One of Jupiter’s largest moons. Ganymede, the largest
satellite in our solar system, is about 5300 kilometers (3300 miles) wide
and larger than the planet Mercury.
The innermost of Jupiter’s four large moons. Due to Jupiter's
gravitational might, Io is geologically active; its surface is peppered with
volcanoes that send sulfurous eruptions into its thin atmosphere. Io appears
to have the most active volcanoes in the solar system.
Io Plasma Torus
A bagel-shaped region of trapped sulfur ions around Jupiter
that originates from the surface of Io, one of Jupiter’s moons. Gravitational
tidal forces between Jupiter, other Galilean moons, and Io cause tidal friction
in Io’s interior, producing geysers that spew sulfur at tremendous speeds.
Some of the sulfur ions leave Io’s surface and become trapped around Jupiter.
A darkening of the Moon, as viewed from Earth, caused
when our planet passes between the Sun and the Moon.
A dark, flat, large region on the surface of the Moon.
The term is also applied to the less well-defined areas on Mars. Although maria
literally means “seas,” watery regions do not exist on the Moon
or Mars. Marias on the Moon may be evidence of past volcanic lava flows.
A large body orbiting a planet. On Earth’s only moon,
scientists have not detected life, water, or oxygen on this heavily cratered
body. The Moon orbits our planet in about 28 days.
The layer of loose rock resting on bedrock (sometimes
called mantle rock), found on the Earth, the Moon, or a planet. Regolith is
made up of soils, sediments, weathered rock, and hard, near-surface crusts.
On the surface of the Moon, regolith is a fine rocky layer of fragmentary debris
(or dust) produced mainly by meteoroid collisions.
A phenomenon in which the Moon’s disk passes in front
of the Sun, blocking sunlight. A total eclipse occurs when the Moon completely
obscures the Sun’s disk, leaving only the solar corona visible. A solar
eclipse can only occur during a new phase of the Moon.
The largest of Neptune’s satellites. Triton has an atmosphere
and is roughly the size of Earth's moon. It has an “ice cap” of frozen
nitrogen and methane with “ice volcanoes” that erupt liquid nitrogen,
dust, and methane compounds from beneath its frozen surface.
A break or vent in the crust of a planet or moon that
can spew extremely hot ash, scorching gases, and molten rock. The term volcano
also refers to the mountain formed by volcanic material.