13 Impacts

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13 - Impacts Extinctions
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The Important Rules of Impacts RULE 1 Impacts
Happen RULE 2 There are Consequences to Rule 1
Barringer Crater, near Winslow, Arizona (just
east of Flagstaff) - 1 mile wide blemish
(There are also near-misses - 1972 over Tetons)
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RULE 3 The History of the Solar System is
Written on the Face of the Moon
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Energy of Impacts
Rate of Impacts
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The Tunguska Event On the morning of June 30,
1908, a brilliant fireball appeared in the
morning skies of Siberia, and exploded at an
altitude of about 6 km. At a distance of 60 km
from ground zero people were knocked to the
ground. Those within 30 km were thrown into the
air (and one person was killed as a result). No
impactor body was ever found. 3-5 Megaton
airburst a comet or asteroid. No UFOs or black
holes required
Aerial photo (above) and close-up (below) of
flattened trees
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Comet Shoemaker-Levy 9 (SL9)
Discovered by Eugene Carolyn Shoemaker and
David Levy on March 24, 1993 using the 18-inch
Schmidt telescope at Mt. Palomar,
California. Weird appearance due to it being a
string of fragments
Image by Jim Scotti, Spacewatch Telescope at Kitt
Peak, Arizona
Hubble WFPC2 image of the SL9 fragments, with
labels assigned them
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Set for Impact with Jupiter
Montage of images of Jupiter SL9
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Great Comet Crash - July 1994
The impacts were particularly impressive in the
infrared, as shown in this image from the Calar
Alto Observatory
scars of the impacts as big as the Earth
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Impacts Extinctions
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Cretaceous-Tertiary (K-T) Boundary
Found world-wide Ir content - in 1980 Luis
Walter Alvarez suggest it was due to an impacting
asteroid Also - shocked quartz
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Reminder - also affected other forms (example -
brachiopods)
Though hotly debated in the 1980s later,
impact hypothesis still favored for much of the
K-T extinction event. So where is the smoking
gun?
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Yucatan, Mexico!
Gravimetric map cenotes
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Shocked quarts (above) tectites (below)
There are current drilling projects to
investigate more
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For a nice site on the subject, see the one by
Ralph Taggart at MSU
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Many Existing Near Earth Object (NEO) Programs in
US - discover track potentially hazardous
asteroids comets
Lincoln Near-Earth Asteroid Research (LINEAR) -
MIT Air Force - telescopes near Socorro NM Near
Earth Asteroid Tracking (NEAT) - Air Force JPL
- telescopes at Haleakala, Maui, and Mt. Palomar,
CA Spacewatch - University of AZ - telescope on
Kitt Peak near Tucson AZ Lowell Observatory
Near-Earth Object Search (LONEOS) - Flagstaff
AZ Catalina Sky Surveys - Catalina Station Mt.
Lemmon Station (near Tucson) Siding Springs
Observatory, Australia
C/2002 T7 LINEAR
C/2001 Q4 NEAT
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Schwassmann-Wachmann 3
Despite claims that crop circles made by aliens
were a warning about the destruction of the Earth
by SW3, no impact occurred.