Science Astronomy Chapter 15 Vocab

Front 1

electromagnetic radiation

Back 1

energy that can travel through space in the form of waves.

Front 2

visible light

Back 2

electromagnetic radiation that can be seen with the unaided eye.

Front 3

wavelength

Back 3

the distance between the crest of one wave and the crest of the next wave.

Front 4

spectrum

Back 4

the range of wavelengths of electromagnetic waves.

Front 5

optical telescope

Back 5

a telescope that uses lenses or mirrors to collect and focus visible light.

Front 6

refracting telescope

Back 6

a telescope that uses convex lenses to gather and focus light.

Front 7

convex lens

Back 7

a piece of transparent glass curved so that the middle is thicker than the edges.

Front 8

reflecting telescope

Back 8

a telescope that uses a curved mirror to collect and focus light.

Front 9

radio telescope

Back 9

a device used to detect radio waves from objects in space.

Front 10

observatory

Back 10

a building that contains one or more telescopes.

Front 11

constellation

Back 11

an imaginary pattern of stars in the sky.

Front 12

spectograph

Back 12

an instrument that separates light into colors and makes an image of the resulting spectrum.

Front 13

apparent brightness

Back 13

the brightness of a star as seen from Earth.

Front 14

absolute brightness

Back 14

the brightness a star would have if it were at a standard distance from Earth.

Front 15

light-year

Back 15

the distance that light travels in one year, about 9.5 million million kilometers.

Front 16

parallax

Back 16

the apparent change in position of an object when seen from different places.

Front 17

Hertzsprung-Russell diagram

Back 17

a graph relating the surface temperatures and absolute brightness of stars.

Front 18

main sequence

Back 18

a diagonal area on an H-R diagram that includes more than 90% of all stars.

Front 19

nebula

Back 19

a large cloud of gas and dust in space, spread out in an immense volume.

Front 20

protostar

Back 20

a contracting cloud of gas and dust with enough mass to form a star.

Front 21

planetary nebula

Back 21

a huge cloud of gas that is created when the outer layers of a red giant star drift out into space.

Front 22

white dwarf

Back 22

the blue-white hot core of a star that is left behind after its outer layers have expanded and drifted into space.

Front 23

supernova

Back 23

the brilliant explosion of a dying supergiant star.

Front 24

neutron star

Back 24

the small, dense remains of a high-mass star after a supernova.

Front 25

pulsar

Back 25

a rapidly spinning neutron star that produces radio waves.

Front 26

black hole

Back 26

an object whose gravity is so strong that nothing, not even light, can escape.

Front 27

binary star

Back 27

a star system with two stars.

Front 28

eclipsing binary

Back 28

a binary star system in which one star periodically blocks the light from the other.

Front 29

open cluster

Back 29

a star cluster that has a loose, disorganized appearance and contains no more than a few thousand stars.

Front 30

globular cluster

Back 30

a large, round, densely-packed grouping of older stars.

Front 31

galaxy

Back 31

a huge group of single stars, star systems, star cluster, dust, and gas bound together by gravity.

Front 32

quasar

Back 32

an enormously bright, distant galaxy with a giant black hole at its center.

Front 33

spiral galaxy

Back 33

a galaxy with a bulge in the middle and arms that spiral outward in a pinwheel pattern.

Front 34

elliptical galaxy

Back 34

a galaxy shaped like a round or flattened ball, generally containing only old stars.

Front 35

irregular galaxy

Back 35

a galaxy that does not have a regular shape.

Front 36

universe

Back 36

all of space and everything in it.

Front 37

scientific notation

Back 37

a mathematical method of writing numbers using powers of ten.

Front 38

big bang

Back 38

the initial explosion that resulted in the formation and expansion of the universe.

Front 39

Hubble's law

Back 39

the observation that the further away a galaxy is, the faster it is moving away.

Front 40

cosmic background radiation

Back 40

the electromagnetic radiation left over from the big bang.

Front 41

solar nebula

Back 41

a stream of electrically charged particles that emanate from the sun's corona.

Front 42

planetesimal

Back 42

one of the small asteroid-like bodies that formed the building blocks of the planets.