1. Meteorites
26 October 2015

3. Chondrite

4. Achondrite

5. Martian

6. Chixulub, Yucatan penninsula, Mexico
Gravity map of buried structure
180 miles across; 65 millions years old
Identified in early 1990s with seismic data, after 10 year ‘search’

7. Tunguska, Siberia, June 30, 1908
Black and white photos taken during field expedition in 1927; color photo taken in 1990

8. Jackson Hole Fireball, August 10, 1972

9. Potentially Hazardous Asteroid Threat Size-frequency diagram for impacting objects
~100 tons of meteroritic dust falls each day
50 m impactor once per 1000 yr (local effects)
500 m impactor once per million years (regional effects)
5 km. impactor once per 100 million years (global effects)

10. Hoba Iron 3m x 2m x 1m; 60+ tons Found 1920, Namibia
No crater, classified ataxite

11. Ordinary Chondrites (S Asteroids?)

12. Three Views of Vesta Hubble image, model and color-shaded topography
Largest member of V class of asteroids (vestoids)
Spectral variations consistent with HEDs

13. What were the processes and products in the early Solar System (Meteoritics, 2004)
Impact features on all planetary surfaces; planets formed by accretion of planetesimals from a turbulent solar nebula
Much mixing of components; completed in 5-10 million years
‘Residual’ debris forms asteroid belt; Kuiper belt, Oort cloud

14. Meteor showers Time exposure image, tracking stellar motion
Stars stay still, meteorites make trails

15. The Peekskill (NY) Fireball

16. P Jenniskens et al. Nature 458, 485-488 (2009)
Macroscopic features of the Almahata Sitta meteorite.
P Jenniskens et al. Nature 458, (2009)

17. Chondrites Rocky, inhomogeneous, contain round “chondrules”
Microscope image

18. Iron meteorites: from core of differentiated asteroids

19. Stony-Iron meteorites - the prettiest
Crystals of olivene (a rock mineral) embedded in iron
From boundary between core and mantle of large asteroids?

23. The main points: Meteorites
Each year the Earth sweeps up ~80,000 tons of extraterrestrial matter
Some are identifiable pieces of the Moon, Mars, or Vesta; most are pieces of asteroids
Meteorites were broken off their parent bodies 10’s to 100’s of million years ago (recently compared to age of Solar System)
Oldest meteorites (chondrites) contain interstellar dust, tiny diamonds made in supernova explosions, organic molecules and amino acids (building blocks of life)
Direct insight into pre-solar system matter, solar system formation