The Universe

Question 1

What is a star?

Answer 1

A spherical object giving off heat and light due to nuclear fusion.

Question 2

What is a Solar System?

Answer 2

A solar system refers to a star and all the natural objects that travel in orbit around it.

Question 3

Star life cycle

Answer 3

Stellar Nebula
1. Average star - red giant - planetary nebula - white dwarf
2. Massive star - red supergiant - supernova - neutron star/black hole

Question 4

Accretion

Answer 4

Growth of a body by gathering or aggregating more matter due to gravitational forces.

Question 5

What does the absolute brightness of a star depend on?

Answer 5

Its mass

Question 6

How does a star start its life? Due to …… what does it form?

Answer 6

A star starts its life as a nebula. Due to gravity, forms a protostar.

Question 7

How does a protostar form?

Answer 7

The gas in a nebula condenses, losing gravitational potential energy and gaining kinetic energy, raising the temperature of the atoms.

Question 8

What is our galaxy called and what type is it?

Answer 8

The milkyway. A spiral galaxy.

Question 9

What does our solar system consist of?

Answer 9

The sun, eight planets and their natural satellites.

Question 10

What are the natural satellites?

Answer 10

Moons, dwarf planets, asteroids and comets.

Question 11

Name and describe our galaxy.

Answer 11

The milky way is a huge collection of stars, dust and gas. It is called a spiral galaxy.

Question 12

Calculations involving E=mc^2

Answer 12

For every 1 kg of mass you turn into energy, you get 9x10^6 joules of energy out. This shows mass and energy are interchangeable.

Question 13

Describe the difference between the apparent and absolute brightness of a star.

Answer 13

A main sequence stars absolute brightness tells us their mass (not size). The absolute brightness of a star is the total energy radiated by a star per second. The apparent brightness is the brightness of the star measured from earth.

Question 14

Color of stars in increasing order of hotness.

Answer 14

Red, yellow, white, blue.

Question 15

State what the Big Bang model of the universe means.

Answer 15

The Big Bang model is the current accepted model for the origin of the universe. This term is used to describe the rapid expansion of the very early universe from a hot, dense concentration of matter.

Question 16

Describe a galaxy.

Answer 16

Galaxies are groups of millions of stars held together by gravitational forces.

Question 17

Wiens law.

Answer 17

Dominant wavelength = constant/temp in kelvin.

Question 18

State two pieces of evidence supporting the Big Bang model.

Answer 18

1. Red shift.
2. Cosmic microwave background radiation.

Question 19

What is a light year?

Answer 19

A light year is the distance light travels in one year.

Question 20

Explain why light year is used as an astronomical measurement of distance.

Answer 20

A light year is the distance light travels in one year.Astronomers use light years to measure the distances between stars because of how big space is.

Question 21

What is a nuclear fusion reaction?

Answer 21

When small nuclei fuse together to form larger nuclei. The energy main sequence stars release is generated from nuclear fusion reactions involving hydrogen nuclei fusion to form helium nuclei in the core of the star.

Question 22

What happens during a nuclei fusion reaction?

Answer 22

In this process nuclear potential energy is converted into other forms of energy.

Question 23

What is a nebula?

Answer 23

A star starts its life cycle as a nebula, which due to gravity forms a protostar. Regions of intergalactic clouds of dust and gas are called nebulae.