(SP7) Astronomy

Question 1

Ptolemy’s Geocentric Model

Answer 1

Planets orbit the Earth

Question 2

Copernicus’ Heliocentric Model

Answer 2

Planets orbit the Sun

Question 3

Advances in modern day astronomy (4 points)

Answer 3

1) Photography
2) Computers
3) Telescopes in orbit
4) Space probes

Question 4

Uses of artificial satellites (5)

Answer 4

• communications
• Global Positioning System (GPS)
• map making
• scientific surveys
• spying

Question 5

Life cycle of solar mass stars

Answer 5

1) Nebula - cloud of dust and hydrogen that collapses due to gravity (increase KE => thermal energy) => denser

2) Protostar - H->He+energy
When the equilibrium reached (the outwards pressure from the hot gases=the inwards compression due to gravity) protostar becomes a main sequence star.

3) Main sequence star (10 billion years)
When the star runs out of hydrogen, fusion decreases and the core collapses (gravity overcomes thermal energy) outer layers expand.

4) Red Giant - bigger star in which fusion process begins again, He->heavier elements
5) Shell of gas is formed because heavier elements are formed. As the core runs out of fuel again => it collapses into a white dwarf
6) White dwarf - no fusion, temperature decreases, cooler + dimmer

Question 6

Life cycle of Massive Stars

Answer 6

3) Massive main sequence star - more mass=more fusion, higher temperatures, brighter
As H runs out core collapses => red supergiant

4) Red supergiant - condition for fusing heavier elements
When the fuel runs out core collapses, outer layers bounce off -> core explosion -> supernova

5) Supernova - extremely bright
6) Black hole or Neutron star

Question 7

Doppler Effect

Answer 7

If waves are red-shifted they are moving away from us. The further the lines are shifted = the faster the star is relative to us.

Question 8

Hubble’s Law

Answer 8

Everything is moving away from us -> the galaxy is explanding

Question 9

Big Bang theory

Answer 9

The whole Universe and all the matter in it was concentrated into a single incredibly tiny point of concentrated energy.
It began to enlarge rapidly in a hot explosion and it is still expanding today.

Cosmic Microwave radiation provides supporting evidence for the Big Bang theory.

Question 10

Steady State Theory

Answer 10

The Universe has always existed (no beginning, no end)