'Hyperactive' Comet K2 Carries Clues to Birth of Solar System

A "hyperactive" comet that is due to make its closest approach to Earth in less than two weeks' time will give scientists a window into the early days of our solar system billions of years ago.

The comet, known as C/2017 K2, is thought to have been traveling towards our sun for millions of years from a distant region of our solar system known as the Oort cloud—a vast shell of icy rocks orbiting the sun. The Oort cloud is so far away that it would take up to a month to reach it from Earth even at the speed of light.

Scientists have observed K2 since it was discovered in 2017 somewhere between the orbits of Saturn and Uranus. At the time observers noted that the comet was the farthest active inbound comet ever seen and had developed an 80,000-mile-wide cloud of dust around it despite being 1.5 billion miles away from the sun.

Comet in space
A stock illustration depicts a bright comet moving through space with its tail behind it. As comets get near the sun, they become active and release gas and dust. Trifonov_Evgeniy/Getty

Comets are described as active when they start expelling gas and dust as a result of being heated by the sun, which is what gives them their characteristic tails. This activity usually only occurs once comets are inside the orbit of Jupiter, but C/2017 K2 is different.

Nathan Kaib is assistant professor of physics and astronomy at the University of Oklahoma who focuses on the formation of planetary systems. He told Newsweek: "More and more examples of 'hyperactive' comets are being discovered as our observational resources and techniques improve, and 2017 K2 is one of the most extreme examples of this class of comet.

"We are still uncertain what drives the activity of comets at these distances, but the upcoming close passage of 2017 K2 will give us a chance to study one of these objects up close and potentially reveal the mechanisms behind distant cometary activity."

While K2's upcoming pass may be described as "close," it should be noted that the comet will not really come particularly near Earth. In fact, it won't even reach as far as the orbit of Mars, so anyone hoping to see it in person will need to have access to a small telescope. Finder maps that will help with locating it can be found on EarthSky.org. Alternatively, a livestream will be available on the Virtual Telescope Project's website at 6:15 p.m. ET on July 14.

There are some theories as to why K2 and other "hyperactive" comets are able to become active so far away from the sun. One reason could be that K2 is rich in certain types of ice that are more volatile than frozen water—frozen carbon monoxide, for example.

Another interesting characteristic of K2 is that due to its origins in the Oort cloud, it is an example of an object that has probably been unchanged for billions of years. In contrast, most of the best-studied comets so far have tended to come from the Kuiper Belt, which is a much closer region of the solar system that starts around the orbit of Neptune.

David Jewitt, professor of astronomy at UCLA's Earth, Planetary, and Space Science Department in California has studied the comet with Hubble since it was discovered. He told Newsweek: "Oort cloud comets have been out there, tens of thousands of astronomical units from the sun at about 10 degrees above absolute zero for almost the entire 4.5 billion years since the solar system formed.

"K2 has recently been kicked in, but it probably preserves all sorts of ices that are unstable at higher temperatures. That means we can study a chunk of icy matter that has barely changed since the formation epoch—it's a little bit of stuff from the beginning of Solar System time and it has been frozen solid in the deep freeze of the Oort cloud."

Comets in general are often thought of as relics of the early solar system from around 4.6 billion years ago and are even hypothesized as having brought water and organic compounds to Earth, sparking life as we know it.