"Today is a day of an amazing cosmic coincidence," said Dante Lauretta, a NASA scientist and the principal investigator of the agency's new OSIRIS REx mission. The coincidence has to do with an asteroid and a meteor, both catching our attention here on Earth on the same day.
The close call happened earlier this afternoon. An asteroid called 2012 DA14 whizzed past Earth at about 17,000 miles per hour. NASA scientists believe DA14 used to be a part of the asteroid belt between Mars and Jupiter, and is a remnant of our ancient solar system's roots. The asteroid was so close to Earth that it passed underneath the orbit of some of our weather satellites. Even so, we still had plenty of breathing room. It was 17,000 miles from its closest point over the Indian Ocean, and also a comfortable distance of at least 2,000 miles from the nearest satellite orbit.
The approach of DA14 may have been news to us, but NASA has known about it for around 1 year. The meteor that slammed into Russia, however, came as a complete surprise this morning. NASA took a calculated risk when they began studying these near-Earth encounters. Lauretta says, "We started by focusing on the largest asteroids that would cause catastrophic global damage, and we've pretty much ruled out an impact of that magnitude in the foreseeable future." The meteor that hit Russia today was much less than 500 feet in diameter, which is why it flew under their radar.