telescope
A device built to observe distant objects by making them appear closer
electromagnetic radiation
a form of energy that exhibits wavelike behavior as it travels through space
visible light
Electromagnetic radiation that can be seen with the unaided eye
wavelength
Horizontal distance between the crests or between the troughs of two adjacent waves
spectrum
BAND OF COLORS PRODUCED WHEN SUNLIGHT PASSES THROUGH A PRISM
optical telescope
a telescope that uses lenses or mirrors to collect and focus visible light
refracting telescope
A telescope that uses convex lenses to gather and focus light
convex lens
A lens that is thicker in the middle than at the edges.
reflecting telescope
A telescope that uses a curved mirror to collect and focus light
radio telescopes
Devices used to detect radio waves from objects in space
observatory
a building that contains one or more telescopes
constellations
A group of stars that forms a shape or pattern.
spectrograph
An instrument that separates light into colors and makes an image of the resulting spectrum.
apparent brightness
the brightness of a star as seen from Earth
absolute brightness
the brightness a star would have if it were at a standard distance from earth
light year
Distance light travels in one year.
parallax
An apparent shift in the position of an object when viewed from different locations
Hertzsprung-Russell diagram
a graph relating the surface temperatures and absolute brightness of stars
main sequence
a diagonal area on an H-R diagram that includes more than 90 percent of all stars
nebula
A large cloud of dust and gas in space
protostar
A contracting cloud of gas and dust; the earliest stage of a star's life
white dwarf
A small, hot, dim star that is the leftover center of an old star
supernova
A gigantic explosion in which a massive star collapses and throws its outer layers into space
neutron star
the small, dense remains of a high-mass star after a supernova
black hole
An object in space whose gravity is so strong not even light can escape.
binary stars
when only two stars are gravitationally bound together and orbit a common center of mass
eclipsing binary
A binary star system in which one star periodically blocks the light from the other.
open cluster
a star cluster that has a loose, disorganized appearance and contains no more than a few thousand stars
globular cluster
a large, round, densely-packed grouping of older stars
spiral galaxy
a galaxy with a bulge in the middle and arms that spiral outward in a pinwheel pattern
elliptical galaxy
A galaxy shaped like a round or flattened ball, generally containing only old stars
irregular galaxy
A galaxy that does not have a regular shape
quasar
An enormously bright, distant galaxy with a giant black hole at its center
universe
All of space and everything in it
scientific notation
A method of writing or displaying numbers in terms of a decimal number between 1 and 10 multiplied by a power of 10.
big bang
(cosmology) the theory that the universe originated 20 billion years ago from the cataclysmic explosion of a small mass of matter at extremely high density and temperature
Hubble's Law
proves that the universe is expanding. The farther a galaxy is, the faster it moves away from us. V = H x d
cosmic background radiation
The electromagnetic radiation left over from the big bang
solar nebula
the cloud of gas and dust that formed our solar system
planetesimals
Small planetary objects that form through the action of gravity during the birth of a solar system
dark matter
Matter that does not give off electromagnetic radiation
dark energy
A mysterious force that appears to be causing the expansion of the universe to accelerate