METEORITES AND METEOR SHOWERS

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Dwain Claud Hamilton
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1 METEORITES AND METEOR SHOWERS

2 METEOROIDS, METEORS AND METEORITES Meteoroid: chunk of debris in the Solar System. Meteor: The visible path of a meteoroid that enters Earth's (or another body's) atmosphere. Meteorite: A meteoroid that reaches the ground and survives impact Meteor Shower: Many meteors appearing seconds or minutes apart. Comes from Greek meteōros, meaning "high in the air.

3 METEORITES - WHERE DO THEY COME FROM Each year aprox 80,000 tons of extraterrestrial matter, from microscopic dust particles to large rocks Some are identifiable pieces of the Moon, Mars, most are pieces of asteroids Meteorites were broken off their parent bodies 10 s to 100 s of million years ago Oldest meteorites (chondrites) contain bits of interstellar dust, tiny diamonds made in supernova explosions, organic molecules and amino acids (building blocks of life) Direct insight into solar system formation

4 METEORITE ALH84001 Discovered in Antarctica Dislodged from Mars about 16 million years ago Fell to Earth 13,000 years ago May contain fossil evidence that may indicate that primitive life existed on Mars more than 3.6 billion years ago.

5 WORLDWIDE FREQUENCY OF METEORITES AS FUNCTION OF SIZE Impact Frequency Size Frequency Destruction Area Pea Walnut Grapefruit Basketball 10/ hour 1/ hour 1/ 10 hours 1/ month 50 meters 1/ century New York City 1 kilometer 1/ 100,000 years Virginia 2 kilometers 1/ 500,000 years France 10 kilometers 1/ 100 million years World-Wide?

6 HOW METEORITES ARE FOUND Random finds lying on ground Fragments around meteor craters Follow glowing trail of meteor or fireball Systematic searches in Antarctica Special high-flying airplanes (for dust)

7 RANDOM FINDS Rare: a big meteorite in desert of Oman Pretty rare: random finds of smaller chunks

8 FRAGMENTS AROUND METEOR CRATERS Barringer Crater in Arizona kilometers across meters deep - formed about 49,000 years ago by the impact of a 50 meter nickel/iron meteorite traveling at a speed of 11 kilometers per second. Very large meteorites vaporize when they hit ground, form big craters Sometimes small pieces are found around crater

9 HOBA: THE WORLD'S LARGEST METEORITE The Hoba Meteorite is the largest known meteorite 66 ton - and the largest single mass of iron known on earth.

10 TYPES OF METEORITES There are 3 major types of meteorites: Stony (chondrites and achondrites) Iron Stony-iron

11 STONY METEORITES By far the largest number of meteorites fall into this class Similar in composition to the mantles and crusts of the terrestrial planets

12 Primarily iron and nickel From core of different asteroids IRON METEORITES

13 STONY-IRON METEORITES Crystals of rock mineral embedded in iron From boundary between core and mantle of large asteroids

14 IDENTIFY METEORITES Knowing what a meteorite looks like and what are its properties you can easily distinguish one from every other rock They are black and or dark brown, burnt from their speedy entrance into the atmosphere when their exterior melts. They have a solid like metal feel to them, as opposed to the "crumbly" feel of normal rocks. They all set off metal detectors due to their high metal content except for planetary originated meteorites such as those from the moon or mars. They are ferromagnetic, meaning a magnet will be attracted to them either lightly or strongly (although Martian and lunar meteorites are exceptions to this characteristic)

15 APPEARANCE A meteorite is heavier than an ordinary rock and will be attracted to a magnet. The condition of a meteorite can range from fresh to very weathered. Fresh meteorites have fusion crust, an aerodynamic shape and possibly thumbprints. Weathered meteorites may be more difficult to recognize due to the deterioration of its' meteoritic properties.

16 MAGNETIC FIELD 1. 99% of all meteorites are attracted to a strong magnet. (As are metal artifacts, slag and iron ore) Or if the object is small, hang it or the magnet from a string. This is used as a preliminary test and is recommended to new collectors. If your specimen does not pass this test it is probably NOT a meteorite!

17 STREAK TEST A stone meteorite, unless it is very heavily weathered will not normally leave a streak on a tile. If it leaves a black/gray streak the sample is likely magnetite, and if it leaves a vivid red to brown streak it is likely hematite.

18 METEOR SHOWERS Result when the Earth encounters commentary orbits The annual nature of meteor showers hints to the nature of the orbits of meteoroids.

19 Several hundred tons of meteoroids enter the Earth's atmosphere each day. Most of these are very small pieces (milligrams) that burn up quickly in the atmosphere and never reach the surface.

20 METEOR SHOWERS AND COMETS Occur on a regular schedule Some Meteor Showers Name Date of Maximum Meteors / Hour at Max Parent Quadrantids Jan Perseids Aug Comet 1862 III Orionids Oct Comet Halley Leonids Nov Comet P/Tempel-Tuttle Geminids Dec Phaethon

21 HOW TO SEE A METEOR SHOWER In order to see a meteor shower, go somewhere that has no (or very few) lights. It also makes a difference if the sky is absolutely clear and there is no moon.

22 PERSEID METEOR SHOWER AUGUST The Perseids are a summertime classic. The 2014 Perseid meteor shower should be at its prolific best from late night August 12 until dawn August 13! Great times to watch: after midnight and before dawn. The meteors tend to be few and far between at mid-evening, though this presents the best time of night to try to catch an earthgrazer an elongated, long-lasting meteor that travels horizontally across the sky. Earthgrazers are rare but most memorable if you re lucky enough to spot one.

23 WHERE TO LOOK? The meteors will radiate from the constellation Perseus, which rises in the evening in the northeast. They are typically fast and bright meteors. They frequently leave persistent trains.

24 THE ASTEROID AND THE DINOSAUR It has been proposed that 65 million years ago in what is now Yucatan the impact at a velocity of 11 km/second of a 10-kilometer wide asteroid threw huge amounts of matter into the atmosphere (in addition to local phenomena like generating 2000 foot waves that may have emptied the Gulf of Mexico!). This created months of darkness (interfering with photosynthesis) and much cooler temperatures globally, and the resulting harsh conditions led to the extinction of many species, including the last of the dinosaurs.

25 RESOURCES Russia Meteorite Dinosaur extinction asteroid Mars Perseids

A: Planets. Q: Which of the following objects would NOT be described as a small body: asteroids, meteoroids, comets, planets?

A: Planets. Q: Which of the following objects would NOT be described as a small body: asteroids, meteoroids, comets, planets? Q: Which of the following objects would NOT be described as a small body: asteroids, meteoroids, comets, planets? A: Planets Q: What can we learn by studying small bodies of the solar system? A: We can