A	argon- a colorless, odorless gaseous element that can be found in volcanic gases. atmosphere- the mass of air, clouds, gases, and vapor, surrounding the Earth or other heavenly body. axis- an imaginary line about which a rotating body turns (plural axes)
B	basalt- dark colored lava rock
C	carbon dioxide - a heavy gas with no odor, formed from carbon and oxygen crater - a large hole in the ground, shaped like a bowl, that is mainly created by meteors.
D	deposit - a natural accumulation density- the amount of something per unit
E	elliptical - an oblique circle
F
G	gravitational field - the area of interaction between two masses gravity - a mutual physical force attracting two bodies.
H	hemisphere - half of a sphere
I	image- a picture formed when light shines in a mirror or through a camera lens.
J
K
L	lunar- pertaining to the moon
M	magnetic field - a region of space near a magnetized body where magnetic forces can be detected. mission- the sending forth of a person or group to perform a special job.
N	NASA - National Aeronautics and Space Administration nitrogen- a gas that has no color, smell, or taste and makes up about 70% of Earth's atmosphere.
O	Olympus Mons- the tallest volcano on Mars and in the solar system. orbit- a curved path described by a planet, satellite, etc., about a celestial body as the sun oxygen- a colorless, odorless gas that living things need to breathe. ozone layer - a layer of ozone that shields the earth from the sun's ultraviolet light
P	Pavonis Mons- a giant shield volcano on Mars that is over 12 miles high.
Q
R	radiation- light or energy such as from the sun that travels through the air.
S	satellite- a heavenly body that revolves around a planet or another large body in space. season- one of the four parts of the year like spring, summer, winter, and fall. silicon - non-metallic element found in minerals and rocks that make up 1/4 of the earth's crust. sol- the Martian day measured from noon to noon; equals 24 hours and 39 minutes. solar system- the sun and the bodies that move in orbit around it. solar wind- the charged particles (plasma), primarily protons and electrons, that are emitted from the sun and stream outward throughout the solar system at speeds of hundreds of kilometers per second. spacecraft- a vehicle capable of traveling in outer space. sphere- a round body whose surface is at all points the same distance from the center.
T	terrain- ground or land. topography- the detailed description of the physical features of an area.
U	ultraviolet radiation -invisible form of light produced by the sun that can cause health problems to living things when they are overexposed to this rays
V	Valles Marineris- an extensive and very deep canyon system on Mars volcano- a mountain with vents through which molten lava, ash, cinders and gas erupt.
W	water vapor- the gas produced when water evaporates.
X	xenon - heavy, colorless, relatively inert gaseous element
Y
Z

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