1. Bell Work Please pick up the notes sheet by the inbox

4. Orbiting between Mars and Jupiter are over 1 billion Asteroids, balls of solid rock left over from the formation of the Solar System. They range in size from marbles to giants 600 miles wide.

5. OCCASIONALLY ONE COMES OUR WAY

6. 65 Million years ago, a massive asteroid entered Earth’s atmosphere at a speed of 100,000 mph

7. IT WAS THEIR LAST DAY ON EARTH

8. It was an impact that shook the World

9. The asteroid was estimated to be 8 miles in diameter

10. It struck the shallow sea off the Yucatan Peninsula of Mexico, with a force equal to 700,000 nuclear bombs

11. The tremendous power of the impact could be seen clearly from space

12. A GIANT Tidal Wave 1200 feet high smashed outward, drowning coastal areas

13. Tremendous earthquakes and supersonic winds exceeding 800 miles/hr rushed across the land we now call North and South America The sound of the impact was loud enough to be heard on the other side of the Earth

14. It was the beginning of the end

15. Within 3 minutes, a 2-mile high wall of vaporized molten rock, steam and fire swept across what is now the Western United States and Central America. At the site of impact, the Gulf of Mexico boiled!

16. Intense heat incinerated all plants and animals up to 2,000 miles from center of impact A trillion tons of sulfur and rock debris were thrown high into the atmosphere

17. The impact produced a shroud of dust that blocked sunlight all over Earth, plunging the surface into darkness and cold for several years. Plants died worldwide, causing mass starvation of the animals, dinosaurs and fish that depended upon them. The result was the mass extinction of 70% of all life on the Earth. It was a planetary Extinction Level Event (E.L.E)

18. When the dust cleared years later, the crater left behind was 9 miles deep and 200 miles wide. Eventually, it was covered by erosion and has laid hidden from view for 65 million years

19. UNTIL NOW! By chance, this magnetic map of the seafloor taken during a search for oil by geologists in the Gulf of Mexico, discovered the crater in 1991

20. Knowing the location of the impact, scientists could now search worldwide for debris

21. THEY FOUND IT Strewn rocks: Recently discovered rocks blown out of the impact area some the size of small cars -- were found in Belize, more than 200 miles away Iridium: a mineral rare on Earth but common in asteroids, was found scattered throughout the world in a thin ash layer called the K-T Boundary

22. With no dinosaurs to eat them, small mammals who survived began to evolve into more complex creatures You had an ancestor who looked like this, alive during this event. You are in part, the result! They eventually took over the Earth

23. It could be said that humanity owes its existence to that asteroid impact so long ago

24. Dinosaur fossils + a few small mammals only K-T Boundary layer No fossils at all Small mammal fossils only Bigger mammals and a few reptile fossils Lots of extinct mammals and other life forms Modern life form fossils

25. KEY FACT SUMMARY Asteroid impact occurred 65 million years ago Hit Gulf of Mexico near Yucatan Peninsula It was an Extinction Level Event Crust cracked, lava pours out underwater Giant tidal waves, forest fires, ash and dust Sunlight blocked for years Plants and animals die from cold and no food 70% of all life including dinosaurs went extinct Surviving animals evolved into today’s species Fossils, crater, rocks, Iridium ash layer proof

26. Called the Cretaceous-Tertiary Impact, or K-T impact for short Crater is called Chicxulub

27. If the Earth was not hit by an asteroid 65 million years ago, what might the intelligent species on Earth look like today? Say Hello to Dinoman

28. It could happen again TOMORROW

29. The Asteroid belt is full of billions of asteroids

30. In fact … one of them has hit near here!

31. 35 million years ago … A huge comet about 2 miles in diameter struck the ground in a place that is now the Chesapeake Bay. The ocean was further East so there was no water. It left a huge crater and caused volcanic eruptions in the Appalachian Mountains. The hot springs near here are still being warmed by the volcanic magma under the mountains.

32. Two big asteroid fragments also hit Canada over 50 million years ago

33. This one hit Canada 200 million years ago

34. A comet struck Earth in 1908 over remote Siberia. Life was killed for thousands of square miles

35. An asteroid 600m in diameter hit Arizona 14,000 years ago

36. Every day, dozens of small asteroids hit earth

37. What is being done! Near Earth Objects Program - a NASA, MIT and Air Force project to use telescopes to locate 90% of all asteroids and comets in the Solar System that come anywhere near earth

38. What is being done EROS Flyby - a spacecraft named NEAR was sent to the Asteroid Belt to photograph EROS, (a large asteroid) and study asteroids up close. In March/2002, it actually landed on Eros

39. What is being done Comet Flybys - several spacecraft have been sent to intercept and study comets This one actually flew into comet Halley and took this picture before it crashed

40. What is being done Interception plans Engineers are beginning to explore ways that a comet or asteroid could actually be blown up. It cannot currently be done

41. Some definitions Asteroid - a rocky piece of the original nebula, orbiting the sun between Mars and Jupiter, and in the Kuiper Belt beyond Pluto –Asteroids are made almost entirely of rock and some traces of organic material. Very little ice

42. Major Asteroids Ceres - 600 miles in size (now dwarf planet) 2000 Varuna – about 560 miles in size Pallas - about 350 miles in diameter Vesta - about 315 miles in diameter Orbiting beyond Pluto Eris (dwarf planet) – 815 miles in diameter Quaoar – about 800 miles in diameter Sedna - 530 miles

43. Some definitions Meteor - An asteroid fragment or space rock that has entered earth’s atmosphere (also called a Shooting Star) –Meteors can be pieces of asteroids or of comets. Most burn up in the atmosphere –Meteorite – a meteor large enough to reach the ground

44. Woman hit by Meteor

45. Asteroid hits car in Peekskill, NY in 1992

46. Meteor Showers Passing comets leave tails of ice, rock and debris. If Earth passes through that tail, even years later, you have a shower of “meteors” enter Earth’s atmosphere

47. COMETS Comets are giant balls of dust, rock and ice (big dirty snowballs) that remain from the formation of the solar system 4.5 billion years ago. Comets range in size from 200 ft across to 800 miles across or more.

48. COMETS Billions of comets are thought to exist, orbiting the sun in two huge areas of space called the Kuiper Belt and the Oort Cloud.

49. COMETS Generally, comets stay in the area. On occasion, however, they collide with each other so that one of them is knocked out of orbit and falls toward the sun. Kuiper Belt Oort Cloud

50. COMETS When a comet comes close to the sun, its ice begins to melt and blow outward from the sun as a cloud of gas and water called the TAIL. The tail always points away from the sun. The rocky, icy center of the comet is the NUCLEUS The gas around the nucleus is called the COMA

51. COMETS When a comet comes close to the sun, its ice begins to melt and blow outward from the sun as a cloud of gas and water called the TAIL. The tail always points away from the sun.

52. Some famous COMETS Halley West Hale-Bopp

53. View of Halley’s orbit http://inquiry.ucsd.edu/flash/halley.swf