This ensures that the satellite will match the
Earth's rotational period and has a stationary footprint on the ground.
All geostationary satellites have to be located on this ring."

Maybe the answer is that they don't stay still as viewed from the earth.



--
Michael Chare
  #17  
Old October 9th 15, 08:03 PM posted to uk.tech.digital-tv
Richard Tobin
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Posts: 1,383
Default Night photo's of geostationary satellites.

In article ,
Indy Jess John wrote:

There is a device called a centrifuge.
Is there a device called a centripete?


It's the same thing. A centrifuge moves heavier things outward, and
lighter things inward.

-- Richard
  #18  
Old October 9th 15, 08:15 PM posted to uk.tech.digital-tv
Richard Tobin
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Posts: 1,383
Default Night photo's of geostationary satellites.

In article ,
Chris Hogg wrote:
What satellites did you have in mind?


I assume he meant the ones in the time-lapse image which are not
moving rapidly relative to the earth but are not on the line of the
others.

There are five, of which three are clearly moving somewhat, while the
other two seem to be almost stationary.

The image, for reference: http://i.imgur.com/TCGQX4l.gif

-- Richard
  #19  
Old October 9th 15, 10:40 PM posted to uk.tech.digital-tv
Michael Chare
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Posts: 856
Default Night photo's of geostationary satellites.

On 09/10/2015 21:15, Richard Tobin wrote:
In article ,
Chris Hogg wrote:
What satellites did you have in mind?


I assume he meant the ones in the time-lapse image which are not
moving rapidly relative to the earth but are not on the line of the
others.

There are five, of which three are clearly moving somewhat, while the
other two seem to be almost stationary.

The image, for reference: http://i.imgur.com/TCGQX4l.gif

-- Richard

Indeed I did. I think these satellites are in an inclined orbit so they
will move up and down. It appears that not having satellites perfectly
positioned can be done to save fuel.

--
Michael Chare
  #20  
Old October 9th 15, 11:03 PM posted to uk.tech.digital-tv
Bill Wright[_2_]
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Posts: 9,381
Default Night photo's of geostationary satellites.

Chris Hogg wrote:

Other satellites, at altitudes between the Hubble and the Clarke belt
such as the Galileo satellites, orbit the earth at about 14,430 miles,
at a speed of about 8,200MPH and an orbital period of just over 14
hours. They are not geostationary either.


There's a satellite that orbits at about 363,000 km.It takes almost a
month to go round once.

Bill
 




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