Top Astronomy Stories in 2013

This is the time of year to highlight some of the great discoveries of the last year, and we have plenty to ponder.  CBS news highlights events such as the discovery of the Higgs Boson, life in Antarctic lakes, more evidence of water on Mars, and the Chinese moon landing.  I would add the Indian mission to Mars as another key event.

CNN’s list of 2013 scientific stories included the stray asteroid that hit the Russian city of Chelyabinsk in February 2013 (notice this is a story rather than a discovery, though the people in Russia certainly discovered something new about the risk of life here on the third rock from the sun).

Wired magazine covered both discoveries and stories, with discoveries including estimates that our galaxy may contain about 10 billion Earth-like planets (using data from NASA’s Kepler space telescope).  Top stories included Mars One, the plan to send humans one-way to Mars in 10 years, and the mysterious environment encountered by Voyager 1 at the edge of the Sun’s heliosheath.  Wired also discusses the diminishing availability plutonium-238, which may impact out ability to repeat Voyager-like missions in the future.

Meteorite Damage in Russia

While 2012 DA14 safely passed the earth on Friday, another unexpected rock plummeted to Earth and struck Russia (again) the very same day.  More than 100 years after the Tunguska, Siberia, meteor strike, a new meteor struck Russia in the Chelyabinsk region (see map below).  The two regions are about 3,000 miles apart.

The meteor was estimated to be about 55 feet and weighing approximately 10,000 tons. The incoming explosion released nearly 500 kilotons of energy and early estimates indicate 1,000 people where injured, primarily from broken glass as windows shattered.

According to the Associated Press, 

The explosions broke an estimated 100,000 square meters (more than 1 million square feet) of glass, city officials said.

Chelyabinsk health chief Marina Moskvicheva, said Friday that 985 people in her city had asked for medical assistance. The Interfax news agency quoted her as saying 43 were hospitalized. Athletes at a city sports arena were among those cut up by the flying glass.

NASA stated that such occurrences are to be expected every 30 years or so, and noted that this event and the 2012 DA14 asteroid were unrelated:

"We would expect an event of this magnitude to occur once every 100 years on average," said Paul Chodas of NASA's Near-Earth Object Program Office at the Jet Propulsion Laboratory in Pasadena, Calif. "When you have a fireball of this size we would expect a large number of meteorites to reach the surface and in this case there were probably some large ones."

The trajectory of the Russia meteor was significantly different than the trajectory of the asteroid 2012 DA14, which hours later made its flyby of Earth, making it a completely unrelated object. 
 
It is understandable that people will conflate the two events occurring on the same day.  I would like to know the odds of this event happening.  

In a February 14 editorial in The Wall Street Journal, the authors provided additional estimates on the likelihood of future meteor strikes,

The chance of another Tunguska-size impact somewhere on Earth this century is about 30%. That isn't the likelihood that you will be killed by an asteroid, but rather the odds that you will read a news headline about an asteroid impact of this size somewhere on Earth. Unfortunately, that headline could be about the destruction of a city, as opposed to an unpopulated region of Siberia.

The chance in your lifetime of an even bigger asteroid impact on Earth—with explosive energy of 100 megatons of TNT—is about 1%. Such an impact would deliver many times the explosive energy of all the munitions used in World War II, including the atomic bombs. This risk to humanity is similar to an individual's odds of dying in a car accident.

This was published one day before the meteor struck Russia.  I wonder if the authors would update their estimates today (or turn in their car keys).