The Universe

The Universe

1. The Solar System

   • 8 Planets
     • 4 gas giants
     • 4 rocky planets
   • Comets -Eliptical orbits
   • Asteroids
     • meteorites
   • About 5 billion years old

2. Gravity

   • Weak form of attraction between objects
   • Depends on:
     • Size of masses
     • Distance apart

3. The Sun

   • Dust and gas clumps together by gravity
   • Mostly composed of hydrogen
     • By nuclear fussion, helium is made
       • Energy is given out

4. Galaxies

   • Billions of stars held together by gravity
   • We are in the Milky Way galaxy
     • It is a spiral galaxy
     • 100,000 light years wide

5. Expansion of Universe

   • Started with a 'big bang' at one central point
     • Approximately 13.7 billion years ago
   • Distance between galaxies increasing
     • The further apart the galaxies, the faster they move apart

6. Technology

   • Optical telescope 17th Century
     • Galilleo
     • Radio telescopes 1940's
       • Space telescopes
         • E.g. Hubble
   • Computer modelling
     • Can compare theories with data

7. Extra-Terrestrial Life

   • Evidence from Extremophiles on Earth
   • SETI -Searching for radio signals
   • Exoplanets discovered 1990's
     • Gases in atmospheres of exoplanets show signs of life
       • CO2, O2, H2O, CH4
   • Probes to other bodies in Solar System

8. Dark Energy

   • Rate of universe expanding seems to be increasing
     • Dark energy "pushes" it apart
   • Dark Matter
     • Discovered from gravitational lensing of distant galaxies
     • galaxies rotate too fast
     • There is more matter out there than we can detect