A massive icy comet emanating from the trans-Plutonian depths of our solar system is on a course to travel closer to earth than any comet of similar size - at least, so far as scientists have been able to tell.
The comet, known as C/2014 UN271 (Bernardinelli-Bernstein), has a frozen nucleus that measures 80 miles across and is 50x bigger than the core of most comets that travel toward the inner area of our solar system.
It's believed to have a mass of about 500 trillion tons, making it 100,000x more massive than the typical comet found toward the inner solar system.
The comet is traveling at about 22,000 miles per hour, moving from the edge of the solar system towards its the center.
Fortunately, the comet isn't expected to get closer than 1 billion miles from the Sun, which is further away even than Saturn. And it's not expected to get even that close until 2031.
American scientists have been aware of the comet since about 2010, at which point it was 3 billion miles from the Sun (about the same distance between Earth and Neptune. Since then, scientists have used telescopes both on Earth and in space to try and understand more about the comet).
Scientists used NASA's Hubble Space Telescope to examine the comet and estimate its huge size. Right now, scientists can only estimate the comet's size, since it's difficult to distinguish the core from the vaporous aura. Scientists used a computer model to try and differentiate the aura from the comet's core.
It's believed that the comet is billions of years old - meaning it formed during the early days of our universe - and also that it came from the Oort Cloud, the icy enclosure of comets, asteroids and material that forms a spherical shield around our solar system. The Oort Cloud is a theoretical concept - scientists don't have visual proof of its existence. But it's believed this comet could help scientists learn more about the Oort Cloud, which is believed to be 5,000x further from the Sun as the Earth is.