Free Republic

Two billion years ago a meteorite 10km in diameter hit the earth about 100km southwest of Johannesburg, creating an enormous impact crater. This area, near Vredefort in the Free State, is now known as the Vredefort Dome... The meteorite, larger than Table Mountain, caused a thousand-megaton blast of energy. The impact would have vaporised about 70 cubic kilometres of rock - and may have increased the earth's oxygen levels to a degree that made the development of multicellular life possible... The original crater, now eroded away, was probably 250 to 300 kilometres in diameter. It was larger than the Sudbury...

The destructive space rock was somewhere between 12.4 and 15.5 miles wide. The largest asteroid ever to hit Earth, which slammed into the planet around 2 billion years ago, may have been even more massive than scientists previously thought. Based on the size of the Vredefort crater, the enormous impact scar left by the gargantuan space rock in what is now South Africa, researchers recently estimated that the epic impactor could have been around twice as wide as the asteroid that wiped out the nonavian dinosaurs. The Vredefort crater, which is located around 75 miles (120 kilometers) southwest of Johannesburg,...

Incidents of these mystery booms are becoming more frequent Residents in Alabama were left baffled last week when a loud boom resounded across much of the state. The boom, nicknamed 'Bama Boom', has left experts stumped, with suggested causes ranging from supersonic aircrafts to meteors exploding in the atmosphere. This isn't the first time that the mysterious sound has been heard, and incidents are becoming more frequent according to some reports.  This year alone, similar noises have been reported 64 times this year, in locations including Michigan, Lapland, St Ives, Swansea and Yorkshire. ... The Birmingham National Weather Service tweeted:...

Supervolcanoes, massive eruptions with potential global consequences, appear not to follow the conventional volcano mechanics of internal pressure building until the volcano blows. Instead, a new study finds, such massive magma chambers might erupt when the roof above them cracks or collapses. Knowledge of triggering mechanisms is crucial for monitoring supervolcano systems, including ones that lie beneath Yellowstone National Park and Long Valley, California, according to the study led by Patricia Gregg, University of Illinois professor of geology, in collaboration with professor Eric Grosfils of Pomona College and professor Shan de Silva of Oregon State University. The study was published...

COLORADO SUPERBOLIDE: Last night, Dec. 6th at 1:06 a.m. MST, a meteor of stunning brightness lit up the skies of Colorado. Astronomer Chris Peterson photographed the event using a dedicated all-sky meteor camera in the town of Guffey, near Colorado Springs: Video:http://spaceweather.com/swpod2008/06dec08/Chris-Peterson1_strip.gif?PHPSESSID=s7mlc3ga8e6isub9bapbfqjkp2 "In seven years of operation, this is the brightest fireball I've ever recorded," says Peterson. "I estimate the terminal explosion at magnitude -18, more than 100 times brighter than a full Moon." Fireballs this bright belong to a rare category of meteors called superbolides. They are caused by small asteroids measuring a few to 10 meters in...