universe vocab

Question 1

absolute magnitude

Answer 1

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

Question 1

apparent magnitude

Answer 1

the brightness of a star as seen from Earth

Question 2

galaxy

Answer 2

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

Question 3

H-R diagram

Answer 3

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

Question 4

light-year

Answer 4

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

Question 5

luminosity

Answer 5

the actual brightness of an object such as a star

Question 6

main sequence

Answer 6

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

Question 7

nebula

Answer 7

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

Question 8

neutron star

Answer 8

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 9

planet

Answer 9

a relatively large spherical body that orbits a star

Question 10

pulsar

Answer 10

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

Question 11

revolution

Answer 11

th emotion of a body that travels around another body in space; one trip along an orbit

Question 12

rotation

Answer 12

the spin of a body on its axis

Question 13

solar system

Answer 13

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

Question 14

star

Answer 14

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

Question 15

wavelength

Answer 15

the distance between two adjacent troughs or crests of a wave

Question 16

supernova

Answer 16

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

Question 17

universe

Answer 17

space and all the matter and energy in it

Question 18

white dwarf

Answer 18

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

Question 19

spiral galaxy

Answer 19

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

Question 20

elliptical galaxy

Answer 20

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

Question 21

irregular galaxy

Answer 21

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

Question 22

electromagnetic spectrum

Answer 22

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

Question 23

big bang theory

Answer 23

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 24

cosmic microwave background

Answer 24

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

Question 25

redshift

Answer 25

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

Question 26

doppler effect

Answer 26

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

Question 27

spectroscope

Answer 27

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