Orbits
There are three main 'bands' of orbit around the Earth: low Earth orbit (LEO), medium Earth orbit (MEO) and geostationary orbit (GEO).
Due to Orbital mechanics orbits are in a particular, largely fixed plane around the Earth, which coincides with the center of the Earth, and may be tilted with respect to the equator. The Earth rotates about its axis within this orbit, and the relative motion of the spacecraft and the movement of the Earths surface determines the position that the spacecraft appears in the sky from the ground, and which parts of the Earth are visible from the spacecraft.
By dropping a vertical down to the Earth's surface it is possible to calculate a ground track which shows which part of the Earth a spacecraft is immediately above, and this is useful for helping to visualise the orbit.
NASA provides real-time tracking of the over 500 artificial satellites maintained in orbit around Earth. For the position of these satellites see NASA satellite tracking.
Read more about this topic: Orbital Spaceflight
Famous quotes containing the word orbits:
“To me, however, the question of the times resolved itself into a practical question of the conduct of life. How shall I live? We are incompetent to solve the times. Our geometry cannot span the huge orbits of the prevailing ideas, behold their return, and reconcile their opposition. We can only obey our own polarity.”
—Ralph Waldo Emerson (1803–1882)