On December 11, a large asteroid – about 330 metres in diameter – will safely fly past our planet. Named “4660 Nereus”, the near-earth asteroid is a frequent visitor to near-Earth space. The last time it whizzed past us was on March 22, 2011, and the next visit is expected on March 2, 2031.

Despite the sensational news headlines, 4660 Nereus will skim by at a safe distance of over three million kilometers. This is almost ten times the distance between Earth and the Moon.

Why is it called an apollo asteroid?

Near-Earth asteroids (those whose orbits are near that of Earth) are classified as:

*Atiras: NEAs whose orbits are entirely within the orbit of the Earth
*Atens: Earth-crossing NEAs with axes smaller than that of Earth’s
*Apollos: Earth-crossing NEAs with axes larger than Earth’s
*Amors: Earth-approaching NEAs with orbits exterior to Earth’s but interior to Mars’

4660 Nereus will cross our Earth’s orbit but at a safe distance.

Then why is it a Potentially Hazardous Asteroid(PHA)?

Any near-Earth asteroid that comes near Earth at a distance below 0.05 astronomical units or 7.5 million km is termed as a potentially hazardous asteroid

The International Astronomical Union lists over 1,500 potentially hazardous asteroids.

Close approaches

On December 11, five other near-earth objects are said to make close approaches. According to NASA’s Center for Near-Earth Object Studies, NEOs named 2021 WV1, 2021 WJ3, 2021 XD2, 2021 XG, 2021 WV1 will fly by our planet. 2021 XG is an Aten, while the other four are Apollos.

Today’s treats

On December 6, six near-earth objects — 2021 VX7, 2021 WE1, 2021 WM2, 2021 XT1, 2021 WL2, 2021 XE – will make close approaches.

Last month NASA launched the world’s first planetary defense system to deflect an asteroid. Named DART, the mission will target a small moonlet called Dimorphos and collide with it at a speed of about 6.6 kilometres per second or 24,000 kilometres per hour. The collision is expected to take place next year between September 26 and October 1.