Unit 6 Vocabulary

Question 1

absolute magnitude

Answer 1

a brightness scale used to measure of how bright a star would be if it were seen from a standard distance

Question 2

apparent magnitude

Answer 2

the brightness of a star as seen from Earth

Question 3

galaxy

Answer 3

a large collection of stars, dust, and gas bound together by gravity

Question 4

H-R diagram

Answer 4

Hertzsprung-Russell diagram, a graph that shows the relationship between a star’s surface temperature and absolute magnitude

Question 5

light-year

Answer 5

the distance that light travels through space in one year; about 9.46 trillion kilometers

Question 6

luminosity

Answer 6

the actual brightness of an object such as star

Question 7

main sequence

Answer 7

the region on the H-R diagram where stars spend most of their lives; it has a diagonal pattern

Question 8

nebula

Answer 8

a large cloud of dust and gas in interstellar space; a region in space where stars are born

Question 9

neutron star

Answer 9

the core of a supernova that has collapsed under gravity to the point that the electrons and protons have smashed together to form neutrons

Question 10

planet

Answer 10

a relatively large spherical body that orbits a star

Question 11

pulsar

Answer 11

a highly magnetized, rotating neutron star that emits a beam of electromagnetic radiation

Question 12

revolution

Answer 12

the motion of a body that travels around another body in space; one trip along an orbit

Question 13

rotation

Answer 13

the spin of a body on its axis

Question 14

solar system

Answer 14

the collection of large and small bodies that orbit our central star, the sun

Question 15

star

Answer 15

a large celestial body that is composed of gas and that emits light; the sun is a typical star

Question 16

wavelength

Answer 16

the distance between two adjacent throughs or crests of a wave

Question 17

supernova

Answer 17

a gigantic explosion in which a massive star throws its outer layers into space, but its core remains

Question 18

universe

Answer 18

space and all the matter and energy in it

Question 19

white dwarf

Answer 19

the hot, dense, dim core of matter that remains from the collapse of a low-mass star

Question 20

spiral galaxy

Answer 20

a galaxy shaped like a pinwheel, with a bulge in the center and spiral arms extending outward

Question 21

elliptical galaxy

Answer 21

a spherical or elongated galaxy with a bright center and very little dust and gas

Question 22

irregular galaxy

Answer 22

a galaxy with an irregular shape that does not fit into any other category

Question 23

electromagnetic spectrum

Answer 23

all of different wavelengths and frequencies of electromagnetic radiation, from radio waves to gamma rays

Question 24

big bang theory

Answer 24

the theory that all matter and energy in the universe was compressed into an extremely small volume that 13 billion to 15 billion years ago exploded and began expanding in all directions

Question 25

cosmic microwave background

Answer 25

CMB; the electromagnetic radiation left over from the formation of the universe

Question 26

red shift

Answer 26

a phenomenon which occurs when a star or galaxy is moving away from the earth and its

Question 27

doppler effect

Answer 27

and observed change in frequency or wavelength when the source is moving with respect to observer

Question 28

spectroscope

Answer 28

a tool used to collect light from stars and separate the colors in the light