Astrophysics

Question 1

Planet orbits

Answer 1

• orbit the sun

- circular orbits

Question 2

Moon orbits

Answer 2

• orbits planets

- circular orbit

Question 3

Comet orbits

Answer 3

• orbit sun

- elliptical orbit

Question 4

To calculate orbital speed

Answer 4

Orbital speed = 2 pi x orbital radius / time period

V = 2 pi x r / T

Question 5

Evidence for Big Bang theory

Answer 5

• redshift (part of the Doppler effect. When light is moving away, there is a lower frequency and a high wavelength)
• CMBR (energy from the big bang released as light- detected everywhere in equal amount, suggesting that the universe was once very compact)
• Hubbles law- galaxies are moving faster the further away they get

Question 6

Big Bang theory- past evolution of the universe

Answer 6

• all mass/energy in the universe was in a single, small, dense entity
• something caused it to explode
• universe still expanding, no center point

Question 7

Absolute magnitude

Answer 7

The brightness of a star if it were a fixed distance away- accounts for distance

Question 8

Evolution of stars with a mass like the sun

Answer 8

• nebula - a big cloud of hydrogen and helium gas (formed in big bang) it condenses, attracted to itself by gravity
• protostar - forms into the centre of a disk of nebula
• main sequence star - where star spends most of its life
  
  • it fuses hydrogen into helium through fusion power
  • releases energy
• red giant - when hydrogen runs out helium fusion causes the star to expand
• white dwarf- end stage of small/medium stars (mostly carbon and very dense

Question 9

What happens to stars with a large mass

Answer 9

Instead of going to a white dwarf it goes to
- supernova - massive explosion bigger than a whole galaxy
- neutron star (remnants ore core, made of neutrons
OR
- black hole - light can’t escape due to gravity