The moon revolves in its orbit in the same direction as the planet rotates about its axis

The point in the orbit of a planet, asteroid, or comet at which it is furthest from the sun

The point in the orbit of a planet, asteroid, or comet at which it is closest to the sun

The vast, bubble-like region of space which surrounds and is created by the Sun. In plasma physics terms, this is the cavity formed by the Sun in the surrounding interstellar medium

One half of the major axis. The major axis of an ellipse is its longest diameter

A dimensionless parameter that determines the amount by which its orbit around another body deviates from a perfect circle. A value of 0 is a circular orbit, values between 0 and 1 form an elliptic orbit, 1 is a parabolic escape orbit, and greater than 1 is a hyperbola

A plutoid or ice dwarf is a trans-Neptunian dwarf planet. As of 2009, Pluto, Eris, Haumea, and Makemake are the only objects officially recognized as plutoids

Mapping of variations in the structure and form of the land surface

These represent jet-like eruptions of volatiles, together with entrained dust or ice particles, without liquid (cryo meaning “icy cold”)

Discrete regions within the ring in which the particles that it comprises are mysteriously clustered together