There are so many interesting tidbits about this past week's sky-show events. Here is a list of what caught my eye:
-- The 150-foot wide asteroid, known as DA14 passed so close to earth, missing by 17,200 miles, that out planet's gravity was expected to bend the asteroid's trajectory enough to put it in a slightly different orbit. The result will make future close encounters less likely.
-- DA14 was discovered last year by Spanish Astronomers and its trajectory carefully plotted. Asteroids are believed to be rocky debris left over from the formation of the solar system 4.6 billion years ago. Since dedicated surveys began some 15 years ago, astronomers have cataloged nearly 10,000 near-Earth asteroids, including roughly 1,000 big enough to cause global damage in a collision.
-- Asteroid collisions with earth are not uncommon, but most of the 80 to 100 tons of debris that hit the atmosphere every day is made up of small objects, burning up unseen at high altitude. Objects the size of basketballs impact daily, with car-size objects hitting every few weeks. Don Yeomans, an asteroid expert at NASA's Jet Propulsion Laboratory, says asteroids the size of DA14 could be expected to impact Earth once every 1,200 years on average. Yeomans believes asteroids large enough to trigger global catastrophe, like the six-mile-wide asteroid believed to have wiped out the dinosaurs, hit our planet every hundred million years or so.
-- The Russian meteor, said to be 50 feet across, lasted 30 seconds in our atmosphere before breaking apart some 12-15 miles above Earth's surface. The breaking apart was the violent explosion, releasing 300 kilotons of energy, that produced a shock wave shattering windows, collapsing walls and injuring more than 1,000 people, mainly from flying debris.
-- Paul Chodas, a scientist with NASA's Near-Earth Object program at the Jet Propulsion Laboratory in Pasadena, Calif. says the Russian meteor was the largest impact since 1908 when a 150-foot wide asteroid slammed into the atmosphere and detonated above Siberia. The so-called Tunguska event leveled millions of trees over more than 800 square miles.
(The above information is courtesy of William Harwood and Jim Todd, OMSI Director of Space and Industry.)
KGW Meteorologist Rod Hill