What Is a Geosynchronous Satellite?
A geosynchronous satellite is a satellite with an orbital time of 24 hours, and they are stationary at the same point on earth once a day. Find out how a geostationary orbit will allow a geosynchronous satellite to stay above the same point with help from a science teacher in this free video on physical science.
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Hi, I'm Steve Jones. I'm going to tell you a little about Geosynchronous Satellites. Now the point about satellites is that these are objects, all satellites is the description of objects in orbits round other objects. So the moon is a satellite of the earth. But we have artificial satellites which are sent up in circular orbits round the earth and as you can imagine, you can't really have something in orbit round a pole. It has to be in a great circle orbit in this way. As you can see the green and the red ones are in a great circle orbit. Now the first we have to make sure of if we want to Geosynchronous is to make sure that the orbital time is 24 hours, the same time as it takes for the earth to rotate. So don't forget the earth is rotating at this time. So the earth is rotating and the satellites are going round the earth, totally independently, they're not affected by the earth 'cause the, they're above the atmosphere. So we've got satellites above the atmosphere rotating in their own independent orbit influence only by the earth's gravity. Their orbital time 24 hours means that they go around once in the same time that the earth takes to go around. Now therefore you've got two basic different times. You've got Geostationary orbit; now this can only occur in the equator; that a satellite above the equator, of course it's a jet great circle and therefore, that satellite, if it rotates once a day, then it will always be over the same point in on the earth. So that satellite will actually be always up there. And this is extremely useful of course. But there are other types of Geosynchronous orbits. For example, if you look at the point A here, this orbit means that this satellite is always visible at point A for quite a long time during the day. Obviously, right from here, right to there, for a quarter of the orbit of this satellite, it's going to be visible at A. This is Geosynchronous, that is you'll be able to look onto it, but at the same time each day, it is going to be there. Now by having a combination of different satellites, you can ensure that there is always one satellite in a series to log onto at any one time. It won't be much good having a TV channel where, okay, only between seven and eight in the evening could you get the satellite to work. You want a satellite working overtime and therefore, there is a set of satellites together which provide you with this service. So Geosynchronous Satellites are ones with an orbital time of 24 hours and are stationary at the same part or at the same point on the earth, once a day unless they are a Geostationary orbit, which means that around the equator, in which case then, they can be above the same point at all times. So that describes a Geosynchronous Satellite.