Closest Asteroid | Universe Today

Written by Jerry Coffey

There is a little debate as to which asteroid is the closest asteroid to Earth. Asteroid FU162 has been determined to be the closest, but because it is less than 10 m in diameter, some scientists do not think that it is as significant as Apophis. Apophis is thought to be much more significant because if its size (at 50 km it would be like a city hitting the Earth at 50,000 kph). FU162 passed the Earth at 6500 km above the surface. The previous close-distance record was held by asteroid 2004 FH, which came within 50,000 km.

The closest asteroid FU162 was discovered on March 31 2004, just hours before its closest approach, by the LINEAR survey system in New Mexico, which tracked it over a 44-minute period. The fast-moving image was later identified in processing the images, but it was too late to obtain further observations since the asteroid exited from the dayside of the Earth.

Tim Spahr of the Minor Planet Center contacted the NASA NEO Program Office at JPL to try to extract an orbit, even though the data spanned only a short arc. No pre-recovery data were found, and indeed this asteroid is so small that it could not be seen by survey telescopes except when it was very close to Earth. Orbit calculations, however, did show that this asteroid had come closer than any previously discovered NEA. Based on this orbit, the asteroid was given an official designation. This asteroid shows the capability of LINEAR to find a few of the tiny NEAs that pass very close by the Earth.

The closest asteroid, FU162, is another indicator that the LINEAR program is running very well and efficiently finding NEAs before they can impact the Earth. Thankfully we have several different programs to make sure that we have early enough warning in case of an impact event.

There is a good article on the NASA website about the closest asteroid. Universe Today has an article on asteroid near misses and Astronomy Cast has a good episode on sky surveys.

Filed under: Astronomy

Tags: Apophis, asteroid FU162, closest asteroid