Sky and Telescope magazine is reporting that Peter Brown (University of Western Ontario) has made a preliminary identification of the impact site of 2014 AA, the New Year’s Earth impacting asteroid. Or more exactly, Dr. Brown has found the point where 2014 AA disintegrated in the Earth’s atmosphere.
Brown and his group used data from infrasound arrays to detect the ‘noise’ of the explosion. The location of the fireball was triangulated by measuring the time of arrival of the infrasound signal at a number of infrasound arrays around the world. This technique has been used to pinpoint the location of other large fireball events as well as the detonation of nuclear weapons. As reported by S&T, the preliminary location is at 40° west, 12° north or about 1,900 miles (3,000 km) east of Caracas, Venezuela.
This sequence of discovery images of Asteroid 2014 AA was taken between 0618 and 0646 UT (between 1:18 and 1:46 am EST) January 1, 2014. The slight “streaking” of the asteroid in the image is due to its rapid motion across the background of stars as it approached the Earth. The brightness of the asteroid is between 18.8 and 19.1 Mv in the images. Image credit: Catalina Sky Survey, Lunar & Planetary Laboratory, University of Arizona
Tonight brings the peak of the best meteor shower you have probably never seen. The best showers of the year are almost always August’s Perseids and December’s Geminids. Number 3 and 4 are usually October’s Orionids or tonight’s shower, the Quadrantids.
The reason I say the Quads are probably the best shower you’ve never seen is two-fold. First as a northern shower, they take place in the dead of winter and only a few days after New Year’s. If the exhaustion from the Holiday’s season doesn’t keep most people inside then the cold definitely will. Also unlike most showers which have broad peaks which last a few days, the peak of the Quads is very narrow. Even if you are observing on the peak night, you can miss much of the show if you are off the peak by only 12 hours.
The International Meteor Organization predicts this year’s Quads peak to take place at ~19:30 UT on the 3rd which suggests the best viewing will be in Asia. But… predicting the peak time for this shower is always difficult so pretty much anywhere on Earth may see the best. The only way to know is to get out and look.
For many years, astronomers were uncertain as to which comet caused the Quadrantids. No known comets was visible on a similar orbit even though the narrowness and strength of the meteor stream suggested it was created recently. We now know that the asteroid (196256) 2003 EH1 is the likely parent body of the Quads. Even though today it appears as nothing more than an asteroid it was a comet in the past and a rather bright one when seen in 1490. Earlier this year I observed 2003 EH1 with the Vatican Obs/Univ. of Arizona VATT 1.8-m as seen in the image below.
[I forgot to add that yesterday’s Earth impacting asteroid, 2014 AA, is not related to the Quadrantid meteor shower. The asteroid and the meteors have very different orbits and the fact that they both intersected the Earth on the same day (or two) is not only a coincidence but shows just how crowded space is with debris.]
Last night was another clear night in Tucson. Though 28 meteors were detected, only 2 were possible Quads. Tonight should see a huge increase in Quadrantid meteors.
Obs Date(UT) Time TOT SPO ANT AHY COM DAD DLM JLE QUA
SAL 2014-01-02 12h 33m 28 23 1 0 0 0 2 0 2
SAL - SALSA3 camera in Tucson (Carl Hergenrother)
Time - Total amount of time each camera looked for meteors
TOT - Total number of meteors detected
SPO - Sporadics (meteors not affiliated with any particular meteor shower)
ANT - Antihelions
AHY - Alpha Hydrids
COM - Coma Berenicids
DAD - December Alpha Draconids
DLM - December Leonis Minorids
JLE - January Leonids
QUA - Quadrantids
2014 has started off with fireworks! The first designated asteroid of the year, discovered only half an hour before midnight on New Year’s Eve (Tucson local time) but 6.5 hours into 2014 in Universal (or Greenwich Mean) time by Richard Kowalski of the Mount Lemmon Survey, was an Earth impactor.
Based on 7 astrometric measurements taken over the course of 70 minutes, the Minor Planet Center’s orbit has determined that 2014 AA impacted the Earth around Jan. 2.2 +/- 0.4 UT somewhere along an arc stretching from the eastern Pacific Ocean, southern Nicaragua, Costa Rica, very northern Columbia and Venezuela, a long stretch of the Atlantic Ocean and the African countries of Senegal, Gambia, Mali, Burkina Faso, Niger, Chad and Sudan. Maps of the possible impact points have been produced by Bill Gray and can be found here and here. The most likely impact point is in the Atlantic Ocean off the coast of western Africa.
With an absolute magnitude of ~30.9, 2014 AA was likely a very small asteroid with a diameter on the order of 1-5 meters. Such an object would have posed no danger to the ground though small meteorites may have survived passage through the atmosphere. If it fell in the ocean there is a good chance that no one directly witnessed it though the signature of its resulting fireball may be found in weather satellite images.
This marks the second time that an asteroid was detected in space prior to impact. The first impactor, 2008 TC3, was also found by Rich Kowalski and the Mount Lemmon 1.5-m reflector. That body was observed to fall over northern Sudan and led to the recovery of many meteorites (named Almahata Sitta). More on the fall of 2008 TC3 and Almahata Sitta can be found at this blog (here, here, here, and here), the Meteoritical Bulletin and Wikipedia.
Note, that for every small asteroid discovered before hitting the Earth (of which we’ve seen only two) there are many thousands of similar sized objects (and countless smaller ones) that go undetected until seen as brilliant fireballs or meteors. Hopefully planned upgrades to current asteroid surveys such as the Catalina Sky Survey/Mount Lemmon Survey and future surveys like ATLAS will result in more warning time for incoming asteroids.