1. The Sun and the Origin of the Solar System

2. Mid-sized, G-type main sequence star Distance: 1 AU = 150 million km away Size: Actual radius 700,000 km = 100 Earths Temperature, Luminosity (surface) T = 6000 K http://www.nasa.gov/multimedia/videogallery/i ndex.html

5. 99.86% of the total mass of the Solar System 75% hydrogen, 23% heliun 2% O, C, Ne, Fe

7. Sunspots surface areas that are darker than surroundings (lower temperatures) regions of intense magnetic activity

9. Solar Evolution

10. Star (Sun) formation

11. Stellar Evolution The Sun is a middle-aged, low-mass, main-sequence star 5 billion years ago: – Beginning of its life on main-sequence – Sun had 1/3 luminosity it has now. 5 billion years from now: – End of its life on main-sequence – Sun will have twice the luminosity it has now.

12. When H is exhausted, core shrinks. Heats up High temperatures ignites a shell of H around the core. Increased pressure drives the envelope of the star outward. Creates a Red giant

13. – Contraction of core, raises the temperature – Ignites He shell around the core – Eventually the core stabilizes – Envelope is ejected as a "planetary nebula" – The core remains as a "white dwarf"

16. Solar system formation Starting point: – A cloud of interstellar gas and dust, the "solar nebula“ – Most of it (98%) is hydrogen and helium, includes dust grains of heavier material, formed in previous generations of stars.

17. Contraction Accretion disk Protostar Condensation Planetesimals

18. http://www.youtube.com/watch?v=5l5mB-rFuGo

19. Asteroid Belt Small bodies in the inner solar system Asteroid Belt between Mars & Jupiter. Orbits are strongly influenced by Jupiter. Made of rock, metal, or a mix of the two.

20. >300,000 asteroidal objects >150,000 with good enough orbits to give official numbers ~15,000 asteroids with official manes When you know its orbit, you can name it.

21. Examples of asteroid names Ceres (largest – 914 km) Eros (landed on in2001 Feb 12) Bach Beethoven Lennon McCartney Santana Clapton

22. Irregular shape Too small for gravity to make them spherical

23. Composition of Asteroids C-type: "Carbonaceous" – mostly carbon- bearing materials. ~75% of all asteroids. S-type: "Silicaceous" - mostly of silicates (stony or stony iron). 17% of all asteroids. M-type: "Metallic" - probably iron-rich

24. Asteroid Origins fragments of larger, differentiated bodies shattered by collisions remnants of more primordial material that never got differentiated

25. Impact with Earth Would disrupt climates and trigger mass extinctions

26. Meteoroids Chunks of rock & iron smaller than asteroids orbiting the Sun Sizes range from grains to 100 meters across

27. Meteor Streak of light when a meteoroid enters the Earth's atmosphere Most are tiny grains Meteor showers are trails of debris left behind by passing comets

28. Meteorite Any remnant that reaches the ground intact.

29. Russian Meteorite http://www.youtube.com/watch?v=90Omh7_I 8vI http://www.youtube.com/watch?v=90Omh7_I 8vI

30. Meteor Impacts About 100 tons of meteoroids hit the Earth each day Most are no bigger than grains of sand or smaller

31. Earth Impact Effects Program http://impact.ese.ic.ac.uk/ImpactEffects/

32. Comets Small bodies consisting of aggregates of ices mixed with rock & dust

33. As they approach the Sun, they heat up and the ices sublimate (go from solid to gas):

34. Halley's Comet In 1705, Edmund Halley computed the orbit of the great comet of 1682 using Newton's laws Found that orbit of 1682 comet was the same as comets seen in 1531 & 1607. Predicted return in 1758. Seen again on Christmas day 1758, 12 years after Halley's death

35. Origin of Comets Short-period comets are from the Kuiper Belt Long-period comets are from the Oort Cloud

36. Structure of Comets Nucleus: – Dirty snowball of ices & dust – >99% the mass of the comet Coma – Bright "head" of the comet – Low-density cloud of gas & dust sublimed off the nucleus – Extends out to 100,000 km or more

37. Comets have two tails – Dust Tail, dusty particles swept back in a curved path by solar radiation, white – Ion Tail, ionized atoms & molecules swept straight back by the solar wind, blue

38. Comet Orbits Typically have a high degree of eccentricity http://www.windows2universe.org/comets/com et_model_interactive.html

39. Kuiper Belt Region of the Solar System beyond the planets extending from the orbit of Neptune (at 30 AU) to approximately 55 AU from the SunSolar SystemorbitNeptune AU Sun

40. Oort Cloud Cloud of comets which may lie roughly 50,000 AU, or nearly a light-year, from the Sun.comets AUlight-yearSun Nearly a quarter of the distance to Proxima Centauri, the nearest star to the SunProxima Centauristar