Orbits in the gravitational field - if a small body (comet,planet...) is located in the gravitational field of a large mass, such as the Sun, then the next orbits are possible:
a) Ellipse - It is a closed orbit - planets and asteroids have orbits forms an ellipse.
b) circle - The circle is actually a special case of ellipse.
c) a parabola - trajectory of parabolic shape is related to the speed of release and launch of satellites from Earth.
d) hyperbola - path of rapid body that only once flew near the Sun (a distant comets). The hyperbola is an open path; body which once passes near the Sun will never return.
Earth, Mars, Venus, Mercury, these planets, as well as the other planets, orbit around the Sun. The American Heritage Dictionary defines orbit as “The path of a celestial body or an artificial satellite as it revolves around another body.” Our year corresponds to one journey or one orbit around the Sun for a travel time of 365.26 days. If viewed from above our North Pole, Earth’s orbit around the Sun is in a counterclockwise direction. While the Earth orbits the Sun it also spins about its own axis.
The Moon orbits the Earth in a counterclockwise direction if viewed from above the Earth’s North Pole. It takes the Moon about 28 days to complete a full orbit. Like the Earth the Moon also spins on its axis, and the time to complete one spin is the same as the time to complete one orbit.
