Glossary

at·om, noun:
The basic block of matter. All kinds of matter in the universe are made up of atoms.

bi·na·ry star sys·tem, noun:
two stars orbiting around each other

co·or·di·nates, plural noun:
a set of numbers used in specifying the location of a point on a line, on a surface, in space, or in time

explanation of dense:
If an object is dense, its atoms are packed together very tightly.

explanation of density:
Density is an object's weight divided by its size, so as size gets infinitely small, density gets infinitely large.

e·lec·tri·cal charge, noun:
the property of an object which allows it to produce and respond to electric forces (whose value can be positive, negative, or even neutral [no charge])

e·lec·trons, plural noun:
fundamental particles of matter, with a negative charge

event ho·ri·zon, noun:
the boundary of a black hole

general theory of rel·a·tiv·i·ty, noun:
Albert Einstein's laws of physics, where gravity is described as a curvature of space-time

grav·i·ta·tion·al col·lapse, noun:
the collapse of an object due to the forces of gravity

grav·i·ta·tion·al waves, plural noun:
waves of space-time curvature that travels at the speed of light

mat·ter, noun:
the material substance that occupies space, has weight, and makes up the known universe

qua·sar, noun (short for quasi-stellar object):
an compact object that appears to be a star but emits high amounts of radiation and is very far away, often at the centers of galaxies and often believed to be powered by a galactic black hole

ra·dio gal·axy, noun:
a galaxy known to emit strong radio waves

space-time, noun:
the four-dimensional "fabric" that is the result when space and time become one

space-time con·tin·u·um, noun:
another way of saying space-time

spa·tial, adjective:
having to do with space

spher·i·cal, adjective:
having the shape of a sphere (a sphere is a 3-dimensional circle, an object in the shape of a ball)

su·per·gi·ant star, noun:
a very large and very bright kind of star

tid·al forces, noun:
Gravitational forces that squeeze objects in some directions and stretch them in others, as a result of the fact that different parts of the object see the source of the gravity at slightly different directions or distances. Tidal gravity produced by the Moon is responsible for the tides on Earth's oceans. This effect takes place when you fall into a black hole. Click here to see a picture of this

x-rays, plural noun:
electromagnetic waves with a wavelength between that of ultraviolet (UV) radiation (the radiation that gives you sunburn) and gamma rays