Astronomers Just Discovered a Tiny Planet Heading Toward Our Inner Solar System

There's a small world making its way towards Earth.
Brad Bergan
A depiction of a distant dwarf planet Eris and its moon.ESO/L. Calçada and Nick Risinger / Wikimedia

The edge of our solar system is brimming with wondrous objects from the ancient past, but one of them is on its way toward Earth's neighborhood.

Astronomers have identified a minor planet on its way for a close pass with the sun in a segment of its maddeningly-long 600,000-year orbit, according to an initial report from New Atlas.

We're in no danger of impact, but on cosmic scales, it's not a gross exaggeration to call this an intimate encounter. And, in case you missed it, the last time the object came this close, the Neanderthals were still alive.

The tiny planet will come within 11 AU of the sun

Called 2014 UN271, the astronomical object was only recently discovered in data captured between 2014 and 2018 during the Dark Energy Survey. Its size is estimated somewhere between 62 and 230 miles (100 and 370 km) in diameter. If this is a comet from the outer solar system, it's an especially colossal one.

"[That] puts it on a similar scale, if not larger than, Sarabat's huge comet C/1729 P1, and almost undoubtedly the largest Oort Cloud object ever discovered — almost in dwarf planet territory!" said a citizen astronomer named Sam Deen in a post to the Minor Planet Mailing List (MPML) forum. The most notable feature of 2014 UN271 is its trajectory around the sun, which is wildly eccentric, moving in its orbit from the Oort cloud to the inner solar system and back again, from the familiar interior where life as we know it flourished to the very extremities of our solar system, every 612,190 years.

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And we'll get to see it when it makes its closest pass of Earth this time around. As of writing, 2014 UN271 is roughly 22 Astronomical Units (AU) from the sun — one AU equating to the distance from the sun to the Earth. In other words, the mini planet is already closer to the sun than Neptune, at roughly 29.7 AU. And it's coming closer, traversing a vast distance of 7 AU in just seven years. It will reach its closest pass of the sun in 2031, moving to within 10.9 AU of our sun, pushing close to Saturn's orbit.

The tiny planet will swing out to a distance of nearly 60,000 AU

However, the little planet should form the typical coma and tail of a conventional comet before its closest pass, which is a natural process involving the vaporization of icy material due to the sun's immense heat. If all goes according to theory, astronomers will enjoy the priceless opportunity to examine a rare Oort cloud object without having to send an entire probe past Pluto. But sadly, amateur astronomers without a powerful telescope probably won't see anything overwhelmingly exciting. Unlike, say, Halley's comet, Deen calculated that 2014 UN271 will probably only become as bright as Pluto, or even the relatively dimmer comparative planetary body, Pluto's moon: Charon. Despite this heartbreaking setback, we can rest assured that the professionals won't hoard their treasure, and images of the rare encounter will flood the internet as soon as they're available.

Once the tiny planet has made its figurative mark on the world, 2014 UN271 will swing wide and fly back into the horrific darkness on its return journey to the ancient Oort cloud for hundreds of millennia, passing from the Earth's memory, until it reaches a staggering maximum distance from the sun at nearly 60,000 AU. Whatever you're doing this lifetime, your very distant descendants won't have the opportunity provided by this incredibly rare event. Don't miss it.

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