The Russian Meteor

The title might, at first glance, suggest to some that the Russian automotive industry has arisen, phoenix like from the ashes of its embarrassingly mediocre past, to produce a vehicle that is taking the word of super cars for the super rich, by storm.  The truth, however, is that what people with a sound knowledge of matters astronomical and of meteors in particular, have been warning about for several decades, has finally happened; the Earth was hit by a fair sized chunk of space rock that appeared out of nowhere while we were all watching the decoy, asteroid 2012 DA14, wiz by harmlessly in the opposite direction.  The current scientific opinion is that this object does not appear to have been related to asteroid 2012 DA14 in any way.

The question of what exactly a meteor is, is a bit confusing.  The International Astronomical Union (IAU) defined a meteoroid in 1961 as “considerably smaller than an asteroid and considerably larger than an atom.”  Then, in 1995, Martin Beech and Duncan Steel proposed a new definition which set the size to between 100 µm and 10 m.  Following the discovery of an asteroid smaller than 10 m, Alan Rubin and Jeffrey Grossman, in 2010, proposed a size limit of between 10 µm and 1 m in diameter to meet the IAU’s original definition.

When a meteoroid enters the Earth’s atmosphere, leaving its bright trail of superheated particles, it becomes a meteor and only when it hits the ground is it a meteorite.  These name tags are not interchangeable, as some of the persons writing articles and posts seem to think.  However, this one was larger than 1 m and Detlef Koschny, Head of Near-Earth Object activity at ESA’s Space Situational Awareness (SSA) programme office, says that, when all the information has been evaluated this will probably be classified as a small asteroid rather than a meteor.

The only other recorded event of this nature was also in Russia; the Tunguska-event of 1908 in Siberia, so perhaps it would be more appropriate to refer to this event as the Chelyabinsk meteor or, eventually, the Chelyabinsk asteroid.  It was detected by a worldwide network of infrasound sensors before it surprised the citizens of Chelyabinsk and the data from these various stations, as processed by Peter Brown at the University of Western Ontario, Canada, currently indicates that the object was about 17 m in diameter and probably had a mass of 10 000 tons (about one third of the mass of asteroid 2012 DA14) when it entered the Earth’s atmosphere at around 18 km/sec (more than 64 000 km/h) over Alaska.

From the point where it entered the atmosphere to the final disintegration at an altitude of about 10 km above Chelyabinsk, 6 500 km away, (at 01:12.00 SAST) took just over 32 seconds.  The Chelyabinsk meteor’s trajectory was very shallow and it was visible for a total of around 30 seconds and is reported to have been brighter than the sun when it passed over observers on the ground.  Had the trajectory not been as shallow it might have made a direct hit anywhere between Alaska and Chelyabinsk, most likely somewhere on the North American continent or in the North Atlantic Ocean.

Information on the Chelyabinsk meteor itself is far from complete and will continue to be updated as data from more and more sources are collected and collated.  Media reports from Chelyabinsk have so far disclosed that upward of 1 100 people were injured in the blast and as many as 4 000 buildings were damaged, but these figures are by no means final.  According to the official webpage of the regional governor a large hole, that suddenly appeared in the ice of Lake Chebarkul, was probably caused by a substantial fragment of the meteor, but divers have been unable to find anything.  Other reports indicate that many of the pieces fell close to the town of Chebarkul and other, as yet unsubstantiated, reports claim that the object was intercepted by the air defence complex at the Urzumka village near Chelyabinsk.

Thomas Reiter, ESA’s Director of Human Spaceflight and Operations said, “Today’s event is a strong reminder of why we need continuous efforts to survey and identify near-Earth objects.”  ESA’s SSA programmes are developing a system of automated optical telescopes that can detect asteroids and other objects in solar orbits. ESA cooperates with international survey efforts to achieve the goal of spotting near-Earth objects larger than 40 m at least three weeks before closest approach to our planet.  ESA’s Optical Ground Station in Tenerife, Spain is a key element in these programs and SSA also participates in other European and international asteroid survey activities. ESA sponsors astronomy groups in Europe that carry out surveys with their own equipment and allocates observation time on the Tenerife telescope too.

Go here to read more about the Chelyabinsk meteor  or go here read more about ESA.

A twist in the tail of this otherwise very serious affair is that a Russian MP has blamed the entire occurrence on a US secret arms test, according to a report in the Journal of Turkish Weekly.  Read more about this bizarre allegation.

Asteroid 2012 DA14

So what is all the hype about?  After all this space rock is going to miss us. Yes, but in terms of astronomical distances this is a close miss that could easily have been a direct hit. At its closest approach to Cape Town it will be a tad over 34 thousand km away, which is less than a tenth of the distance between the Earth and the Moon and will place it inside the orbit of several of the geosynchronous communication satellites that orbit the Earth.

Asteroid 2012 DA14 is just over 40 metres in diameter and has a mass of around 190 000 metric tonnes.  Those of you that are mathematically inclined can use its speed of around
25 000 km/h to calculate the amount of energy it would generate, if it hit the Earth.

Remember also that this particular rock is in an orbit that brings it into the vicinity of the Earth twice a year.  How many attempts is it going to take to eventually score a hit?

For a finder chart visit Auke on psychohistorian and for more details and other charts visit DISCOVER’s Bad Astronomy page or go to MailOnline.  You can also visit the One Minute Astronomer for supplementary information on the asteroid and on the two comets currently visible.