earth and space term 2 test

Question 1

define planets

Answer 1

planets orbit stars
orbit our sun (a star)
9 planets
They are always lower mass than the star itself.

Question 2

define exoplanets

Answer 2

Exo-planets orbit other stars.
They are always lower mass than the star itself.
4000-5000 exoplanets.

Question 3

define star

Answer 3

massive, luminous sphere of plasma, held together by it’s own gravity.

Question 4

define double/triple star

Answer 4

stars that appear to “twinkle” and constant change colour in the sky are actually 2 or 3 stars spinning around each other.

Question 5

define nebula

Answer 5

A cloud of gas and dust in outer space
Some nebulae are the result of stars dying and then exploding.
The Nebula is a lot larger than the star which formed it.

Question 6

define star clusters

Answer 6

tightly packed groups of stars gravitationally bonded together
found in galaxies

Question 7

define galaxy

Answer 7

A system of millions or billions of stars, together with gas and dust, held together by gravitational attraction.

Question 8

define black hole

Answer 8

A region of space having a gravitational field so intense that no matter, radiation or light can escape.
The black circle right is a black hole. The red/yellow part is stars and other matter getting sucked into the black hole.

Question 9

define the universe

Answer 9

The universe is everything. All of space and time.

Very large.

Question 10

define main sequence star

Answer 10

A distinctive type of star which fuses Hydrogen into Helium

Question 11

define red giant

Answer 11

formed when the hydrogen of a medium star runs out

Question 12

define planetary nebula

Answer 12

is a cloud of gas formed when the helium of a red giant runs out.

Question 13

define supergiant

Answer 13

is formed when a larger main sequence star’s hydrogen runs out.
They are very hot so they start off as blue stars but as they cool they become redder

Question 14

define white dwarf

Answer 14

is formed when the gases of a planetary nebula disperse very hot core remains.
very dense
very hot
much dimmer than the red giants

Question 15

define black dwarf

Answer 15

is the cold dark remains of a white dwarf when it has cooled.

Question 16

define supernova

Answer 16

A star that suddenly increases greatly in brightness because of a catastrophic explosion that ejects most of its mass.

Question 17

define neutron star

Answer 17

is a star formed entirely from neutrons.

very dense

Question 18

Define astronomical unit

Answer 18

one astronomical unit is equal to the distance from our earth to our sun

Question 19

define light year

Answer 19

a light year is how far light travels in one year and equal to how many years back in time

Question 20

define parsec

Answer 20

parallax second equal to 3.26 light-years

Question 21

what is the location of star clusters?

Answer 21

open clusters are mostly in the flat “galactic disc”

globular clusters orbit our galaxy in the “galactic halo”

Question 22

define characteristics of globular star clusters

Answer 22

More than 50 parsecs in size,

sometimes much more!Spherically Shaped

Question 23

define characteristics of open star clusters

Answer 23

Less than 5 parsecs in size,

usually much less ! Irregularly Shaped

Question 24

define the apparent magnitude and two factors that influence it

Answer 24

the measure of how bright the star will appear to an observer on earth

two factors:

• how much light the star emits
• distance between the observer and the star ( smaller distance = greater brightness)

Question 25

define absolute magnitude

Answer 25

determined by actual brightness

Question 26

define star magnitude

Answer 26

the brightness of a star is its magnitude
brighter the star smaller the magnitude
brightest stars often have negative magnitudes

Question 27

What is the doppler effect?

Answer 27

an increase or decrease in the frequency of a wave as the wave source and the observer move towards/away from each other

Question 28

define redshift?

Answer 28

the object moving away from us

Question 29

define blue shift?

Answer 29

the object is moving towards us

Question 30

What is cosmological redshift?

Answer 30

the stretching of starlight due to the expansion of space

Question 31

define the big bang theory?

Answer 31

The leading scientific explanation about how the universe began.

Question 32

How do you calculate the age of the universe?

Answer 32

Step 1 – measure the gradient (rise/run) to find Hubble’s constant (Ho)
Step 2 – convert the units so they can be compared (get everything into m or km instead of parsecs)
Step 3 – find the inverse of the number you obtain instep 2 (1/x or x-1)

Question 33

define star colour

Answer 33

The colour of a Star is an indication of the Star’s temperature. Blue is the highest temperature and red the lowest.

Question 34

how many stars are needed for it to be called a cluster

Answer 34

10,000

Question 35

what galaxy are we in?

Answer 35

milky way

Question 36

what is the basic lifecycle of a star?

Answer 36

the nebula to main-sequence stars.

from main sequence route a is to supergiant, supernova then either black hole or neutron star

route b is red giant, planetary nebula, white dwarf, white dwarf cooling, black dwarf

Question 37

What were some of Hubble’s observations

Answer 37

the galaxies further away were more red-shifted than galaxies closer to us

galaxies are moving away faster as distance increases (expansion of the universe)

Question 38

how to identify the age of star clusters from HR diagrams

Answer 38

anything in main sequence line is young

anything spread out, under/above the main sequence is old