Successfully reported this slideshow.
Your SlideShare is downloading. ×

12. Meteoroids and Comets (Trexia).pptx

Ad
Ad
Ad
Ad
Ad
Ad
Ad
Ad
Ad
Ad
Ad
Loading in …3
×

Check these out next

1 of 15 Ad

More Related Content

Recently uploaded (20)

Advertisement

12. Meteoroids and Comets (Trexia).pptx

  1. 1. Autida, Trexia B. Module 3 Lesson 19:
  2. 2. METEOROIDS • Meteoroids are small bodies that travel through space. Meteoroids are smaller than asteroids; most are smaller than the size of a pebble. Meteoroids have many sources. Most meteoroids come from asteroids that are broken apart by impacts with other asteroids. Other meteoroids come from the moon, from comets, and from the planet Mars.
  3. 3. When meteoroids enter the Earth's atmosphere they are called meteors. Popularly called a "shooting star" • If the meteors survive and strike the surface of the Earth they are called meteorites. • micrometeorites - "space dust"
  4. 4. Sporadic Meteor • These are the meteors that can be seen on any given night • They are not associated with any particular meteor shower • They come from random directions in the sky
  5. 5. A complete stone meteorite (L6 chondrite) recovered in McLennan County, Texas, only a few days after it fell to earth. This meteorite was part of the spectacular February 15, 2009 fireball filmed by a cameraman in Austin. Note the black fusion crust which is typical of freshly fallen meteorites, and the numerous flow lines— both created by the intense heat generated by the fireball.
  6. 6. Some Meteor Showers Name Date of Maximum Meteors / Hour at Max Parent Quadrantids Jan. 4 110 - Perseids Aug. 12 68 Comet 1862 III Orionids Oct. 21 30 Comet Halley Leonids Nov. 17 10 Comet P/Tempel-Tuttle Geminids Dec. 14 58 3200 Phaethon
  7. 7. COMET • Is an icy body that releases gas or dust. They are often compared to dirty snowballs, though recent research has led some scientist to call them snowy dirtballs. • Astronomers think comets are leftovers from the gas, dust, ice and rocks that initially formed the solar system about 4.6 billion years ago. • Comet contain - dust, ice, carbon dioxide, ammonia, methane, and more
  8. 8. Where do they come from? Comets come from two places: The Kuiper Belt and the Oort Cloud.
  9. 9. Comet Structure • Nucleus • 10 km “Dirty Snowball” • potato-shaped • 16 km to 8 km • irregular and full of craterlike pits • composed mainly of frozen water • Coma • Cloud of evaporated ices and ions • may be 100,000 km in diameter • Tail • Always points away from Sun • shaped by sunlight and solar wind
  10. 10. Types of Comets • Short-period comets −originate in Kuiper Belt beyond Neptune −Return to inner solar system every few years • Long-period comets −Originate in the Oort Cloud at the outer limits of the heliosphere −Return orbits over decades to thousands of years • Single Apparition
  11. 11. • Some people claim they have been hit by meteorites as they fall from the sky. This is extremely rare and many cases are unproven. • The first human we know to be hit by a meteorite is Ann Hodges who lived in Alabama, USA. In 1954, a meteorite crashed through her ceiling and struck her after bouncing off her radio. She was badly bruised and had a lucky escape as the meteorite weighed 4kg, about the same as a domestic cat. • The oldest report is from 1911 in Egypt when a dog was said to have been killed by a Martian meteorite. • The Barwell meteorite was the biggest to fall over Britain. It broke up and fell as a shower of stones over the Leicestershire village of Barwell on Christmas eve, 1965. The Barwell meteorite, the biggest meteorite to fall on Britain.
  12. 12. • Many people think that a comet's tail is always following behind it, but actually the coma, or tail, can either be behind the comet or in front of it. Which way the tail is pointing depends on where the Sun . That's right, the Sun's heat and radiation produce a wind called the Solar Wind, as a comet gets close to the Sun it begins to melt. The gas and dust that melt off are blown away from the Sun by the solar winds. So if a comet is traveling towards the Sun then the tail will follow behind, but if the comet is traveling away from the Sun the tail will be in front of the comet.
  13. 13. THANK YOU !!!

×