Space Vocabulary

Sphere A round object, like a globe. In space, a planet, moon or star. Origin: 1250–1300; < LL sphēra,  L sphaera  globe < Gk sphaîra  ball; r. ME spere  < OF spere  < LL spēra,  var. of sphēra

Axis The line around which a body, or planet, rotates Origin: 1540–50; < L axis  an axletree, axle, axis.

Ellipse In space, an orbit that is not flat but an elongated circle. Origin: 1745–55; < F < L ellīpsis ellipsis; or by back formation from the pl. ellipses

Solstice The two times a year (December and June) when the Earth’s axis points most towards or away from the sun. Longest and shortest days. Origin: 1200–50; < ME < OF < L sōlstitium,  equiv. to sōl  sun + -stit-,  comb. form of stat-,  var. s. of sistere  to make stand ( see stand) + -ium -ium; see -ice)

Moon Phase The step in the journey around the Earth that the moon takes; can be seen in 8 phases with different amounts of light and dark Origin: 1805–15; (n.) back formation from phases

Waxing In science, when the moon is growing brighter from right to left. Wax “on” Origin: bef. 900; ME waxen,  OE weaxan;  c. G wachsen;  akin to waist —Synonyms 1.  extend, grow, lengthen, enlarge, dilate.

Waning In science, when the surface of the moon is growing darker from right to left. Origin: bef. 900; ME wanen  (v.), OE wanian  to lessen; c. MD, MHG wanen,  ON vana  to cause to wane, destroy

New Moon When the moon is in the phase where the side facing the Earth is completely dark, no illumination.

First Quarter The phase in the lunar cycle wherein the right half of the moon is illuminated Origin: 1250–1300; (n.) ME < AF; OF quartier  < L quartārius,  equiv. to quart ( us ) fourth + -ārius -ary; (v.) ME quarteren,  deriv. of the n.

Third quarter The phase of the moon when the left half is illuminated, opposite sides from 1st quarter

Solar eclipse When the moon blocks light from the Sun from landing on the Earth Origin: 1400–50; late ME < L sōlāris,  equiv. to sōl sun + -āris -ar1

Solar eclipse

Lunar eclipse When the Earth gets in the way of the Sun’s light and casts a shadow on the moon Origin: 1585–95; < L lūnāris  of the moon. See Luna

Lunar eclipse (last weekend)

Maria Dark spots on the surface of the moon Caused by asteroids hitting the surface hard enough that lava seeped up and filled in the surface Origin: 1680–90;  < L: sea

Equinox Twice a year (March and September) when the Earth’s axis is halfway between the two extreme points, creating 12 hours of light and 12 hours of dark equinox late 14c., from O.Fr. equinoxe , from M.L. equinoxium  "equality of night (and day)," from L. aequinoctium,  from aequus  "equal" + nox  (gen. noctis ) "night." The O.E. translation was efnniht . Related: Equinoctial

Rotation An object that moves or spins on its axis.

Revolution One body going around another body Moon revolves around Earth Earth revolves around Sun revolution late 14c., originally of celestial bodies, from O.Fr. revolution , from L.L. revolutionem  (nom. revolutio ) "a revolving," from L. revolutus , pp. of revolvere  "turn, roll back"