Space

• Life cycle of stars

  1. Big cloud of dust and gas (nebula)

  2. Gravity pulls dust and gas together to form a protostar

  3. Protostar gets bigger and denser

  4. Temperature and pressure increase

  5. Hydrogen nuclei fuse to form helium (nuclear fusion)

  6. Star becomes a main sequence star

  7. Main sequence star has balanced outward and inward pressure

  8. Star runs out of hydrogen

  9. Gravity contracts star

  10. Nuclear fusion forms heavier elements up to iron

  11. Small/medium star becomes a red giant

  12. Red giant expels outer layers, leaving a white dwarf

  13. White dwarf cools to become a black dwarf

  14. Massive star becomes a red supergiant

  15. Red supergiant explodes in a supernova

  16. Supernova ejects heavy elements

  17. Massive star condenses into a neutron star or black hole
• Nebula


  Big cloud of dust and gas
• Protostar


  Structure formed as gravity pulls dust and gas together
• Nuclear fusion


  Process where hydrogen nuclei fuse to form helium, releasing energy
• Main sequence star


  Star where outward pressure from nuclear fusion is balanced by inward pressure of gravity
• Red giant


  Star that forms when a small/medium star runs out of hydrogen
• White dwarf


  Hot, dense core left behind when a red giant expels its outer layers
• Black dwarf


  White dwarf that has cooled and no longer emits light
• Red supergiant


  Star that forms when a massive star runs out of hydrogen
• Supernova


  Explosion of a red supergiant, ejecting heavy elements
• Neutron star


  Dense core left behind when a massive star explodes in a supernova
• Black hole


  Extremely dense object formed when a truly massive star collapses in on itself
• Asteroid


  Asteroid belt

  Rock, metal
• Comet


  More elliptical orbits

  Reach the outskirts of the solar system

  Ice and dust
• Redshift


  The phenomenon where the light from distant galaxies appears shifted towards the red end of the spectrum
• Big Bang


  The theory that the universe began in a tiny, extremely dense and hot state, and has been expanding and cooling ever since
• From Earth, every direction we look into space, the galaxies seem to be moving further and further away from us, or in other words, the universe is expanding
• Absorption spectrum


  The pattern of dark lines in the spectrum of visible light emitted from the sun, caused by certain wavelengths being absorbed by chemicals in the sun's atmosphere
• Light from distant galaxies

  Shows a redshift, with the absorption lines shifted towards the red end of the spectrum
• The further away a galaxy is, the faster it appears to be moving away from us
• Models have limitations, but are still useful for understanding difficult concepts