An international effort to find and catalogue the multitude of so-called near-Earth asteroids has reached a milestone: 15,000 discovered — with many more to go.
This is an artist’s impression of an asteroid. Image credit: Mark A. Garlick, Space-art.co.uk / University of Warwick / University of Cambridge.
A near-Earth asteroid (NEA) is defined as one whose orbit periodically brings it within approximately 1.3 times Earth’s average distance to the Sun — that is within 121 million miles (195 million km) of the Sun. This distance also then brings NEAs within roughly 30 million miles (50 million km) of Earth’s orbit.
It is estimated by astronomers that only about 27% of the NEAs that are 460 feet (140 m) and larger have been found to date.
“The rate of discovery has been high in the past few years, and teams worldwide have been discovering on average 30 new ones per week,” said Dr. Ettore Perozzi, manager of the NEO (near-Earth object) Coordination Centre at ESA’s Centre, Italy.
“A few decades back, 30 were found in a typical year, so international efforts are starting to pay off. We believe that 90% of objects larger than 3,280 feet (1,000 m) have been discovered, but — even with the recent milestone — we’ve only found just 10% of the 330 foot (100 m) NEOs and less than 1% of the 130 foot (40 m) ones.”
“The rising rate of discovery is due to dedicated NEO surveys and upgraded telescopes coming online in recent years. But while we’re making great progress, we still have a long way to go,” added Dr. Kelly Fast, NASA’s NEO Observations Program manager.
The 15,000th near-Earth asteroid discovered is designated 2016 TB57. Image credit: NASA / JPL-Caltech.
The 15,000th NEA is designated 2016 TB57. It was discovered on Oct. 13, 2016 by astronomers at the Mount Lemmon Survey, an element of the NASA-funded Catalina Sky Survey.
2016 TB57 is a rather small asteroid — about 50 to 115 feet (16 – 36 m) in size — that will come closest to Earth today (Oct. 31) at just beyond 5 times the distance of the Moon. It will safely pass Earth.
The discovery of 2016 TB57 was announced in the Minor Planet Electronic Circular (MPEC) newsletter on Oct. 16.
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P. Bacci et al. 2016 TB57. Minor Planet Electronic Circular 2016, no. U03; ISSN 1523-6714
