The orbits of planets around the Sun, or of satellites around the Earth, can be ________
A
Circular and elliptic
B
Circular and hyperbolic
C
Elliptic and parabolic
D
Parabolic and hyperbolic
Correct Answer: Circular and elliptic
All the planets are satellites around the Sun. Almost every ship launched from Earth can be considered a satellite, as it is orbiting either the Earth or the Sun. Even though a space probe is going "out" from the Earth to Jupiter, it is still in orbit around the Sun, so it is still a satellite. It is certainly possible to set up a satellite so that it has a circular orbit (a circle is just an ellipse whose foci coincide). Gravity can only pull in the direction toward the planet.