Top 10 Impacts and Near Misses

I just read a story on space.com today that reports asteroid 2011 AG5 has a chance to smash into Earth in the year 2040.  The asteroid was discovered in January of 2011 and was observed through September of that year.  The piece of space rock is 460 feet (140 meters) wide and could pass close enough to Earth to pose a threat to us on the surface.  While the odds of an impact are just 1 out of 625, any non-zero probability impact is closely monitored by the international astronomy community.  On its closest pass in 2023 2011 AG5 could shave by our planet at a distance of just 0.02 astronomical units (the distance between Earth and the sun), bringing it to a close shave of just 1.86 million miles.  The probability of impact is expected to decrease as scientists observe more orbits of the asteroid but it is still deserving of high levels of attention.

That got me thinking.  What are some of the closest shaves, or impacts, we’ve had with asteroids?  I’ve put together a list of ten asteroid collisions and near misses.  Enjoy and be horrified!

10) Comet Lexell passed within 0.0151 AU (1.4 million miles) of Earth on July 1, 1770 making it the closest comet pass by the Earth

9) Asteroid 2011 MD passed by Earth at an altitude of just 7,500 mi. which is roughly the diameter of the Earth, the rock was between 10 and 45 meters and it was estimated that it would have burned up in the atmosphere and only produced a few impacting fragments

8) A meteoroid named 2011 CQ1 flew by the Earth at a staggering distance of only 3,400 miles.  It was discovered on the same day as its closest pass to Earth.  The rock was only four feet wide so it posed absolutely no threat to life on Earth

7) A mere two months ago asteroid 2005 YU55, a 400 meter wide rock, passed within 201,700 mi. (0.85 lunar distances)

6) Meteoroid 2008 TC3 entered Earth’s atmosphere on October 7, 2008 and exploded over the Nubian Desert in Sudan.  It was the first object to be tracked as it approached the surface.

5) The event nicknamed “The Great Daylight 1972 Fireball” produced a meteoroid that passed a mere 35 miles from the Earth’s surface.  The meteoroid entered the atmosphere over Utah and skipped back out over Alberta, Canada.  The meteoroid was 57 meters wide  and could have detonated an explosion of up to 2 kilotons had it impacted the surface.

4) 1989 FC was a 300 meter wide asteroid that passed within 0.00457 AU of Earth.  While it never came within the orbital radius of the moon, it passed through the exact location of the Earth six hours earlier which drew many a sigh of relief.

3) The Barringer Crater, also known as Meteor Crater, is an impact crater in Arizona where a 50 meter meteoroid hit the planet approximately 500,000 years ago.  The crater is 0.737 miles across and 570 feet deep.

2) The Tunguska Event was an extremely powerful explosion that occurred over the region of Siberia in Russia in 1908.  It is believed that the explosion resulted from the airburst of a large meteoroid or comet just 3-6 miles above the surface.  The fragment never hit the ground but is still regarded as an impact because it released an explosion equivalent to 10-15 megatons of TNT that was 1,000 times more powerful than the atomic bomb dropped on Hiroshima.

1) Number one simply has to be the asteroid that formed the Chicxulub Crater on the Yucatan Peninsula in Mexico 65 million years ago.  The 10 kilometer wide object that hit the Earth there left an impact crater 120 miles in diameter and killed the dinosaurs and approximately 70% of life on Earth.   The impact packed a punch to the tune of 96 tetratons of TNT.  WOW.

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About Tim

My name is Tim Phelan. I am a nerd, amateur astronomer, sports nut, and follower of Jesus. I live in Baltimore, MD where the skies are oh so polluted with light. This is Ravens Country, Birdland, and the City that Reads, or whatever. Follow me on acrosstheuniverseinnotime.com and tphelan.wordpress.com

Posted on February 27, 2012, in Space and tagged , , , , . Bookmark the permalink. 1 Comment.

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