101. MIAC - Impact Craters Map of crater locations in Canada, crater images, explanation and images of rock altered by impact. http://miac.uqac.ca/MIAC/impact.htm

MIAC Impact Craters on Earth Canadian impact structures. The map shows the locations of meteorite impact structures recognised in Canada. An updated list of Canadian impact sites is included in the annual Observer's Handbook of the Royal Astronomical Society of Canada. (Courtesy Richard Grieve, Geological Survey of Canada) Manicouagan Crater The Manicouagan crater lies in northern Quebec, Canada (Lat 51 23N, Long 68 42W). It is one of the largest known, with a diameter of about 100 km. The crater is a multiple-ring structure, but the feature that shows up best in this Landsat satellite photo is the inner ring, which is occupied by a lake (Manicouagan 5 reservoir) with an outer diameter of about 70 km. The impact occurred 214 million years ago. The asteroid probably had a diameter of about 5 km. It may have produced a mass extinction similar to that at the end of the Cretaceous period. (Courtesy NASA) A series of cartoons show how this crater was formed Pingualuit Crater (Nouveau / New Quebec, Chubb) Wolf Creek Crater, Western Australia

102. APOD: 2000 February 26 - Impact: 65 Million Years Ago Computer rendering of Chicxulub crater, from gravity and magnetic field data. http://antwrp.gsfc.nasa.gov/apod/ap000226.html

Astronomy Picture of the Day Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer. 2000 February 26 Impact: 65 Million Years Ago Credit: courtesy V.L. Sharpton, LPI Explanation: What killed the dinosaurs? Their sudden disappearance 65 million years ago, along with about 70 percent of all species then living on Earth, is known as the K-T event (Cretaceous-Tertiary Mass Extinction event). Geologists and paleontologists often entertain the idea that a large asteroid or comet impacting the Earth was the culprit. In such a cosmic catastrophe, the good(!) news would be that the impact would generate firestorms, tidal waves, earthquakes, and hurricane winds. As for the bad news ... debris thrown into the atmosphere would have a serious global environmental consequences, creating extended periods of darkness, low temperatures, and acid rains - resulting in a planet-wide extinction event. In 1990, dramatic support for this theory came from cosmochemist Alan Hildebrand's revelation of a 65 million year old, 112 mile wide ring structure

103. APOD: 2000 December 13 - Manicouagan Impact Crater On Earth Image taken from space shuttle Columbia in 1983. http://antwrp.gsfc.nasa.gov/apod/ap001213.html

Astronomy Picture of the Day Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer. 2000 December 13 Manicouagan Impact Crater on Earth Credit: STS-9 Crew NASA Explanation: The Manicouagan Crater in northern Canada is one of the oldest impact craters known. Formed during a surely tremendous impact about 200 million years ago, the present day terrain supports a 70-kilometer diameter hydroelectric reservoir in the telltale form of an annular lake . The crater itself has been worn away by the passing of glaciers and other erosional processes. Still, the hard rock at the impact site has preserved much of the complex impact structure and so allows scientists a leading case to help understand large impact features on Earth and other Solar System bodies. Also visible above is the vertical fin of the Space Shuttle Columbia from which the picture was taken in 1983. Tomorrow's picture: ISS Above Archive Index Search ... USRA NASA Technical Rep.:

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