Asteroid 2012 EG5, 60 metres in diameter, will fly by the Earth tomorrow

Sunday, April 01, 2012

An asteroid is on the verge of flying past the Earth, another one that shares the characteristics of small asteroids that often make the news:

1) Only discovered in the past few days or weeks
2) Flyby distance similar to or less than that from the Earth to the moon.

Most of these asteroids (and apparently there were another two in the past month) are quite small, just a few metres in diameter. This one in relative terms is a monster at around 60 metres in diameter, the same as the length of a jet. Asteroids up to around 10 metres in diameter will break up in the atmosphere on the way down, but this one would cause a bit of damage. If you were standing 20 km away for example you might experience something like this:

The projectile begins to breakup at an altitude of 54000 meters = 177000 ft
The projectile bursts into a cloud of fragments at an altitude of 4700 meters = 15400 ft
The residual velocity of the projectile fragments after the burst is 4.77 km/s = 2.96 miles/s
The energy of the airburst is 4.52 x 1016 Joules = 1.08 x 101 MegaTons.
No crater is formed, although large fragments may strike the surface.

Air Blast:

The air blast will arrive approximately 1.04 minutes after impact.
Peak Overpressure: 18900 Pa = 0.189 bars = 2.69 psi
Max wind velocity: 41.4 m/s = 92.6 mph
Sound Intensity: 86 dB (Loud as heavy traffic)
Damage Description:

Glass windows will shatter.

About 30 percent of trees blown down; remainder have some branches and leaves blown off.

At even a slightly greater distance the effect is much smaller. Were an asteroid like this to hit the Earth it would most likely land in the ocean, the next most likely location would be uninhabited land. An asteroid of this size hitting the Earth is scary and unsettling (as it should be), but not catastrophic.

2012 EG5 will be passing by at a distance 0.6 times that to the moon, and a slightly slower than normal velocity of 8.54 km/s. You can take a look at and play around with its orbit here.


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