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
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.
• Very large meteorites vaporize when they hit ground,
form big craters
• Sometimes small pieces are found around crater
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 METEORITES
Primarily 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.
METEOR SHOWERS
• Result when the Earth encounters commentary
orbits
• The annual nature of meteor showers hints to the
nature of the orbits of meteoroids.
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 of
Meteors / Hour
Maximum
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
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 SHOWER
AUGUST 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.
https://www.youtube.com/watch?v=Bhlbntm3-tE
https://www.youtube.com/watch?v=qdTMYcUsuuw
https://www.youtube.com/watch?v=oCmilpor7Pw
RESOURCES
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/