Earth, Moon, And Sun

Front 1

Atmosphere

Back 1

the gaseous envelope surrounding the earth; the air.

Front 2

axis

Back 2

the line about which a rotating body, such as the earth, turns.

Front 3

ellipse

Back 3

a plane curve such that the sums of the distances of each point in its periphery from two fixed points, the foci, are equal.

Front 4

hemisphere

Back 4

half of the terrestrial globe or celestial sphere, especially one of the halves into which the earth is divided.

Front 5

revolution

Back 5

an overthrow or repudiation and the thorough replacement of an established government or political system by the people governed.

Front 6

rotation

Back 6

the act of rotating; a turning around as on an axis.

Front 7

crater

Back 7

Also called impact crater, meteorite crater. (on the surface of the earth, moon, etc.) a bowl-shaped depression with a raised rim, formed by the impact of a meteoroid.

Front 8

lunar

Back 8

measured by the moon's revolutions.

Front 9

terrae

Back 9

A rough highland or mountainous region of the moon with a relatively high albedo.

Front 10

chromosphere

Back 10

a scarlet, gaseous envelope surrounding the sun outside the photosphere, from which enormous quantities of hydrogen and other gases are erupted.

Front 11

convection zone

Back 11

A region of turbulent plasma between a star's core and its visible photosphere at the surface, through which energy is transferred by convection. In the convection zone, hot plasma rises, cools as it nears the surface, and falls to be heated and rise again.

Front 12

corona

Back 12

a white or colored circle or set of concentric circles of light seen around a luminous body, especially around the sun or moon.

Front 13

nuclear fusion

Back 13

a reaction in which two nuclei combine to form a nucleus with the release of energy.

Front 14

photon

Back 14

a quantum of electromagnetic radiation, usually considered as an elementary particle that is its own antiparticle and that has zero rest mass and charge and a spin of one.

Front 15

photosphere

Back 15

a sphere of light or radiance.

Front 16

plasma

Back 16

the liquid part of blood or lymph, as distinguished from the suspended elements.

Front 17

radiative zone

Back 17

The layer of a star that lies just outside the core, to which radiant energy is transferred from the core in the form of photons.

Front 18

solar flare

Back 18

a brief powerful eruption of particles and intense electromagnetic radiation from the sun's surface, associated with sunspots and causing disturbances to radio communication on earth

Front 19

crescent

Back 19

a shape resembling a segment of a ring tapering to points at the ends

Front 20

gibbous

Back 20

convex at both edges, as the moon when more than half full.