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Space EnvironmentHow do objects in space travel? |
Almost all of our neighbors in space are in orbit around something. All of the planets are in a circular or elliptical orbit around the Sun. Our moon and the moons of the other planets are in orbit around their planets. Comets are in an irregular orbit around the Sun. Most asteroids in our solar systems are orbiting the Sun in a band between Mars and Jupiter. Most human-made spacecraft in space are orbiting Earth. Almost all of the rest, even ones we think of as traveling to other planets, are in orbit around the Sun.
Even our Sun is traveling around the center of the Milky Way galaxy. The huge amount of matter there acts as a gravitational center for the other stars in the Milky Way. They travel around the center of the Milky Way as our planets go around the Sun.
There are a few things that we are familiar with, though, that aren't in orbits. When a meteorite enters our atmosphere and becomes a "shooting star," it is no longer in an orbit. Some space probes like Voyager have achieved escape velocity and broken away from the pull of the Sun's gravity and left the solar system. These space probes are not in orbit around a planet or the Sun, or they would stay near a planet or continue in a loop around the Sun.
What is a satellite?
How do we put a spacecraft into orbit?
What role does the Sun play in space missions like DS1's?
