How Are Large Asteroids Tracked?

Since 2005, when the U.S. Congress mandated that NASA identify and track all near-Earth objects that are larger than 140 meters (approximately the diameter of a football field), professional and amateur astronomers have kept a tally of all potential earth-crossers.

Meteorite specialist Denton Ebel, curator in the Division of Physical Sciences, explains how Near-Earth Objects are tracked using a telescope, camera and software.