P2h

Question 1

What is the stages of a star?

Answer 1

1-initially form from clouds of dust and gas
2-force of gravity make gas and dust spiral together to form a protostar. Gravitational energy has been converted into heat energy, so temperature rises
3-main sequence star
4-hydrogen begins to run out and star swells to a red giant
5-small to medium sized stars become a planetary nebula
6-the a white dwarf
7-big stars become super red giants
8-then a neutron star and maybe onto a black hole

Question 2

How does a star become a main sequence star?

Answer 2

• high temperature causes hydrogen nuclei to undergo thermonuclear fusion to form helium nuclei and give out massive amounts of heat and light
• star is born
• immediately enters a stable period where heat created by nuclear fusion provides an outward pressure to balance the force of gravity pulling everything inwards
• typically lasts several billion years

Question 3

What happens to big stars?

Answer 3

1-big stars form red giants–they start to glow brightly against as they undergo more fusion and expand and contact several times, forming heavier elements in various nuclear reactions. Eventually exploding into a supernova.
2-exploding supernova throws outer layers of dust and gas into space leaving a very dense core called a neutron star. If big enough this will become a black hole

Question 4

What happens to smaller stars?

Answer 4

1-small to medium sized stars become unstable and eject layers of dust and gas as a planetary nebula
2-leaving behind a hot, dense solid core (white dwarf) which cools down and eventually fades away

Question 5

What was the Ptolemaic model?

Answer 5

• Sun, Moon, planets and stars orbit the Earth

- geocentric model

Question 6

What is the Copernican model?

Answer 6

• heliocentric model

- shows that the sun is the centre of the universe and Earth and plants all orbit it in perfect circles

Question 7

What evidence did Galileo find to support Copernican’s model?

Answer 7

• using a telescope he saw that some stars were in a line to Jupiter and never moved and seemed to be carried along by the planet
• suggesting that they weren’t stars but moons
• evidence that not everything orbits around the Earth

Question 8

Why were people against Copernicus’ ideas?

Answer 8

• the current geocentric models had been around for a long time
• the church claimed they went against the Bible, which said Earth was the centre of the universe

Question 9

What are the modern changes of the the Copernican Model?

Answer 9

• sun is not really the centre of the universe

- plants orbit the Sun in an elliptical orbit, not perfect circles