Transcript Meteorites - Ka`u Science

Meteorites
Fragments of the Solar System
• Dedicated to
Dr. Elbert King
– First director of
the Lunar
Receiving Lab
– Recovered a
lot of Allende!!
– Meteoriticist
Meteorites
• Meteoroids
– “small” rocks orbiting in space
• Meteors
– “rocks” entering the atmosphere and glowing
– Most are the size of a grain of sand
– Some are a lot bigger!!!
• Meteorites
– Rocks from space that have hit the Earth
Thunderstone of Ensisheim
• 1492
Thunderstone of Ensisheim
What’s left of it
• What Holbrook
supposedly
looked like
1946
• Famous
painting of the
Shikote-Alin
meteorite on a
USSR postage
stamp.
Meteorites
• Irons
• Stoney Irons
– Mesosiderites
– Pallasites
iron + nickel
MES
PAL
silicate + iron
iron + silicate (olivine)
• Stoney
– Chondrites
silicate + some iron (sometimes)
• Ordinary Chondrites H, L, LL
• Carbonaceous Chondrites C, CO, CV, CM, CK
• Others – Enstatite Chondrites E – Rumruti R
– Achondrites
• HED – from Vesta
• SNC – from Mars
• ALUN – from the Moon
Irons
• Cape York – “discovered” by Peary
from
Greenland
actually
discovered by
local Inuit
Irons
Irons
Irons
• Witmanstatten Patterns
• Gibeon
Irons
• Willamette
Irons
•
• Campo del Cielo
Hoba – 60 tons
Stony Irons
• Mesosiderites - MES
• Silicate based – with a lot of metal running
through it.
• NWA1879
Stoney Irons
• Another
mesosiderite
-MES
Stoney Irons
• Mesosiderite
Morristown
Stoney Iron
• Pallasites
• Iron based – with olivine crystals sprinkled
through
• Thought to
be from the
coremantle
boundary of
the parent
asteroid
Stoney Iron
Pallasite – lit from behind
Stoney - Chondrites
• Ordinary Chondrites
– H (High Metal) – L (Low Metal)
– LL (Very Low Metal)
• Inside (Brecciated)
Outside (Crusted)
Probably a L4-5 – this comes from NWA – Morocco
Chondrules / Chondrites
Stoney - Chondrites
• Carbonaceous chondrites
– Residue from the formation of the Solar
System – 4.5+ Billion Years old
Murcheson – CM2
Allende – CV3.2
Stoney - Achondrites
Meteorites from Asteroid 4 Vesta
• HED
• DAG 844
Howardite
Stoney - Achondrites
• HED
• Millbillillie
Eucrite
Stoney - Achondrites
• HED
• Johnstown
Diogenite
Stoney - Achondrites
Meteorites from Mars
• SNC
• Zagami
Shergottite
Stoney - Achondrites
• SNC
DAG 476
Dhofar 019
Stoney - Achondrites
Meteorites from the Moon
• ALUN
• DAG 400
How do we know they are from
Mars / the Moon / 4 Vesta??
• Mars: Viking 1 and 2 had soil and atmosphere
analyzers. The percentages of the elements and
isotopes are the same as the SNC meteorites –
and different from others!
• The Moon: Same story – except we have real
moon rocks to compare them to
• Vesta: Spectroscopy of Vesta indicates it is
made of HED materials, and no other asteroid is.
Recent studies show a great crater on Vesta
where some of these materials must have been
ejected from.
How to Study Meteorites
• What does it look like (big picture)
• What does it look like (microscope)
• What elements are in it (chemistry and
microprobe)
• What isotopic ratios are there (microprobe)
• Where did it come from (compare to
asteroids and planets)
• How did it fall (distribution)
Meteorites / Meteorwrongs
• Meteorites are not hot when they hit the earth!
• Almost all meteorites are magnetic!
• Almost all meteorites have some visible metal
(though sometimes only a little).
• Most meteorites are denser than local rocks.
• Meteorites don’t have holes/bubbles in them.
• For real analysis you have to take it to an expert
How to Study Meteorites
• Thin Sections –
The coolest way to look at meteorites is
in “thin section”. Take a thin slice of the
rock, glue it to a microscope slide and
grind/polish it until it is 30 micrometers
thick.
You can then look at it under a
“petrographic microscope” with crossed
polarizing filters. The colors tell you the
minerals!
Eucrite
Enstatite
Richfield LL3.7
Pultusk
• SNC
Some chondrules in thin section
Eucrite thin section
• Looks a lot like Kilauea basalts!
Apollo 17 Basalt
Apollo 12 Basalt
Impact!!!
• When a Big rock hits – 50
meters or more – it can make
a rather big hole in the
ground!!!!
Meteor Crater
Wolf Creek
Lake Manicoagan
Chixilub
Brent Crater
Pretoria “Saltpan”
Sudbury + Lake Wanapitei
Disclaimer
Aloha
I put together these power points for use in
my science classes.
You may use them in your classes.
Some images are public domain, some
are used under the fair-use provisions of
the copyright law, some are mine.
Copyright is retained by the owners!
Ted Brattstrom