how many sattellites are there orbiting the Earth?

Answer 1

Man made i presume you mean.

I think at the last count there were 23. Most were in low orbit and are telecommiunications satelites.

Answer 2

There are literally thousands of them!

There are so many scientific, communications, military and other satellites built by so many different nations. Some of them have failed decades ago and are still in orbit while other's orbits have decayed enough for them to eventually re-enter the atmosphere. There's even a few Soviet era ones with small nuclear reactors on board floating around up there.

But apart from all these there are the launchers and boosters and other associated bits of the vehicles that put them there. All are categorized and their orbits are kept track of. There are web-sites that can tell you exactly when to see what fly over where you live. Try: heavens-above.com

Ground based radar can track very small objects/debris floating about which can cause a hazard to space missions. There's a lot of junk up there.

Answer 3

There have been about 4000 launches (some with multiple payloads) and my guess is that several hundred of the satellites involved are still active. Nine individual countries have launched satellites (USA, Russia, Japan, China, France, India, Israel, Australia, UK) as well as international consortia (ESA, the European Space Agency, being the most important of those). A large number of countries have enough money and could easily acquire the technology to launch satellites, but choose for economy and convenience to either have another country launch their payloads or to participate in the space projects of other nations.

For more info See link
http://imagine.gsfc.nasa.gov/docs/ask_astro/answers/980202e.html


It is interesting to observe that estimates tend to range widely. Although in the past we have provided a rough figure of 450-500, we have noticed that other estimates have gone as high as 700. Obviously, it is difficult to come up with a single definitive number, given that things change on a weekly basis. New satellites are launched, while others are decommissioned or suffer malfunctions that may render them inactive. Furthermore, information about the operational status of some satellites is not always readily available.

What not to count ?
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The first part of this exercise is to narrow down the timeframe. For example, there is little sense in counting satellites launched before 1980, because it is unlikely that any of these would have enough fuel to remain in orbit this long, or that they would have mission goals left to fulfill.

It should be said that every so often we are surprised to hear about a satellite that is being "turned off" many years after we thought it had surpassed its lifetime. This usually applies to scientific satellites. While operators of commercial communications satellites are glad to replace their old spacecraft with new and more capable ones, operators of scientific satellites tend to want to milk as much science as possible from theirs.

By eliminating all the satellites launched before 1980, you have reduced the number of spacecraft you need to consider by about 2,550. Now you only have to whittle away at the more manageable number of about 2,490. This is the approximate number of satellites that were successfully launched or did not suffer in-orbit failures during 1980-2000.

If you were to look at the satellites launched in 1980-1984—about 700—you could easily discount the roughly 555 Russian and Chinese satellites launched during that period. Most of those spacecraft were fortunate to last two or three years.

You could also discount all the Earth observation, experimental, military, and scientific satellites. Most had design lifetimes of not much more than five years. The only one in that group of which we are uncertain is the Landsat 5. We believe this imaging spacecraft, launched on March 1, 1984, was still functioning in 2000.

What you would be left with to consider for that period is about 40 commercial communications satellites. Most of those had design lifetimes of 8-10 years, so it is entirely possible that some could still be operational. There have been numerous cases of such satellites operating twice as long as expected. The Comstar 4, launched on February 21, 1981, is a good example. It was designed to operate for seven years, and we believe it may still be transmitting.

It is also possible that some of the Aniks, Satcoms, and Telstars launched 15-20 years ago could have some life left in them, although we are fairly certain that every INTELSAT launched in that period has been replaced.

The point is that you would be safe in eliminating all but about five of the satellites launched during 1980-1984. That would leave some 1,795 satellites for which to account—nearly all launched in 1985-2000.

For more info on above, visit link:
http://www.aiaa.org/aerospace/Article.cfm?issuetocid=122&ArchiveIssueID=17
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Answer 4

you can see all the non-secret ones in real time on Earth Satellite Tracker via NASA/JPL website

Answer 5

Astrologically speaking... 1.... Moon.