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Dec 24 2015

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You can’t spell Santa without NASA

An early Christmas present to space and astronomy geeks:

NASA offers sneak peak at Christmas Eve asteroid. This is asteroid 2003 SD220:

It’s about 3600 feet long and passed about 6.8 million miles (about 28 lunar distances) from Earth today this morning (about 5:08am this morning Pacific time).

Plugging in amean diameter of 0.7 km, assuming a density of 2 g/cm^3 (2000 kg/m^3), and a velocity of 37.61908723 m/s (asteroid relative velocity plus Earth’s velocity) into the Earth Impact Effects Indicator (Which is my favorite asteroid-impact calculator), we get the following results:

In case you’re wondering what would have happened if 2003 SD220 actually hit Earth while you were in a in a boat 10 miles from the impact site in the ocean (assumed average depth 2.3 miles):here’s what the simulator says:

  • The average interval between impacts of this size somewhere on Earth during the last 4 billion years is 5,300,000 years
  • The projectile begins to breakup at an altitude of 78,300 meters = 257,000 ft. The projectile reaches the ground in a broken condition. The mass of projectile strikes the surface at velocity 36.9 km/s = 22.9 miles/s. The broken projectile fragments strike the ground in an ellipse of dimension 1.41 km by 0.997 km
  • The impact energy is 10,000 MegaTons. Hiroshima was 5.2 megatons.
  • It forms a crater on the ocean sea floor 4500 x 2000 feet wide and 962 feet deep.
  • The fireball appears 176 times larger than the Sun (and is 7.76 miles wide). Clothing, Newspaper, and Plywood, Trees and grass ignite, and much of the body suffers third degree burns.
  • If you somehow survived the fireball and didn’t sink, the air pressure wave would arrive 49 seconds after impact and would bring 4010 mph winds. The Sound Intensity would be 134 dB (Dangerously Loud).
  • A tsunami at least 1760 feet tall would hit you 90 seconds after the asteroid hit the water.

For a land impact, the crater would have been 8.28 miles in diameter and about 2120 feet deep. By comparison, Meteor Crater in Arizona is 0.737 miles in diameter and about 560 deep. It was caused by an impactor about 160 feet big.

So yeah…that would have been bad.

Permanent link to this article: http://www.newspaceraces.com/2015/12/24/you-cant-spell-santa-without-nasa/

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