15-10-2015, 03:13 PM
I stumbled across this in a usenet group and hope you find it as interesting as I did.
We all know that geostationary satellites, on which we rely for, amongst other things, satellite television, are in orbit in the Clarke belt above the equator at exactly the right height to give them an orbital time of 24 hours which, provided the satellites travel in the same direction as the earth rotates, makes them appear stationary from the ground.
But, if you look up into the night sky, how do you tell a satellite apart from a star?
Somebody decided to find out and took a sequence of time lapse photographs over a four minute period at a time when the satellites were most likely to reflect the sun. Here is the result, viewed as a continuous loop (click to see image if necessary):
![[Image: hky2HYp.gifv]](http://i.imgur.com/hky2HYp.gifv)
The moving traces are the stars but, if you look carefully, you will see a line of stationary dots - the satellites - in a line running from about halfway down the right hand up to about three-quarters of the way up the left hand side. It takes a bit of patience but they are there!
However, there is a better way. Someone has taken the original sequence and modified it to highlight the satellites.
This also shows a coule of objects jumping up and down - high flying aircraft, perhaps? - and three satellites which have wandered off course into an inclined orbit.
These may be defunct craft or functional craft which have simply tun out of fuel for course correction yet might still be used for specialised services using tracking dishes á là Telstar ...
![[Image: TCGQX4l.gif]](http://i.imgur.com/TCGQX4l.gif)
We all know that geostationary satellites, on which we rely for, amongst other things, satellite television, are in orbit in the Clarke belt above the equator at exactly the right height to give them an orbital time of 24 hours which, provided the satellites travel in the same direction as the earth rotates, makes them appear stationary from the ground.
But, if you look up into the night sky, how do you tell a satellite apart from a star?
Somebody decided to find out and took a sequence of time lapse photographs over a four minute period at a time when the satellites were most likely to reflect the sun. Here is the result, viewed as a continuous loop (click to see image if necessary):
The moving traces are the stars but, if you look carefully, you will see a line of stationary dots - the satellites - in a line running from about halfway down the right hand up to about three-quarters of the way up the left hand side. It takes a bit of patience but they are there!
However, there is a better way. Someone has taken the original sequence and modified it to highlight the satellites.
This also shows a coule of objects jumping up and down - high flying aircraft, perhaps? - and three satellites which have wandered off course into an inclined orbit.
These may be defunct craft or functional craft which have simply tun out of fuel for course correction yet might still be used for specialised services using tracking dishes á là Telstar ...
