METEORITES AND METEOR SHOWERS

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”.

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

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.

WORLDWIDE FREQUENCY OF METEORITES AS FUNCTION OF SIZE

Impact Frequency

Size Frequency Destruction Area

Pea 10/ hour

Walnut 1/ hour

Grapefruit 1/ 10 hours

Basketball 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?

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)

RANDOM “FINDS”

• Rare: a big meteorite in desert of Oman

• Pretty rare: random “finds” of smaller chunks

FRAGMENTS AROUND METEOR CRATERS

• Very large meteorites vaporize when they hit ground, form big craters

• Sometimes small pieces are found around crater

Barringer Crater in Arizona

- 1.2 kilometers across

- 200 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.

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.

TYPES OF METEORITES• There are 3 major types of meteorites:

• Stony (chondrites and achondrites)

• Iron

• Stony-iron

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

IRON METEORITESPrimarily iron and nickel

From core of different asteroids

STONY-IRON METEORITES

• Crystals of rock mineral embedded in iron

• From boundary between core and mantle of large asteroids

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)

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.

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!

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.

• Result when the Earth encounters commentary orbits

• The annual nature of meteor showers hints to the nature of the orbits of meteoroids.

METEOR SHOWERS

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.

METEOR SHOWERS AND COMETS• Occur on a regular schedule

Some Meteor Showers

Name Date ofMaximum

Meteors / Hourat 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

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.

PERSEID METEOR SHOWERAUGUST 12-13 2014

• 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.

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.

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.

RESOURCEShttps://www.youtube.com/watch?v=Bhlbntm3-tE

https://www.youtube.com/watch?v=qdTMYcUsuuw

https://www.youtube.com/watch?v=oCmilpor7Pw

https://www.youtube.com/watch?v=J08PuCQChU4

Russia Meteorite

https://www.youtube.com/watch?v=dpmXyJrs7iU

https://www.youtube.com/watch?v=SMnZr5DDRlA

Dinosaur extinction

https://www.youtube.com/watch?v=Y8Ij9xboreA

https://www.youtube.com/watch?v=dBvotWfR3j4&index=4&list=PLxvQrKE6To445NZUltYBKRlK79LmCBg9X

asteroid

https://www.youtube.com/watch?v=4OJjrr95Krc

Mars

https://www.youtube.com/watch?v=NOXjbizhtVA

Perseids

https://www.youtube.com/watch?v=-LnLlJrIA0w

http://www.meetup.com/astronomy-131/