M5- C20

Question 1

Astronomical unit

Answer 1

1.5 x10^11 m

Question 2

Light year

Answer 2

9.46x10^15 m

Question 3

Parsec

Answer 3

3.1x10^16 m

Question 4

Arcsecond

Answer 4

1/3600

Question 5

Stella parallax

Answer 5

Is a technique used to determine the distance to Stars that are relatively close to the earth, at distances less than 100pc

Question 6

Parallax angle p

Answer 6

p=1/d

Question 7

Wave source

Answer 7

A source of waves, such as light or sound - the object moving relative to an observer of the Doppler effect

Question 8

Doppler effect

Answer 8

The change in frequency and wavelength of waves received from an object moving relative to an observer compared with what would be observed without relative motion

Question 9

Blue shifted

Answer 9

Move towards the blue end of the spectrum, wave appears shorter
Galaxy moving towards the earth

Question 10

Red shifted

Answer 10

Galaxy moving away from Earth

Wavelength appears longer

Question 11

Hubbles law

Answer 11

The regression speed v of a galaxy is almost directly proportional to its distance d from the earth

Question 12

Homogeneous

Answer 12

Uniform in terms of the distribution of matter across the universe when viewed on a sufficiently large scale

Question 13

Isotopic

Answer 13

The same in all directions (for example the universe, appearing the same to any observer regardless of position)

Question 14

Big Bang

Answer 14

The theory that at any moment in the past all the matter in the universe was contained in a singularity, the beginning of space and time, that expanded rapidly outwards

Question 15

Dark energy

Answer 15

A hypothetical form of energy that fills all of space and would explain the accelerating expansion of the universe

Question 16

Dark matter

Answer 16

A hypothetical form of matter spread throughout the Galaxy that neither emits nor absorbs light- it could explain the difference between the predicted and observed velocities of the stars in galaxies