Space

Question 1

How old is the universe?

Answer 1

13.7 billion years.

Question 2

Cosmology

Answer 2

The scientific study of the large scale properties of the universe.

Question 3

Evidence for the Big Bang theory

Answer 3

1. We are reasonably certain that the universe had a beginning
2. Expanding universe - galaxies appear to be moving away from us at speeds proportional to their distance.
3. Afterglow - cosmic microwave background radiation emitted within the universe now at a temperature of -270c
4. Elements in the universe - the abundance of the light elements.

Question 4

The Big Bang theory

Answer 4

The universe was through to have been concentrated into a single point of immense energy. An explosion within the first spilt seconds converted some of this energy to the simplest form of matter. Over time, the universe expanded and cooled and more complex matter formed.

Question 5

Red shift

Answer 5

A shift to lower or redder frequencies and results from a star’s movement away from the Earth.

Question 6

Blue shift

Answer 6

A shift to higher or bluer frequencies and is caused by a star’s movement towards the Earth.

Question 7

What colour has the longest wavelength and lowest frequency?

Answer 7

Red.

Question 8

What colour has the shortest wavelength and the highest frequency?

Answer 8

Violet.

Question 9

Doppler effect

Answer 9

The change in the wavelength of radiation recovers from objects moving relative to us. As a star moves away from us, the wavelength becomes longer and the star appears red. As a star moves towards us, the wavelength shortens and the star appears blue.

Question 10

Why are supernova events important?

Answer 10

Because it is within these violent explosions that heavy the heavy elements such as iron and lead are produced.

Question 11

Life cycle of stars

Answer 11

All stars form from interstellar matter called nebulae, comprised mainly of hydrogen gas. This is compressed together by the force of gravity until the heat and pressure cause nuclear fusion to begin. The star is born.

Question 12

How long is the life cycle of an average star?

Answer 12

10 billion years.

Question 13

Our suns life cycle #1-3

Answer 13

1. The sun evolves from a cloud gas. Gravity pulls it together. Pressure and temperature increase.
2. A protostar. A ball of super hot gas. Contraction continues.
3. Fusion starts in the core. The star joins the main sequence. Our sun will be on it for about 10 million years.

Question 14

Our suns life cycle #4-5

Answer 14

4. Hydrogen in the core begins to run out. Hydrogen in the outer layers starts to fuse causing expansion. The star becomes a red giant.
5. The outer layers are ejected into space forming a planetary nebula. We are left with a very dense, hot white dwarf.

Question 15

Outline two ways in which stars in the night sky can differ from each other.

Answer 15

1. How bright they are

2. Their colour

Question 16

What are some of the ideas people have put forward about how the universe was formed?

Answer 16

1. Creationism - that God created heaven and Earth.
2. Aboriginal Dreamtime ideas.
3. Scientific theories - e.g the Big Bang theory.

Question 17

Apparent magnitude

Answer 17

A measure of how bright a star appears from Earth and is the result of the stars distance from the Earth and how much light it emits.

Question 18

Absolute magnitude

Answer 18

The amount of light a star emits.

Question 19

What factors determine apparent and absolute magnitude?

Answer 19

1. Size - larger stars tend to be brighter
2. Surface temperature - brighter stars are white and tend to have a higher surface temperature. Less brighter stars are red and tend to have a lower surface temperature.

Question 20

Nuclear fusion

Answer 20

A nuclear reaction in which multiple atoms combine under immense energy to create a star.

Question 21

Solar mass

Answer 21

A standard unit of mass that is used to indicate the masses of other stars.

Question 22

Is it likely that our sun may end its life in a supernova? Explain.

Answer 22

No, because it has a relatively low mass star. The sun will run out of hydrogen, explains up as a red giant, puff out its outer layers and settle down as a compact white dwarf.

Question 23

Red Giants

Answer 23

Thermonuclear fusing of helium to iron

Question 24

White dwarf

Answer 24

None

Question 25

Supernova

Answer 25

Once the core fails to produce enough energy to support the outer envelope of gases the star explodes as a supernova producing the bulk of elements beyond iron.

Question 26

Main Sequence Stars

Answer 26

Main Sequence Stars are stars that are thermonuclear fusing hydrogen atoms to form helium atoms in their cores. These process can go on for 10 billion years.