Milestone – More than 30 000 near-Earth asteroids of all sizes discovered
Our observatories have now discovered a total of 30 056 near-Earth asteroids in the Solar System, setting a new milestone for humanity.
An asteroid is called a near-Earth asteroid (NEA) when its trajectory brings it within 1.3 Astronomical Units (au) of the Sun. 1 au is the distance between the Sun and Earth, and so NEAs can come within at least 0.3 au (45 million km / 28 million miles), of Earth’s orbit.1
Currently, near-Earth asteroids make up about a third of the roughly one million asteroids discovered so far in the Solar System, with most of them residing in the asteroid belt between Jupiter and Mars.
Asteroids have been cataloged by astronomers for more than two centuries since the very first asteroid, Ceres, was discovered in 1801 by Giuseppe Piazzi. The first near-Earth asteroid, (433) Eros, was discovered nearly one hundred years later, on August 13, 1898.
As of October 14, 2022, our observatories have discovered a total of 30 173 near-Earth objects (NEOs) – including both comets and asteroids.2
Of that number, 30 056 are near-Earth asteroids (NEAs). By their groups, the numbers are as follows:
- 28 Atira
- 2 345 Aten
- 16 835 Apollo
- 10 848 Amor
- 153 PHA-km (Potentially Hazardous Asteroids – PHA)
- 2 291 PHA
- 857 NEA-km
- 10 237 NEA-140m
Currently, none of the near-Earth asteroids discovered so far are a concern, for at least one hundred years.1 Some of the smaller objects will and do impact Earth – but the most common are also the smallest and have little effect, except for creating trails of shooting stars as they burn up in the night sky.
When it comes to large and potentially devastating asteroids larger than 1 km (0.6 miles) across and above, the majority have been discovered and none show an impact risk for at least a century.
The current priority are the medium-sized asteroids a few hundred meters in diameter.
References:
1 30 000 near-Earth asteroids discovered and rising – ESA – October 12, 2022
2 Discovery statistics – CNEOS – Accessed on October 14, 2022
Featured image credit: NASA/EYES
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