Astrophysics

• The universe is a large collection of billions of galaxies
• A galaxy is a large collection of billions of stars
• Our solar system is in the milky way galaxy
• Gravitational field strength


  Increases as the mass of an object increases
• Planets that have a larger mass have a stronger gravitational field strength
• Gravitational force


  Causes moons to orbit planets, planets to orbit the sun, artificial satellites to orbit the Earth, and comets to orbit the sun
• Orbit of planets around stars (e.g. The sun)


  Have an almost circular shape
• Orbit of comets


  Have an elliptical shape
• Ways to classify stars

  • Colour
  • Size
  • Temperature
• Star colour


  Relates to its temperature - red is cooler, blue is hottest
• Evolution of a star

  Nebula --> main sequence star-> red giant -> white dwarf
• Evolution of a star bigger than the sun

  Nebula --> main sequence star -> red supergiant --> supernova--> neutron star/black hole
• Big bang theory


  The theory that everything ever to exist was made from the explosion of a singularity 13.8 million years ago, and the universe is still expanding since then
• Cosmic background radiation is a small amount of radiation that is present all of the time, suggesting it is remaining radiation form the big bang
• Redshift- the phenomenon of light from distant galaxies which has been recorded to have been continuously moving away from the Earth and the planets from each other
• If a wave source moves relative to an observer

  There will be a change in wavelength and frequency