Observatories around the world send their findings to the NASA-funded Minor Planet Center, which keeps a database of all known asteroids and comets in our solar system.

NASA also has a space probe tracking asteroids to learn more about them. The Dawn probe was launched in 2007 and has already sent back dramatic pictures from the giant asteroid Vesta.

The spacecraft is now heading to the dwarf planet Ceres. Vesta and Ceres are the two most massive objects in the main asteroid belt.

Although scientists know a lot about the path of 2012 DA14, there are many undiscovered near-Earth objects still out there. It's possible that a flash of light and shaking of the ground would be the first indications that something happened. With the Russian meteor, for example, there was no warning.

Many teams of astronomers are using electronic cameras to find these near-Earth objects, but according to NASA, the entire effort consists of fewer than 100 people.

New asteroid adventure in 2016

A mission that's scheduled to launch in 2016 will teach scientists even more about asteroids.

OSIRIS-REx will visit an asteroid called 1999 RQ36, take a sample of at least 2.1 ounces and bring it back to Earth.

"This is going to be the largest sample of an extraterrestrial object returned to Earth since end of the Apollo missions over 40 years ago," said Edward Beshore, deputy principal investigator for the mission, who is based at the University of Arizona, Tucson.

The probe will arrive at the asteroid in 2018, study it, and then bring back the sample in 2023.

1999 RQ36 is made of materials "almost identical to those that were present when the solar system was formed about 4.5 billion years ago," Beshore said. That means studying this asteroid could yield greater understanding about the sources of organic molecules and water that gave rise to life.

Because the asteroid is among those cataloged as a near-Earth object, the mission would further clarify the threat that this particular object poses, and better predict the orbits of other near-Earth asteroids, Beshore said.

Scientists at the University of Arizona are collaborating with NASA and Lockheed Martin Space Systems on this mission.

To better predict the orbits of hazardous objects, the group is looking at the Yarkovsky effect, a force created when the asteroid absorbs sunlight and re-radiates it as heat.

The effect is, at first glance, quite small -- Beshore cited his colleague Steven Chesley's comparison of this effect to the force a person feels when holding grapes in a hand. But over time, it's an important consideration when trying to understand where an asteroid is headed.

"That force, applied over millions of years, can literally move mountains of rock around," Beshore said.

But -- and we can't say this enough: Don't panic over it.