Meteorites Austin Scott Meteoroid: A small particle (usually an asteroid or comet) orbiting the sun. Meteor: A meteoroid that is observed as it burns up in the Earth’s atmosphere (shooting star) Meteorite: A meteoroid that survives its passage through the Earth’s atmosphere and impacts the Earth’s surface. Lyrid shower april 16th – 26th

Sources Asteroids Chipped off from wear and tear (small collisions) Or pieces from interior of asteroid after catastrophic collision -different types of asteroids produce different types of meteorites Asteroids

Comparisons between infrared spectra of asteroids and meteorites. Reflection data for asteroids are circles with error bars. What we saw for each meteorite are given in the solid curves.

Meteorites can come from any body in space Meteorites can come from any body in space. Impact creates particles with high enough escape velocity to escape original body’s gravitation pull. -have found meteorites with exact same composition as the moon and mars Sources

Meteor Showers Lyrid shower april 16th – 26th Meteor showers are most often debris left in the orbits of comets or asteroids that happen to intersect Earth’s orbit. -dust particles that completely burn off in the earth’s atmosphere.

Types of Meteorites Stone aka stony aka stones – 96% of meteoroids that fall are stony achondrite – molten rock. Does not contain chondrules chondrite – have chondrules (spheres in the meteorite. Usually silicon dioxide, magnesium oxide, and iron II oxide. That cooled quickly from a molten state. either carbonaceous (has organic compounds that are volatile) water for instance or ordinary chondrite meteorites (few volatile (organic) materials. Therefore formed in warmer environments picture is actually from Allende Meteorite – will talk about later Iron – 3% found on earth no stone. at least 80% Iron, no more than 20% nickel, and traces of other elements. Stony-Iron – 1% found on earth mix of stone, iron and nickel. Formed at core and mantle of parent body. Gold and orange gemstones in iron/nickle. Look polished M-type asteroids would contain metals (iron/nickel) – Iron meteorites C-type asteroids would contain carbonaceous material – Stony chondrite meteorites Most of the meteorites we find on earth are iron. This is because we recognize iron and we if saw a stone metoerite, we would just think it was a bunch of rocks.

Allende Meteorite 1969 Largest carbonaceous meteorite ever found. Broke as it came to atmosphere, over 2 tons of the break were found. Determined to be 4.56 billion years old. (our sun is 4.57 billion years) concluded that meteorite is remnant of early solar nebula. What was most fascinating about it was it an under abundance of volatile elements. (H, He, C, N, O) which are close to a solar composition. But an overabundance of lithium. Concluded that meteorite condensed out of an inner portion of a nebula. (temp too high for those elements to be included in concentration) There was also calcium-aluminum-rich inclusions. These elements are not volatile at all.

Barringer’s Crater Arizona – Iron meteorite 50,000 years ago Meteorite was 50 m diameter Crater is 1.2 km wide and 200 m deep Hit somewhere between 12 and 20 km/s

Tunguska Event Siberia 1908. stony meteorite. evidence says that the meteorite exploded in atmosphere although we are still not certain. Leveled trees 15 km in every direction Knocked a man down 60 km away Could be heard from 1000 km Released 5x 10^17 Joules of energy

Dinosaurs? Found high level of iridium at time of Cretaceous-Tertiary boundary. (65.5 million years ago) Significance: rare rock found on earth’s surface because its soluble in molten iron. Also should have sunk towards core when it was created. This hints to some sort of stony asteroid. found tons in North America, major amount found on Yucatan peninsula. radioactive dating says same time period based on size of crater, energy during impact was 4x10^22 J

Difference in this meteorite is that debris would be scattered throughout the region (TN SC GA VA). Creating uninhabitable.

Shuttle Radar Topography Mission Major difference if it hit land besides water. water – vaporize large amount of water causing it to wash out airborne dust while the rest of the moisture would increase greenhouse effect. (heat being trapped) would cause for temp to rise and more and more water to evaporate. Temperatures could rise as much as 10 K. land – dust would cause more solar radiation to refelct into space, cooling the surface and doing the opposite as water. Either way – when it came into atmosphere, kinectic energy would go to heat energy and major fires would occur. Also, it would react with nitrogen in the air and cause nitrogen oxides and nitric acid – devastating acid rain would occur. Regardless, this meteorite changed the global environment dramatically.

Pennies from Heaven The Peekskill Meteorite http://aquarid.physics.uwo.ca/~pbrown/Videos/Peekskill/Peekskill_AnnMA.mpg

The End or the Beginning? Many carbonaceous chondrites have been found to contain many basic building blocks of life. 74 amino acids in one meteorite. 4 of 4 bases that crosslink the double helix of DNA (guanine, adenine, cytosine and thymine) 5th link that crosslinks RNA have been found in 1 meteorite Have also found fatty acids. This is all fundamental chemistry necessary to start the life process. So this is a possibility that extraterrestrial life, just like ours, can occur.

How will life on Earth end?

Meteorites Austin Scott Lyrid shower april 16th – 26th