Transcript mass extinction kalei and shae

Mass extinction and
comets
By: Shae Otsuka and Kalei Kahookele
What is Mass
extinction?
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An extinction event (also known as: mass extinction; extinction-level event (ELE), or biotic
crisis) is a sharp decrease in the diversity and abundance of macroscopic life. They occur
when the rate of extinction increases with respect to the rate of speciation. Because the
majority of diversity and biomass on Earth is microbial, and thus difficult to measure, recorded
extinction events affect the easily observed, biologically complex component of the biosphere
rather than the total diversity and abundance of life
Causes of mass
extinction
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Impact from space- Most scientist agreed that an asteroid collision 65 million
years ago brought an end to the age of dinosaurs, but there is uncertainty about
how many other extinctions might have resulted from asteroid or comet collisions
with Earth.
Super volcanoes- Super volcanoes are giant eruptions of lava that can last a
million years and cover a million km2 of the surface. Supervolcanoes ooze lava
from long fractures in the Earth's crust and give off trillions of tonnes of carbon
dioxide, sulphur dioxide, fluorine and chlorine
Gamma-ray bursts- Gamma-ray bursts are the most violent and energetic
explosions in the universe, caused when a star collapses to form a black hole.
The Permian-Triassic
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The Permian–Triassic (P–Tr) extinction event, informally known as the Great Dying, was an
extinction event that occurred 251.4 million years ago, forming the boundary between the
Permian and Triassic geologic periods also known to be one of the worst extinctions.
It was the Earth's most severe extinction event, with up to 96% of all marine species and 70%
of terrestrial vertebrate species becoming extinct It is the only known mass extinction of
insects.
Researchers have variously suggested that there were from one to three distinct pulses, or
phases, of extinction. There are several proposed mechanisms for the extinctions; the earlier
phase was likely due to gradual environmental change, while the latter phase has been
argued to be due to a catastrophic event.
What is a comet?
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A comet is an icy small Solar System body that, when close enough to the Sun, displays a
visible coma (a thin, fuzzy, temporary atmosphere) and sometimes also a tail. These
phenomena are both due to the effects of solar radiation and the solar wind upon the nucleus
of the comet
Facts about Comets
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Comets have a wide range of orbital periods, ranging from a few years to hundreds of
thousands of years. Short-period comets originate in the Kuiper belt, or its associated
scattered disc,[1] which lie beyond the orbit of Neptune
Comet nuclei are known to range from about 100 meters to more than 40 kilometres across.
They are composed of rock, dust, water ice, and frozen gases such as carbon monoxide,
carbon dioxide, methane and ammonia
In the outer solar system, comets remain frozen and are extremely difficult or impossible to
detect from Earth due to their small size.
Facts cont.
1.Comet orbits are elliptical. It brings them close to the sun and takes them far away.
2.Short period comets orbit the Sun every 20 years or less. Long period comets orbit the Sun every
200 years or longer. Those comets with orbits in between are called Halley-type comets.
3.Comets have three parts: the nucleus, the coma and the tails. The nucleus is the solid center
component made of ice, gas and rocky debris. The coma is the gas and dust atmosphere around
the nucleus, which results when heat from the Sun warms the surface of the nucleus so that gas
and dust spew forth in all directions and are driven from the comet's surface. The tails are formed
when energy from the Sun turns the coma so that it flows around the nucleus and forms a fanned
out tail behind it extending millions of miles through space.
largest comet to hit
earth
• 65 million years ago
• Cretaceous tertiary extinction was more
than 10km in diameter
• every ten million years, there was a
large impact
Eugene Merle
Shoemaker
• proved that meteor
impacts affected
earth
• studied other solid
bodies in the solar
system and their
impact sites
Impact Crater in
Arizona
• The Barringer
Crater is 50,000
years old caused
from a large impact
works cited
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Come, Joey. "Comet and Asteriod Risks to Earth." Dhushara. Apr.-May 2002. Web. 19 Apr. 2011.
<http://www.dhushara.com/book/future/comet.htm>.
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Georgetown, Daniel. "Dinosaur Floor: Giant Impact." COTF. 30 July 1996. Web. 19 Apr. 2011.
<http://www.cotf.edu/ete/modules/msese/dinosaurflr/ecraters.html>.
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Kronk, Gary. "Comet Hysteria and the Millennium." Cometography. 5 Apr. 1990. Web. 19 Apr. 2011.
<http://cometography.com/hysteria.html>.
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Middleton, George M. "Earth's Biggest Asteroid Impact Ever -Did It Occur in Antarctica? NASA Gravity Maps
Point to "Yes"" The Daily Galaxy - Great Discoveries Channel -Your Daily Dose of Awe: Science, Space, Tech. 17
Sept. 1999. Web. 19 Apr. 2011. http://www.dailygalaxy.com/my_weblog/2010/03/did-the-planets-most-massiveasteroid-impact-ever-occur-in-antarctica-nasa-gravity-maps-point-to-yes.html
video
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http://www.youtube.com/watch?v=LlF8APEkh-E