On Friday an asteroid 150 feet in diameter will pass by Earth. It will be a relatively close call -- the pass will be a record-close approach for a known object of this size.
Though it won't be visible with the naked eye, as it's fairly small, asteroid 2012 DA14 should be visible to viewers in Eastern Europe, Asia, and Austraila using a telescope or a pair of binoculars. It will pass inside the ring of Earth's geosynchronous weather and communications satellites, coming within just 17,200 miles of the Earth's surface at around 12:30 p.m. PT.
Twenty years ago, NASA would not even have been able to detect this threat to Earth, but 15 years ago NASA established the Near Earth Object Program, known by many by its nickname "Spaceguard." With the original goal of finding 1km or larger objects which might be threats, the program has been quite a success, having found 95 percent of those 1km or larger size asteroids, NASA says, but they have also notably found many smaller asteroids, such as the approaching 2012 DA14.
You can following the Near Earth Object Program on Twitter at @asteroidwatch for up to date information on potentially hazardous asteroids and comets that could approach Earth.