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Stargazer: Arizona’s Meteor Crater
Wednesday, May 6, 2009 • Posted May 5, 2009

Arizona is known as “the Grand Canyon state” and with good reason. The awe-inspiring beauty of the famous Grand Canyon is matched only by its unbelievable enormity. For millions of years the Colorado River has been carving the mile-deep canyon, and it’s not finished yet.

But the state has another huge hole in the ground which, while not as large and well-known, is impressive in its own right — and it was blasted out in a matter of seconds. Some 50,000 years ago Earth was impacted by a large piece of solar system debris, resulting in what is popularly called Meteor Crater.

A 150-foot in diameter chunk of iron, probably from the asteroid belt, weighing several hundred thousand tons and traveling 27,000-40,000 mph (estimates vary) struck the northern Arizona desert with the explosive force of 20 million tons of TNT. In less than 10 seconds, 175 million tons of earth — rock, soil, and sand — were excavated, leaving a gaping crater more than 700 feet deep, 4,000 feet across, and 2 1/2 miles around.

Over the years, erosion has partially filled the crater — also called Barringer Crater and Canyon Diablo Crater — so that it is now only 550 feet deep. Still, that’s deep enough that if a 55-story building, or the Washington Monument, was placed on the crater’s floor, the building’s or monument’s top would be at ground-level.

Geologist Gene Shoemaker estimated that an event comparable to the Meteor Crater impact can be expected, on average, every 50,000 years, so we are due. What if one were to hit now? Being much smaller than the comet or asteroid impact 65 million years ago believed to have caused the extinction of many species, including the dinosaurs, it would not mean the end of our species or any other.

But such an impact in or near a populated area would almost certainly produce staggering destruction and death to many thousands if not millions. Or imagine the tsunami resulting from an ocean impact. In my view, government programs to identify and track near-Earth objects and formulate plans for averting such impacts should not be regarded as futuristic science fiction or “wasteful government spending.” Indeed, only an ignorant or foolish species would ignore such a threat.

• Sky Calendar.

  • May 6 Wed. morning: The Eta Aquarid meteor shower peaks but the Moon doesn’t set until 2 hours before sunrise.
  • 8 Fri.: The full Moon is called Milk Moon and Planting Moon.
  • 17 Sun. morning: The 3rd quarter Moon is to the left of Jupiter.
  • 21 Thu. morning: The crescent Moon is to the left of Venus and above much fainter Mars low in the east at dawn.

• Naked-eye Planets. (The Sun, Moon, and planets rise in the east and set in the west due to Earth’s west-to-east rotation on its axis.) Evening: Saturn is high in the south with Mercury low in the west northwest at dusk. Morning: Jupiter is the brightest object in the southeast with “morning star” Venus low in the east and much fainter Mars to Venus’ lower right at dawn.

Stargazer appears every other week. Paul Derrick is an amateur astronomer who lives in Waco. Contact him at 918 N. 30th, Waco, 76707, (254) 753-6920 or paulderrick waco@aol.com. See the Stargazer Web site at stargazerpaul.com.

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