clepsydra - a water clock

sphere - a model created by Yu Shih to show the motion of planets

sundial - a plane with a vertical column on top to produce a shadow at an angle in order to calculate the time of day

yojan - a unit of dimensional measurement comparing to approximately 4.9 miles

Definitions of latin words found in "Mars Geography":

chasma - canyon

fossa - shallow trench

mensa - table mountain

mons - mountain

patera - depression, irregular crater

planitia - plain

tholus - dome-shaped hill

vallis - valley

Physics Words:

antiparticle - the correspondence to a particle, in order to create energy when they collide

big bang - a theoretical singularity that began the universe

big crunch - a theoretical singularity that will end the universe

black hole - a region of space-time from which nothing, not even light, can escape because gravity is so strong

cosmology - the study of the universe on a large scale

doppler effect - any change in the observed frequency of a wave that is caused by the motion of the wave source or observer

event - a point in space-time, specified by its place and time

event horizon - the boundary of a black hole general relativity - Einstein's theory based on the idea that the laws of science should be the same for all observers, no matter how they are moving (explains the force of gravity in terms of the curvature of a four dimensional space-time)

grand unified theory - a theory that unifies the three forces (electromagnetic, strong, and weak)

particle accelerator - a machine that uses electromagnets to accelerate moving charged particles in order to give them more energy

positron - the antiparticle of an electron (negative)

quantum - the indivisible unit in which waves may be emitted or absorbed

quantum mechanics - the study of the universe on a smaller scale

quark - a charged particle that feels the strong force (such as protons and neutrons)

red shift - the reddening of light from a star that is moving away from us

singularity - a point in space-time at which the space-time curvature becomes infinite

space-time - the four dimensional space whose points are events

special relativity - Einstein's theory based on the idea that the laws of science should be the same for all freely moving observers, no matter what their speed

wave/particle duality - the concept in quantum mechanics that there is no distinction between waves and particles