astrophysics

• The solar system contains all the planets you've heard of, in order starting closest to the Sun: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune
• Galaxy


  A collection of billions of stars
• Universe


  Made up of billions of galaxies
• The Milky Way is the name of the galaxy we live in
• Gravitational pull


  Keeps planets orbiting the Sun, moons orbiting planets, artificial satellites orbiting Earth, and comets orbiting the Sun
• Satellite


  Any object that orbits a planet, including both artificial and natural satellites
• Comet


  Has an elliptical orbit, travels fastest when closest to the Sun due to increased gravitational pull
• Strength of gravitational pull


  Depends on the mass of the planet and the distance from the Sun
• Star colour


  Hot stars appear blue, cool stars appear red, middling stars appear orange
• Absolute brightness


  Brightness of a star as if it were the same distance away
• Apparent brightness


  Brightness of a star as seen from Earth
• Luminosity


  Measure of the amount of light energy given off by a star every second
• Life cycle of a small star (like the Sun)

  1. Nebula forms from dust and gas

  2. Gravitational pull brings it together

  3. Starts burning hydrogen fuel (main sequence)

  4. Runs out of hydrogen, burns helium, swells into red giant

  5. Turns into white dwarf, then black dwarf
• Life cycle of a large star

  1. Nebula forms from dust and gas

  2. Gravitational pull brings it together

  3. Starts burning hydrogen fuel (main sequence)

  4. Turns into supergiant

  5. Supernova explosion

  6. Leaves behind neutron star or black hole
• Hertzsprung-Russell diagram


  Compares luminosity and surface temperature of stars to determine their life cycle stage
• The Big Bang Theory states that the universe originated from a single point and then rapidly expanded
• Cosmic microwave background radiation (CMBR)


  Provides evidence for the Big Bang Theory
• Redshift


  Increase in wavelength of light from distant galaxies, evidence that they are moving away, supporting the Big Bang Theory
• Doppler effect


  Change in wavelength of waves (sound or light) due to relative motion of the source and observer
• Galaxy moving away


  Light from that galaxy is redshifted
• Galaxy moving closer


  Light from that galaxy is blueshifted
• Calculating galaxy speed from redshift

  1. Use equation: change in wavelength / reference wavelength = speed of galaxy / speed of light

  2. Plug in known values to solve for galaxy speed
• The light from the distant galaxy has been redshifted, indicating the galaxy is moving away
• The gravitational field strength on Mars is 4 times that on Earth
• Calculating orbital radius of Deimos

  1. Use equation: orbital speed = 2πr / orbital period

  2. Plug in known values for orbital speed and orbital period to solve for orbital radius
• explain that gravitational force: • causes moons to orbit planets • causes the planets to orbit the Sun • causes artificial satellites to orbit the Earth • causes comets to orbit the Sun