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A Family of Planets, Ch. 20

STUDY
PLAY
waning
The sunlit part of the moon is getting smaller
waxing
the sunlit part of the moon is getting larger
Charon
Pluto's only moon
Inner Planets
Mercury, Venus, Earth, Mars: four planets closest to sun
Outer Planets
Jupiter, Saturn, Uranus, Neptune, Pluto
Mercury
A terrestrial planet; closest to the Sun
Venus
similar to earth in size and mass
Venus
the sun rises in the west and sets in the east
Earth
the sun rises in the east and sets in the west
Earth
the only planet we know of that supports life
Mars
the red planet
Saturn
the second largest planet in the solar system
Jupiter
a giant among giants; made primarily of hydrogen and helium
Uranus
the planet that is tilted on its side
Neptune
the blue world
Pluto
The furthest planet from the sun
Pluto
the smallest planet
Mercury
its year is only 88 Earth days long
Annular
eclipse a solar eclipse during which the outer ring of the sun can be seen around the moon
Asteroid
a small, rocky body that revolves around the sun
Asteroid belt
the region of the solar system most asteroids occupy; roughly between the orbits of Mars and Jupiter
Astronomical unit (AU)
the average distance between the Earth and the sun, or approximately 150,000,000 km
Comet
a small body of ice, rock, and cosmic dust loosely packed together that gives off gas and dust in the form of a tail as it passes close to the sun
Eclipse
an event in which the shadow of one celestial body falls on another
Gas giants
the large, gaseous planets of the outer solar system
Greenhouse Effect
the natural heating process of a planet, such as the Earth, by which gases in the atmosphere trap heat
Kuiper Belt
the region of the solar system outside the orbit of Neptune that is occupied by small, icy, cometlike bodies
Light-minute
a unit of length equal to the distance light travels in space in 1 minute, or 18,000,000 km
Lunar eclipse
an event in which the shadow of the Earth falls on the moon
Meteor
a streak of light caused when a meteoroid or comet dust burns up in the Earth's atmosphere before it reaches the ground
Meteorite
"a meteoroid that reaches the Earth's surface without burning up completely"
Meteoroid
a very small, rocky body that revolves around the sun
Moon
a natural satellite of a planet
Oort cloud
"a spherical region of space that surrounds the solar system in which distant comets revolve around the sun"
Period of revolution
the time it takes for one body to make one complete orbit, or revolution, around another body in space
Period of rotation
the time it takes for an object to rotate once
Phases
"the different appearances of the moon due to varying amounts of sunlight on the side of the moon that faces the Earth; results from the changing relative positions of the moon, Earth, and the sun"
Prograde rotation
the counterclockwise spin of a planet or moon as seen from above the planet's north pole
Retrograde orbit
the clockwise revolution of a satellite around a planet as seen from above the north pole of the planet
Retrograde rotation
the clockwise spin of a planet or moon as seen from above the planet's or moon's north pole
Revolution
the elliptical motion of a body as it orbits another body in space
Rotation
the spinning motion of a body on its axis
Satellite
a natural or artificial body that revolves around a planet
Solar eclipse
an event in which the shadow of the moon falls on the Earth's surface
Surface gravity
the percentage of your Earth weight you would experience on another planet; the weight you would experience on another planet
Terrestrial planets
the small, dense, rocky planets of the inner solar sys
Mercury
which planet has no moons
Venus
which planet has no moons
Luna
the Earth's moon is called
Mars
this planet has two moons
Jupiter
this planet has twenty-eight known moons
Saturn
this planet has thirty known moons
Uranus
this planet has twenty-one moons
Neptune
this planet has eight moons
Ions
Electrically charged particles
nucleus
the solid center of a comet
ellipses
circles that are somewhat stretched out of shape
meteor showers
occur when earth passes through dusty debris left behind in the orbit of a comet
stony
this is one of the three major types of meteorites
metallic
this is one of the three major types of meteorites
stony-iron
this is one of the three major types of meteorites
Io
the most volcanically active body in the solar system
Ganymede
the largest moon of Jupiter
Titan
scientists hope to answer questions about how life began on earth by studying this satellite
inner planets
small, dense and rocky