Transcript Meteorites - Down2Earth

Meteorites
Meteors?
Meteoroid
in space
Meteor
in atmosphere
Meteorite
on Earth
Where do they come from?
Asteroid belt:
source of meteorites
How do we know?
Pribram 1959
Innisfree
1977
Asteroids can be really big
• Often smash into
each other
Mars
Meteorites are….
• Samples of planetesimals
• Samples of asteroids
• Oldest evidence of our solar system
• Up to 4.6 billion years old!
Types of
Meteorite
stony, iron or
stony-iron…
Stony
Iron
Stony-iron
Types of
Meteorite
Iron
• Iron meteorites
Stony
• Stony meteorites
– Chondrites
– Achondrites
Stony
Early Solar System
• A star exploded
• Bits of the cloud,
called a nebula,
began to stick
together
• Gravity pulled the
lumps together
• The lumps gathered
more and more
rocky dust
• They became the
planets
Chondrite
• From the oldest
asteroids
• Lumps ‘left over’
from when our
Solar System
formed!
Crusty Chondrite
• Can you see the
‘crust’ on this
meteorite?
• Friction melted the
meteorite’s surface
as it entered the
Earth’s atmosphere
Carbonaceous
chondrites
• Rare meteorites
• Most studied
• Formed in the solar
nebula 4.56 billion
yrs ago
• Contain elemental
carbon and amino
acids.
Differentiation
• Some planetesimals were large
• They differentiated into an iron-rich core and a
rocky mantle and crust
Iron Meteorite
• From the cores
of asteroids
• Dense ironnickel
• Same material
as core of Earth
Iron Meteorite
This stamp
commemorates
the fall of this
meteorite
• Has a ‘thumb
pressed’ surface
• Caused by
melting due to
friction in the
atmorpshere
Iron Meteorite
• Sliced to reveal
the inside
• Iron-nickel alloy
• Unique pattern of
crystals called
‘Widmanstätten’
Not
differentiated
Differentiated
Body
Crust
Achondrites
Achondrites
• From the crust of
a planetary
body
• Created by
meteorite
impacts
• Look like rocks
from Earth
Stony meteorite
(Achondrite)
• Some are from
the crusts of
asteroids
• Others are from
the Moon and
Mars
Stony meteorite
(Achondrite)
• This one is
actually from
the Asteroid
Vesta!
Pallasites
• Mixtures of iron-nickel
alloy and nonmetallic minerals
• Earth's core/mantle
Stony meteorites
(Achondrites)
• Look like rocks
from Earth
• Some are the
crusts of
asteroids
• Others are from
the Moon and
Mars
Tektites
• Earth rocks can be
melted on impact
• Molten droplets of
splashed rock fall
back to Earth
Moldavites
Source
crater
Moldavites
• A type of tektite
found in the Czech
Republic
• From the Ries crater
in Germany
• 15 million years old
How to spot a meteorite
• Magnetic
• No holes or bubbles
• Melted outside,
silver inside
• OR Dark crust, grey
inside
Impacts
Try the Impact
Calculator to see what
effect a meteorite
impact can have
http://down2earth.eu/
Impact_calculator