Chapter 9
Notes
Have we ever
witnessed a major impact?
Comet SL9 caused a string of violent impacts on Jupiter in
1994, reminding us that catstrophic collisions still happen.
Tidal forces tore it apart during a previous encounter with
Jupiter.
Fossil record shows occasional large dips in the diversity of
species: mass extinctions
The most recent was 65 million years ago, ending the reign of
the dinosaurs.
Iridium is very rare in earth surface rocks but is often
found in meteorites.
Dinosaur fossils all lie below this layer.
No dinosaur fossils in upper rock layers.
Thin layer containing the rare element iridium.
Dinosaur fossils in lower rock layers.
A meteorite 10 km in size would send large amounts of debris
into the atmosphere.
Debris would reduce the amount of sunlight reaching earth’s
surface.
The resulting climate change may have caused mass extinction.
Size of crater suggests impacting object was 10km in
diameter.
The gravity
of a jovian planet (especially Jupiter) can redirect a comet.
Jupiter has
directed some comets toward earth but has ejected many more into the Oort
cloud.
1 comment:
Congratulations, always on time!
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