31.1 31.2

Question 1

constellation

Answer 1

many of the names givin to these groups of stars by ancient cultures remain today

Question 2

radio-telescope

Answer 2

a radio-telescope collects and amplifies radio waves

Question 3

light-year

Answer 3

is the distance light travels in one year

Question 4

spectroscope

Answer 4

uses a prism or diffraction grating to separate light into its component wavelengths

Question 5

nebula

Answer 5

particles within the cloud exert gravitational forces on each other,causing the cloud to contract, and the temperature to increase

Question 6

main sequence

Answer 6

stars include the broad band of star from the hot, bright stars in the upper left corner of the diagram to the cool, dim stars in the lower right corner

Question 7

giant

Answer 7

as the core heats up, the star outer layers expand and cool

Question 8

white dwarf

Answer 8

forms as the core of a giant star no longer supports fusion and the star outer layers escape into space leaving a hot and dense core

Question 9

supernova

Answer 9

is a gigantic explosion in which the temperature within the collapsing star is 10 billion k and the atomic nuclei in the core split into neutrons and protons.

Question 10

neutron star

Answer 10

when the star explodes it leaves behind a ball of neutrons called a neutron star

Question 11

black hole

Answer 11

is an area in space that is so dense that nothing can escape its pull of gravity

Question 12

photosphere

Answer 12

is the layer of the sun that emits light into space

Question 13

sunspots

Answer 13

are dark, cool areas in the photosphere where the sun magnetic field has weakened