The National Aeronautics and Space Administration (NASA) has said that an asteroid, which is the size of the Eiffel Tower, is headed towards Earth. The asteroid – 4660 Nereus – is considered a unique piece of rock by scientists.

The asteroid has been classified as a “potentially hazardous” piece of rock because of its near proximity to Earth. NASA, in a statement, said that it expects the asteroid to be at its closest point to Earth over a 20-year period. The event will is expected to occur on December 11.

The 4660 Nereus, a 330-meter asteroid in the shape of an egg, was discovered back in 1982. As per the scientists, it will be within 2.5 million miles of Earth. Despite sounding far away, scientists consider it to be in close proximity by cosmic standards. To put things in perspective, the distance is about ten times farther away than the moon.

As per NASA, an asteroid or a comet is only considered to be a near-Earth object when it comes within approximately 30 million miles of Earth’s orbit.

Nereus has for a long time been a target for a space mission multiple times, Forbes reported. It has been so because of its egg shape, size and orbital path around the sun. Also, it makes for an ideal asteroid to visit. Forbes also mentioned that for a robotic spacecraft to enter orbit around Nereus it would take a year.

In 2009, researchers and scientists considered Nereus “a strong candidate for a rendezvous mission.”

According to Asterank, a database that monitors more than 600,000 asteroids, said that the Nereus is estimated to be at a value of $4.71 billion. Thus making it one of the most cost-effective asteroids to leverage for mineral resources.

It is believed that the asteroid is thought to contain billions worth of nickel, iron and cobalt. Asteroid mining, as a concept, gained popularity in the early 2010s and is expected to fly off again.