circular, elliptical
eccentric
Mercury's orbit is fairly eccentric.

high, low
stable
planetary
Earth

enter, go into
reach
put sth into, send sth into
complete, make
The spaceship made an orbit of the moon.

leave

in orbit
The satellite will remain in orbit for several years.

orbit around, orbit round (esp. BrE)
the moon's orbit around the earth

Orbit is used with these nouns as the subject:
earth, moon, planet, satellite, spacecraft

Orbit is used with these nouns as the object:
earth, moon, planet, sun