- Planetary scientists use this word to refer to water, methane, and ammonia,
which usually occur as solids in the outer solar system.
- Rrock or mineral that solidified from molten or partly molten material.
- Rocks melted during impact, including small particles dispersed in
various impact deposits and ejecta, and larger pools and sheets of melt
that coalesce in low areas within the crater. Impact melts are extremely
uniform in their composition but highly variable in texture. They are
composed predominantly of the target rocks, but can contain a small but
measurable amount of the impactor.
- The inclination of a planet's orbit is
the angle between the plane of its orbit and the
The inclination of a moon's orbit is
the angle between the plane of its orbit and the plane of its
- The planets Mercury and Venus are inferior planets because their
orbits are closer to the Sun than is Earth's orbit.
interplanetary magnetic field (IMF)
- The magnetic field carried with the solar wind.
- An atom or molecular fragment that has a positive electrical charge
due to the loss of one or more electrons; the simplest ion is the
hydrogen nucleus, a single proton.
- A region of charged particles in a planet's upper atmosphere;
the part of the earth's atmosphere beginning at an altitude of about
400 kilometers (25 miles) and extending outward 400 kilometers
(250 miles) or more.