Known as the $5 Billion Asteroid because it is believed to contain nickel, iron, and cobalt, Nereus made its closest approach to Earth around a month ago on December 11, 2021. During that time, NASA captured some very interesting and detailed images of the asteroid.
Named 4660 Nereus after a sea god from Greek mythology, the asteroid was discovered back in 1982 by Eleanor "Glo" Helin. It is referred to as a Near Earth Asteroid and a Potentially Hazardous Asteroid. It measures 0.33 kilometers in diameter (330 meters or 1,083 feet) and orbits the sun every 661 days. During different times of its orbit, it can be located as close as 0.95 AU to the sun or as far away as 2.02 AU (one AU is the distance that Earth is to the sun).
Nereus belongs to a family of E-type asteroids which are quite bright as they can reflect up to 50% of the sunlight that reaches its surface. To understand this better, S-type asteroids reflect approximately 15% of sunlight, while C-type asteroids only reflect a few percent of the light. It is believed that E-type asteroids could possibly be the source of the exceptionally rare Aubrite meteorites.
When it passed by Earth last month, Nereus was at a distance of just 3,934,298 kilometers from our planet (a little more than 2.4 million miles). The next close approach will occur on March 2, 2031 when Nereus will be at a distance of 17,212,772 kilometers from us (almost 10.7 million miles). Of the next thirteen predicted closest approaches, the nearest it will be to our planet will occur on February 14, 2060 when it will travel within just 1,198,023 kilometers from us (just over 744,000 miles). To put this into better perspective, the moon is located about 384,400 kilometers from us (almost 239,000 miles), so Nereus will be approximately three times further than the moon is to Earth. This means that those wishing to catch a glimpse of the asteroid should be able to do so with a small telescope or powerful binoculars.
On December 10th – just one day before its closest approach to our planet – NASA’s radar observations captured several phenomenal images of Nereus. Scientists from NASA’s Jet Propulsion Laboratory were able to get the most detailed radar images ever of the asteroid thanks to the 70-meter radio antenna at the Deep Space Network’s Goldstone Deep Space Communications Complex close to Barstow, California.
The images were so incredibly detailed that they showed features on its surface, like possible boulders and craters, as well as ridges. This most recent observation of Nereus will provide scientists with even more valuable information regarding its rotation, shape, and its orbital travels.
The images of Nereus can be viewed here.