G - H
the letter that (probably) leads off the word in question. Please
suggest new words or corrections.
Abbr. See "gamma ray burst".
A system of billions of stars, gas and dust that has coalesced
to form a huge body. Ex. The Milky Way galaxy.
ray burst: An
intense, concentrated burst of gamma radiation whose origin
is not yet understood.
A large rocky moon orbiting Jupiter that was discovered in 1610
cluster: Gravitationally bound concentrations of approximately
ten thousand to one million stars, spread over a volume of several
tens to about 200 light years in diameter. Also see "star cluster"
and "open cluster". Ex. M13 - the Great Hercules Globular Cluster.
The attracting force that exists between two or more objects.
Every object with mass has gravity, even though its effects
can be minimal and undetectable.
See "Universal Coordinated Time"
inert, monoatomic, gaseous element occurring in the atmosphere
of the sun and stars, and in small quantities in the earth's
atmosphere. Helium is by-product of the thermonuclear fusion
of hydrogen occuring in the Sun.
colorless, highly flammable gaseous element, the lightest of
all gases and the most abundant element in the universe. The
thermonuclear fusion of hydrogen to helium in the Sun produces
its heat and energy.
of Jupiter's four large moons discovered by Galileo in 1610.
Io is one of the only known sources of active volcanism in the
condition in which an atom has acquired a net electric charge
by gaining or losing one or more electrons.
formation of ions by heat, electrical discharge, radiation,