Space

Question 1

What is a star?

Answer 1

A star is a large ball of gas - mostly hydrogen and helium that undergoes nuclear fusion

Question 2

What is a light year?

Answer 2

The distance travelled by light, in a vaccum, in 365 days

Question 3

What is a parsec and what is it used for?

Answer 3

A parsec is 3.26 light years (ly) - used to figure out how far a star is - with the sun as reference

Question 4

How can stars differ from each other?

Answer 4

They can vary in size, mass, temperature and brightness

Question 5

If a star is bright, what does that indicate?

Answer 5

A brighter star indicates a higher apparent magnitude

Question 6

How does a star get energy?

Answer 6

The gases that make up the star are constantly reacting at the core and provide energy for the star when it undergoes nuclear fusion - this energy is emitted as light, which is what we see in the night sky

Question 7

What is nuclear fusion?

Answer 7

When two light atomic nuclei join together to form a single heavier nuclei.

Question 8

What does a stars brightness mean? - Apparent magnitude

Answer 8

The brightness of a star viewed from Earth can be measured using a scale called the apparent magnitude scale - a measure of how bright it “appears” to be. The sun is the brightest star we can see, and it has an apparent magnitude of -27. The more positive the number, the dimmer the star.

Question 9

What does a stars brightness mean? - Absolute magnitude

Answer 9

Measures the brightness of a star as if they are all the same distance from Earth - the actual brightness/luminosity. If a star is hotter and further away it will have a higher absolute magnitude

Question 10

What does a stars colour mean?

Answer 10

The colour of a star depends on its surface temperature

Question 11

What stars are the hottest/coolest?

Answer 11

Hotter stars are blue and colder stars are red - can use the Hertzsprung Russel diagram to show this

Question 12

What is a galaxy?

Answer 12

When groups of stars are held together by gravity

Question 13

What is a nebulae?

Answer 13

A giant cloud of gas and dust in space

Question 14

What do small stars do when they die?

Answer 14

Small stars will cool and die, forming white and black dwarfs

Question 14

What do big stars do when they die?

Answer 14

Big stars will explode into novas and supernovas - releasing large amounts of energy and light

Question 15

What happens to the rest of the star when it dies?

Answer 15

The remaining core of the star becomes a neutron star

Question 16

How are stars born?

Answer 16

When there is a nebulae - a cloud of gas and dust made of hydrogen. lots of hydrogen atoms = greater attraction force - there is a lot of pressure in the gas cloud, causing it to heat up. when there is enough heat, the atoms form together to make helium - this nuclear fusion releases large amount of heat and light energy

Question 17

Draw the life cycle of a star:

Answer 17

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Question 18

How can you determine the elements present in the universe?

Answer 18

Elements will absorb light in specific wavelengths - creating an absorption spectrum, when they return to a stable state, they release the same wavelengths as an emission spectrum

Question 19

What is the Doppler effect?

Answer 19

The change in the frequency of a wave as the object moves closer or away from the observer

Question 20

If an object is moving away from Earth, what way will it shift on the absorption spectrum?

Answer 20

An object moving further away means its wavelength will increase, the greater the redshift, the faster the object is moving away

Question 21

What is the Big Bang theory?

Answer 21

The universe developed from a small dense singularity into a massively expanded space

Question 22

What are the 3 pieces of evidence for the Big Bang theory?

Answer 22

1. Expansion of the Universe
2. Cosmic Microwave Background Radiation (CMBR)
3. Mixture of elements - abundance of H and He

Question 23

Evidence of the Big Bang - Expansion of the Universe

Answer 23

Redshift in galaxies - moving away from us. Light from an object moving away from us appears to have a longer wavelength - doppler effect.

Question 24

Evidence of the Big Bang - Mixture of elements - abundance of H and He

Answer 24

As shown by CMBR, the universe has cooled since the big bang. Energy cannot be created nor destroyed - meaning it must be converted into elementary matter. the simplest element to be made could be hydrogen

Question 25

Evidence of the Big Bang - Cosmic Microwave Background Radiation

Answer 25

When the Big Bang occured, large amounts of heat was released. CMBR is the leftover heat radiation. Today, the CMBR is very cold due to expansion and is nearly at absolute 0. It fills the entire universe - it is a form of electromagnetic radiation

Question 26

Big Bang vs Steady state theory

Answer 26

Big Bang:

• Universe started with a single source
• Matter in Universe was a hot dense ball of subatomic particles
• Universe is expanding and accelerating

Steady State:

• Universe has always existed
• Always has been the same and is never changing
• Universe is endless in space and time