A small asteroid designated 2012 TC4 will pass very close to Earth on Oct. 12, and even though scientists cannot yet predict exactly how close it will approach, they are certain that the asteroid will fly by at a safe distance from our planet. This asteroid has not been seen since the week it was discovered in October 2012, when it sped past Earth at about one-fourth the distance from Earth to the moon. Estimated to be only 30 to 100 feet (10 to 30 meters) in size, the asteroid has been too distant and too faint to be detected over the last five years. As it starts to approach Earth this summer, large telescopes will be used to re-establish its precise trajectory. The new observations are expected to help refine knowledge about its orbit, narrowing the uncertainty about how far it will be from Earth at its closest approach in October.

“We know the orbit of 2012 TC4 well enough to be certain that it won’t hit Earth,” said Paul Chodas, manager of the Center for Near-Earth Object Studies (CNEOS), at NASA’s Jet Propulsion Laboratory, Pasadena, California. During the close approach on Oct. 12, the space rock will pass no closer than 4,200 miles (6,800 kilometers) from our planet, and more likely much farther away, as far as 170,000 miles (270,000 kilometers) or two-thirds of the distance from Earth to the moon. These calculations are based on seven days of tracking 2012 TC4 after it was discovered on Oct. 5, 2012, by the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) from Haleakala on the island of Maui, Hawaii.

From brightness measurements made during the week it was observed in 2012, the size of this asteroid is estimated to be in the range of 30 to 100 feet (10 meters to 30 meters). For comparison, the asteroid that hit Earth’s atmosphere near Chelyabinsk, Russia, in February 2013 was roughly 70 feet (20 meters) across.