Friday, January 3, 2014

An Update to - it's "virtually certain" that 2014 AA hit Earth.

Geraldo was wondering if 2014 AA might have others following and the following is my comment.
- LRK -

Let's hope not.  The pictures taken that show this one, don't seem to show others with it.  The sounds made from the burn up over the Atlantic had a couple of locations but very weak.
Discovery of asteroid 2014 AA

A sequence of four images, taken roughly 11 minutes apart, reveals the movement of asteroid 2014 AA when it was discovered in northern Orion early on January 1st (Universal Time). The 19th-magnitude object struck Earth 25 hours later.
Catalina Sky Survey / NASA

It was New Year's Eve, but that didn't stop observer Richard Kowalski from scanning the sky for near-Earth objects (NEOs).

He hadn't been using the 60-inch telescope on Arizona's Mount Lemmon for long when he noticed a 19th-magnitude blip skimming through northern Orion in a seven-image series begun at 5:16 p.m. (1:16 Universal Time on January 1st). After confirming that it was a new find, Kowalski dutifully submitted positions and times to the IAU's Minor Planet Center. Then he went back to the night's observing run.
As announced by the MPC earlier today, it's "virtually certain" that 2014 AA hit Earth. According to calculations by dynamicist Stephen Chesley (Jet Propulsion Labo­ra­tory), the impact occurred over the Atlantic Ocean somewhere between Central America to East Africa. Chesley's "best-fit" collision is just off the coast of West Africa at roughly 2:30 Universal Time this morning.
More precision has come from an analysis of infrasound data by Peter Brown (University of Western Ontario). Infrasound is extremely low-frequency acoustic energy (20 hertz or less) created, for example, during energetic explosions. A global network of detectors, maintained by the Comprehensive Nuclear-Test-Ban Treaty Organization, can pinpoint the location and energy of any powerful detonation — including airbursts from meteoric blasts.

Pinpointing 2014 AA's impact
The overlap of the white curves, from three marginal infrasound detections, shows where the small asteroid 2014 AA likely hit. However, this preliminary plot does not take winds into account, which might shift the true impact point somewhat further east.
Peter Brown
According to Brown, 2014 AA triggered very weak detections at three infrasound stations. His triangulation from those records, shown in the graphic at right, indicates that the space rock slammed into the atmosphere near 40° west, 12° north. That location, about 1,900 miles (3,000 km) east of Caracas, Venezuela, is far from any landmass.

"The energy is very hard to estimate with much accuracy — the signals are all weak and buried in noise," Brown explains. And yet, he adds, we're lucky that the event happened just after local midnight, when winds are calmest. "Had this occurred in
the middle of the day I doubt we would see any signals at all," he says.

Brown's rough guess is that the impact energy was equivalent to the explosive power of 500 to 1,000 tons of TNT — which, though powerful in human terms, implies the object was no bigger than a small car. "It was no Chelyabinsk," he says.

So 2014 AA was too small to reach the ground intact. But it must have created one heck of a fireball! The skies over the Atlantic were relatively clear last night. Alas, a search of ship- and plane-tracking websites turned up no vessels in that area — it seems that no one was positioned to witness 2014 AA's demise.

Probably better to read the whole article.



Again, back to Red Mars.

Thanks for looking up with me. 
- LRK -