Meteors and Meteorites. Voorhees High School Astronomy Club Nick Meligari Mrs. Bellows. 2010. Terms about Meteors. Meteoroid – any particle in space from the size of a sand grain to boulder Meteor – Flash of light from a meteoroid that burns in the Earth’s atmosphere. Terms Cont.
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Meteors and Meteorites Voorhees High School Astronomy Club Nick Meligari Mrs. Bellows 2010
Terms about Meteors • Meteoroid – any particle in space from the size of a sand grain to boulder • Meteor – Flash of light from a meteoroid that burns in the Earth’s atmosphere.
Terms Cont. • Meteorite – A meteoroid that lands on Earth. • Bolide – Large meteor; seen in broad daylight, sometimes explodes (can knock down entire forests)
Why Meteors Glow? • Front side begins to melt and release chemicals • These substance glow when they are heated • Friction with atmosphere due to speed: 160,000 mph or 20-40 km / s (a rifle bullet travels .7km/s)
Zenith Hourly Rate • ZHR is a count of how many meteors you can see in an hour under the best conditions for a meteor shower: • Zenith (darkest part of sky, 6.5 limiting mag) • After midnight (when Earth turns into the meteoroids) • Maximum shower debris period
Classifying Meteorites • They’re classified according to distinguishing features and of what they are made (elements). • Example: iron meteorites, have a main make up of iron (Fe) and nickel (Ni)
Composition of Iron Meteorite • Iron 91%Nickel 8.5%Cobalt 0.6%
Widmanstatten Lines • Crystals of iron and nickel show up when meteorite is cut and acid-polished. • Form under extreme pressure and long cooling in space
Composition of Stony Meteorite • Oxygen 36%Iron 26%Silicon 18%Magnesium 14%Aluminum 1.5%Nickel 1.4%Calcium 1.3% • Like Earth’s mantle
Composition of Stoney Chondrite Meteorites (80%) • Mainly carbon; contain chondrules (spheres) • Most primitive objects in the solar system • Can supply us with materials from beyond our solar system • Weather very easily
Achrondite • Has gone through melting • Magma of parent body • Stony meteorite without chondrules • The cube is 1 cm • The meteorite sells for $5,000
Tektites • Blobs of molten iron & silica that cooled rapidly • Fragments from a major impact recaptured by Earth • Origin can be Earth, Moon or Io • Four major tektite fields
Iridium • Most corrosive resistant metal known • A heavier element, rare on the Earth’s crust (.03 ppb), but common in meteorites (500 ppb). • A thin layer (3 ppb) of Iridium lies at the K-T boundary, dating back 65 million years. • Best hypothesis is an ash cloud containing iridium dust covered the planet. This is believed to have been from an impact that caused the dinosaur extinction.
Coesite • Coesite is a form of shocked quartz (SiO2) • The pressure and temperature required are by meteorite impact or atomic bomb explosion. • It helps identify a crater’s origin. • In the image, coesite is the entire dark blue area
Barringer Meteor Crater • Winslow, Arizona • Hit by a 70,000 ton object • 60 meters in diameter • Traveling at 40,000mph
Barringer Crater Statistics • The crater is 1,219 meters wide • The force of the impact was 750 times more powerful than that of the Hiroshima atomic bomb
AMNH’s Largest Displayed Meteorite • Named “Ahnighito” by the Eskimos • Discovered in Greenland, and brought to the U.S. by explorer Robert Peary • Mainly composed of Iron
“Ahnighito” • Ahnighito was used by the Inuits to create tools, knives, etc • Ahnighito weighs a WHOPPING 34 – tons
The largest meteorite 65-ton Hoba Meteorite Still in ground, Namibia, Africa Fell 80,000 years ago
Gibeon Meteorite • An estimated 12,000 years ago an Iron Nickel meteorite hit Africa. • It left a trail of shrapnel and debris 70 miles wide and 230 miles long
Gibeon Cont. • The meteorite was created in an atmosphere with temperatures excess of 2,500 degrees and 0 gravity, and cooled extremely slowly over millions of years, forming crystals of Fe and Ni.
Zagami Fall • Largest meteor fall: 40 lbs, 1962 • All 14 Meteors found came from Mars, total 175 lbs. • The gas trapped in the pockets matched the composition of the Mars atmosphere as determined by Viking missions in the 1970’s.
Chicxulub Meteor Crater • Located on the Yucatan Peninsula • The meteorite or asteroid was the size of a small city, approx. 15 – 20 miles in diameter
Chicxulub: the KT Event • The impact sent tsunamis, and earthquakes around the globe • Global dust storm; ash obscured Sun for centuries, global cooling • Thin layer of iridium all over the world
Chicxulub • Believed to be the cause of the dinosaur extinction, through either a global firestorm or major global environmental changes (global dust blocking Sun)
Sylacauga Meteorite • 1954 – A meteorite crashed through the roof of Mrs. E. Hewlett Hodges in Sylacauga, Alabama. It bounced throughout her home and hit her in the leg
Wethersfield Meteorite • 1982 – Wethersfield, CT The Donahues were home when a 6lb meteorite crashed into their home and destroyed furniture in a near room. They donated the rock to The New Haven Museum
Peekskill Meteorite • 1992 – Peekskill, NY an 8lb meteorite hit a Chevy Malibu owned by Michelle Knapp. She sold the car and meteorite for $69,000. The car now tours the country.
Asteroid 2008 TC3 had diamond dust! This December 2008 photo, released by NASA, shows a black chunk of rock found in the Sudan desert, the first time astronomers have tracked an asteroid from space, toward Earth, into the atmosphere and down on the ground as a meteorite; the fireball fell 10/2008.
Perseid Meteor Shower • Source of the shower is from the Comet Swift-Tuttle • Come every year, late July through August • Swift-Tuttle is nowhere near Earth, we pass through its tail
Perseid Cont. • The meteors from Swift-Tuttle hit Earth traveling at 132,000 mph • Perseid meteors appear to fly out from the direction of the constellation Perseus
Leonid Meteor Storm • Greatest Meteor Storm, occurred 166 years ago on Nov. 13, 1833 • Shower went on for over 4 hours with thousands of meteors falling every minute
Leonids Cont. • In 1998 the Leonids, (appear to be coming from the constellation Leo) fell as a storm. • There were approx. 1 meteor per second, for some locations on Nov. 18, 2001, another year for a storm.
Find a meteorite? • Send a brief letter describing your sample to: Director of the Center for Meteorite Studies Arizona State University Main Campus PO Box 872504 Tempe, AZ 85287-2504 This is a free service; if you send in your sample for evaluation, and it is a meteorite you will have an offer for purchase before it is returned.