On the same day that the world's scientists were polishing their telescopes in anticipation of asteroid 2012 DA124, a meteor broke apart over the Ural Mountains in Russia and rained down fire and debris -- reportedly injuring nearly 1,000 people. So why didn't they see this one coming?
Apparently, size matters, explained Andrew Cheng of the Johns Hopkins Applied Physics Laboratory.
"It doesn't take a very large object. A 10-meter size object already packs the same energy as a nuclear bomb," Cheng, who led a 2000-2001 mission for NASA to orbit and land on an asteroid, told FoxNews.com.
The Russian meteor -- estimated to be just 10 tons and about 15 meters or 49 feet wide -- entered the Earth's atmosphere at a hypersonic speed of at least 33,000 mph and shattered about 18-32 miles above the ground. It released the energy of several kilotons above the Chelyabinsk region.
That's relatively small compared with asteroid 2012 DA14, which will make the closest recorded pass of an asteroid to the Earth -- about 17,150 miles -- later today. And while NASA's Near Earth Object Program and other skywatchers track thousands of larger asteroids like it, the countless smaller ones in the heavens are virtually impossible to locate.
€This thing is probably pretty small compared to DA14,€ explained K.T. Ramesh, professor of science and engineering at Johns Hopkins Whiting School of Engineering and founding director of Hopkins Extreme Materials Institute.
€If you think about objects the size of the one that came into Russia, you're probably looking at 100 million up there. Of those likely to intersect Earth, there's less, maybe 100,000,€ Ramesh told FoxNews.com. €Space is pretty big.€
Meteors are pieces of space rock, usually from larger comets or asteroids, which enter the Earth's atmosphere. Many burn up by the heat of the atmosphere; those that strike are called meteorites. And the damage caused by even a small meteorite impact is significant, as seen by the events in Russia.
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.
While scientists scan the heavens frequently and keep track of millions of objects, Cheng said, they don't keep watch continually.
"Extending the searches to objects as small as this thing was will require some serious investment. Is it possible? Yes," he told FoxNews.com. And doing so is clearly important. The impact of a larger asteroid, such as 2012 DA14, would be far worse.
€DA14 -- if that were made of iron, it would get to the ground and cause a significant crater, likely take out a city,€ Ramsesh told FoxNews.com. €Major impact events have the potential to create global catastrophes,€ he said.
Ramesh says that it is hard to predict exactly what would happen to life as we know it if an asteroid were to suddenly slam into the surface of the Earth; the destruction would depend on both the asteroid itself as well as where it hits -- sea, land or urban environment.
To prevent such an event, his team at the Hopkins Extreme Materials Institute has developed a computer model for the impact and disruption of asteroids to help protect against a planetary impact. And to start, we need to put more effort into tracking, especially smaller meteorites such as the Russian one.
€We're getting reasonably good at the big objects. It's the small ones we need to work on,€ he told FoxNews.com.
And we need to know what they're made of. Because the massive 2012 DA14 is made of stone, it would likely break up in the atmosphere rather than make it to Earth. Ramesh stressed the need for education as well. There's a real risk that someone doesn't recognize this as a natural event and sees it as an attack from another country, he warned.
€My great fear is that you have two countries on the brink of war and something like this happens €¦ and someone reacts to it,€ he said.

Russian Meteorite as Old as Solar System - Scientist
The meteorite that exploded above a Russian city in February was about 4.56 billion years old - as old as the Solar System itself, a Russian scientist said Friday.
Mikhail Marov of the Vernadsky Institute of Geochemistry and Analytical Chemistry said scientists had determined the meteorite's age by observing the amount of radioactive isotopes and their decay byproducts, a technique called radiometric dating.
€The age of the Chelyabinsk meteorite - 4.56 billion years - almost coincides with the age of our solar system. This means that we have encountered the so-called €matter of creation,'€ he said. €They [meteorites] hold the history of the processes that took place in the earliest period of the solar system's history.€
Researchers at the Vernadsky Institute said earlier that the meteorite used to be a part of a bigger celestial body.
The meteorite, which exploded above the Ural Mountain city of Chelyabinsk on February 15, is estimated to have weighed about 10,000 metric tons and measured about 17 meters (about 56 feet) in diameter. The blast left about 1,500 people injured, mostly due to glass shattered by the shockwave.

Biggest Chunk of Chelyabinsk Meteorite Goes on Sale
The biggest commercially available piece of the celestial body that blew up over the Russian city of Chelyabinsk in mid-February went on sale this week for a modest but firm price of 2.1 million rubles ($65,000).
The charred heavenly stone, offered at the classified ads site Avito.ru with the slogan €a serious meteorite for serious people,€ weighs 3.36 kilograms (7.4 pounds). It was certified by the Chelyabinsk State University to be, indeed, a meteorite shard and not just a lump of earthly dirt.

The owner, Alexei Usenkov, embarked on a search expedition in the meteorite's wake, personally discovering this and dozens of other, smaller meteorite chunks, which he distributed to friends and relations, local news website 1obl.ru said.
Usenkov wanted to keep his biggest find or hand it over to a museum, but caved in after learning that the ongoing operation to fish out other chunks of the Chelyabinsk meteorite from the local Lake Chebarkul in the Urals is about to yield space rocks bigger than his.
€I think it may serve as a symbol for some Chelyabinsk mall,€ Usenkov told RIA Novosti, speaking about his offer.
The space rock was still on sale as of this article's publication. Usenkov said he hoped to find a buyer before the first anniversary of the meteorite's passing on February 15 and buy a new apartment with the money.
The meteorite weighed 10,000 tons prior to the explosion, according to expert estimates. About 1,500 people were injured in the blast, most of them by glass shattered by the shockwave.
A sect has spawned in Chelyabinsk worshipping the meteorite, which, members claim, bears certain messages for mankind that would usher in a new age on Earth. It remained immediately unclear whether the sect - which has previously staged peaceful protests against the search operation in Lake Chebarkul - was interested in Usenkov's piece of the meteorite.

SKY FALL: WHEN DO METEORITES STRIKE?
A meteor exploded in the sky above Russia on Friday, causing a shockwave that blew out windows and injured hundreds.

Meteor vs. meteorite: What's the difference?
Meteors are pieces of space rock, usually from larger comets or asteroids, which enter the Earth's atmosphere. Many burn up by the heat of the atmosphere; those that strike are called meteorites.

How fast do meteorites go?
They often hit the ground at tremendous speed -- up to 18,642 mph. That releases a huge amount of force.

How common are they?
Smaller strikes happen five to 10 times a year. Large impacts are rarer but still occur about every five years. Most of these strikes happen in uninhabited areas where they don't cause injuries to humans.