Meteoroids! Asteroids! Comets!

1. Meteoroids! Asteroids! Comets! Oh, my!

2. What makes up our Solar System? • The sun • Planets • Moons • Asteroid belt (between Mars and Jupiter) • Lots of space • All sorts of bits and pieces of rock

3. Meteorite, Meteoroid, Meteor? What’s the difference?

4. Meteorite vs. Meteoroid • Meteoroid = while in space a meteorite is called a meteoroid • Meteorite = a small rock or rocky grain that strikes Earth’s surface • So the difference is just based on where the rock is when you are describing it

5. Meteor • Sometimes called a “Shooting Star” • When a meteorite enters Earth’s atmosphere, friction causes them to burn up, producing a streak of light

6. Where do they come from?How big are they? • Pieces of rock that broke off other objects • Sizes range from as small as a pebble or as big as a huge boulder

7. Are they dangerous? • Most meteoroids disintegrate before reaching the earth by burning up in Earth’s atmosphere • Some leave a trail that lasts several minutes • Meteoroids that reach the earth are called meteorites. Large ones can cause damage

8. Flagstaff, Arizona • 49,000 years ago • Meteorite about 150 feet in diameter • Weighed 650 pounds • Energy = 2.5 million tons of dynamite • 4000 feet wide, 650 feet deep • Still visible today Barringer Meteorite Crater

9. What’s a “Meteor Shower”? • Usual rate = six meteors per hour • During a Meteor Shower = rate may be as high as 60 meteors per hour • Occur when Earth passes through the tail or debris of a comet • Presides (mid-August) • Leonids (mid-November)

10. Comets • Bodies in space made up of ice, dust, small gritty particles • Sometimes called “dirty snowballs” • When close to the sun, ice vaporizes, producing a spectacular streak of gas, referred to as a “tail” • Many in a regular orbit around the sun

11. Comets

12. Where do comets come from? • Many ordinate in a region called the Oort cloud which is located beyond the orbit of the dwarf planet Pluto • Others originate in the Kuiper Belt beyond the orbit of Neptune • This region is filled with billions of comets

13. Famous Comets • Comet Hale-Bopp • Halley’s Comet • Comet Kohoutek

14. A Comet’s Tail

15. Asteroids • An irregularly shaped rocky object in space (like a space potato) • May be the shattered remains of objects left over from the time when the planets were formed

16. How big are asteroids? • Larger than meteoroids • (In fact, the main difference between meteoroids and asteroids is their size.) • Size ranges from 10 feet across to bigger than a mountain

17. Asteroids • Approx. 150,000 asteroids in the Solar System • Most are in a band that orbit the sun between Mars and Jupiter (Asteroid Belt) • Why are there all of those asteroids between Mars and Jupiter and not another planet?

18. Near-Earth Asteroids (NEAs) • At least 1000 asteroids orbit outside of the Asteroid Belt – these could be a danger to Earth • Asteroids that cross Earth’s orbit are called Near-Earth Asteroids or NEAs • NEA / Earth collision not likely • But if it did, the affect of the impact would depend on the size of the asteroid

19. Large Asteroid hits Earth 65 Million Years Ago • Catastrophic Collision • Asteroid 6 to 12 miles in diameter • Near the Yucatan Peninsula in the Gulf of Mexico

20. Large Asteroid hits Earth 65 Million Years Ago • Collision produced an explosion = 100 trillion tons of dynamite • Gouged out a crater about 60 miles in diameter • How would an event like this affect Earth?

21. What do Scientists Think Happened? • Forests were wiped clean for a distance of 300 to 600 miles in all directions • 300 foot wave struck the coast of Texas • Powerful Earthquakes • Landslides destroyed long stretches of coastline

22. What do Scientists Think Happened • Explosion threw huge amounts of debris into the air, covering large parts of North America • Poisonous gases and dust soared high into the atmosphere, spread over most of the Earth, and then fell back onto the Earth’s surface

23. What do Scientists Think Happened • Sunlight was blocked from reaching the Earth’s surface for many months • Temperatures plummeted to the freezing point in normally warm areas • Not enough sunlight for photosynthesis • Plants died . . . Animals died • Many animals became extinct (including many types of dinosaurs)

24. The Rise and Fall of Life on Earth • See the dip around 65 Million years ago? • This represents the extinction of about 75% of all the species alive at that time.

25. Is the Earth in danger of a large asteroid impact? • Not that we know of! • None of the asteroids or comets discovered so far is on a collision course with Earth. • However, we can't speak for those that are not yet discovered. In principle, one of those could hit any time, but statistically the chances are very small.

26. Torino Scale • A system used to rate the hazard level of an object moving toward Earth

27. Review • Q: What is the difference between a meteoroid, meteororite, and a meteor? • Meteoroid = while in space a meteorite is called a meteoroid • Meteorite = a small rock or rocky grain that strikes Earth’s surface • Meteor = “Shooting Star”

28. Review • Q: What is the difference between an asteroid and a meteoroid? • The main difference is the size of the object. • Q: Which is larger, asteroid or meteoroid? • Asteroids are larger than meteoroids.

29. Review • Q: Why is it important to study smaller bodies in our Solar System such as comets or asteroids? • They help us learn about the history of our Solar System.

30. Review • Q: Why do planets and moons with atmospheres have less impact craters than those without atmospheres? • The atmosphere slows and burns smaller objects like meteorites, thus many do not reach the surface to create an impact.

31. Review • Bright streaks of light that result when rocky bodies burn up in the atmosphere are called ___________. • Frozen bodies made of ice, rock, and dust, sometimes called “dirty snowballs” are called _____________. • Small, rocky bodies that revolve around the sun are called ______________.

32. Review • Bright streaks of light that result when rocky bodies burn up in the atmosphere are called meteors. • Frozen bodies made of ice, rock, and dust, sometimes called “dirty snowballs” are called comets. • Small, rocky bodies that revolve around the sun are called asteroids.

33. Review • Q: Discus what could happen if the Earth experienced another large asteroid impact. How would it affect life on Earth? • Forests flattened for many miles • If asteroid landed in water, it would cause giant waves and landslides • Powerful Earthquakes

34. The devastation continues… • Poisonous gases and dust fills the atmosphere, blocks out the sun • Temperatures drop drastically • No photosynthesis = plants die = animals die • Some animals become extinct

35. Review • Q: Where is the Asteroid Belt? • Asteroid Belt is between Mars and Jupiter • Q: What is the Torino Scale? • A system used to rate the hazard level of an object moving toward Earth