| asteroid? small, rocky
body that orbits the sun. Most are located between Mars
and Jupiter in a region called an asteroid belt; also
called planetoids.
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
it occupies.
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
with mass.
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
on gravity.
meteor? mass of
rock or metal that enters Earth?s atmosphere,
usually burning up before reaching the planet?s
surface.
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
body.
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
object.
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
field.
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
of gases.
terrestrial? smallest
planets in the solar system, made primarily of rock.
ultraviolet? powerful
radiation, or energy, that has a wavelength shorter
than light.
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.
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