|asteroid — small, rocky
body that orbits the sun. Most are located between Mars
and Jupiter in a region called an asteroid belt; also
astronomy — study
of celestial bodies, what they are made of and their
magnitudes and motions.
atmosphere — the
gases that surround a planet or moon, held in place
by the force of gravity.
axis — imaginary
line through poles of a planet, about which it rotates.
comet — body of ice
and dust in orbit around the sun that develops a tail
of ions and dust as it approaches the sun.
corona — sun?s
outer part, visible as a halo during a total solar eclipse
around the edge of the moon.
crater — bowl-shaped
hole on a surface made by a volcanic explosion or the
impact of a body such as a meteoroid.
density — measure
of an object?s mass in relation to how much space
eclipse — effect
caused by one body casting a shadow on another. A solar
eclipse occurs when the moon passes between the sun
and Earth, casting a shadow on Earth. A lunar eclipse
occurs when Earth passes between the sun and the moon,
casting a shadow on the moon.
gas giants — largest
four planets in the solar system (Jupiter, Saturn, Uranus,
and Neptune) made largely of dense gaseous atmosphere.
geocentric — discredited
theory that Earth is the center of the solar system.
gibbous phase — when
a moon or planet shows more than half, but not all,
of its face.
gravity — seeming
force of attraction felt between two or more objects
heliocentric — theory
that the sun is in the center of the solar system.
infrared — invisible
part of light, with longer wavelengths that are felt
as heat radiation.
light-year — distance
light travels in a vacuum in one year, approximately
5.88 trillion miles
magnetosphere — magnetic
field of a planet.
mass — measure of
the amount of matter an object contains, not dependent
meteor — mass of
rock or metal that enters Earth?s atmosphere,
usually burning up before reaching the planet?s
meteorite — mass
of rock or metal that has survived friction of Earth?s
atmosphere to reach the surface.
meteoroid — dust
and debris that travel through space and become meteors
when they enter Earth?s atmosphere.
meteor shower — large
number of meteors burning upon entering Earth?s
atmosphere, occurring when Earth?s orbit passes
through debris from a comet.
moon — natural satellite
of a planet.
nebula — cluster
of stars, or a cloud of dust particles and gases.
orbit — path followed
by a star, planet, or satellite around a more massive
penumbra — outer
and lighter part of the shadow created by an eclipse.
phase — size of the
illuminated portion of a planet or moon.
pole — end of an
axis, or the point where an axis meets the surface of
a planet (geographic); either end of a magnet and points
where the magnetic forces originate (magnetic).
planet — low-mass
body that orbits a star.
rotation — turning
around a center or an axis, or to turn in a circle.
satellite — small
object, natural or artificial, that orbits a larger
solar flare — explosion
on the sun?s surface causing a flaming arch millions
of miles long, due to a shift in the sun?s magnetic
solar system — planets
and bodies that orbit the sun and any group comprising
a central star and orbiting planets.
solar wind — stream
of charged particles emitted from the sun.
sunspot — darker
and slightly cooler region on the surface of the sun,
created when powerful magnetic fields stop the circulation
terrestrial — smallest
planets in the solar system, made primarily of rock.
ultraviolet — powerful
radiation, or energy, that has a wavelength shorter
umbra — dark central
zone created by an eclipse.
volume — amount of
space an object occupies.
wane — decrease in
the phase of a moon or planet.
wax — increase in
the phase of a moon or planet.