A massive comet that is nearing the end of its multimillion-year trip to the sun has reached the inner solar system and will make its closest approach to Earth in July.
The Hubble telescope first detected comet C/2017 K2 in 2017 when it was the most distant active incoming comet ever recorded.
At that time, the frozen space ball was further distant from our star than Saturn, at a distance of 1.5 billion miles. Even at that distance, the comet, believed to be only 12 miles across or smaller, was heating up and had produced a cloud of dust and gas 80,000 miles wide around it.
Scientists believe that C/2017 K2 originated in the Oort Cloud, a vast sphere of frozen objects that circle our sun much beyond even the most distant planets in our solar system.
The comet has traveled a great distance, through the orbits of Neptune, Uranus, Saturn, and Jupiter before entering the asteroid belt that divides the inner and outer solar systems.
According to SpaceWeather.com, it has entered the inner solar system and is now in our neighborhood. On July 14, it will make its closest approach to Earth, though it will still be further away than Mars.
Comets are composed of dust, ice, and gas, and are remnants of the early solar system. Their orbits bring them near to the sun at times, causing them to heat up and glow.
The "close" flyby of C/2017 K2 will provide scientists and amateur astronomers with a fantastic chance to analyze it.
"The beauty of comets such as this Oort Cloud one is that they carry the chemical fingerprints of the cloud out of which our solar system formed," says Professor Brad Gibson, director of the E.A. Milne Centre for Astrophysics at the University of Hull in the U.K.
"It is relatively rare that we can figuratively—and in some cases, literally—pick up this material, examine it and get a unique, clean, insight into what our sun and planets were built from five billion years ago. Further, the role that comets might have played in transporting water to planets such as Earth remains a very hot topic of scientific research."
Due to their incredibly wide orbits, Oort Cloud comets are especially intriguing since we only see each one once every few million years.
"There are a number of these one-off distant interlopers which make their way to the inner solar system, but as they are relatively rare, each one provides a special insight into the conditions which existed billions of years ago when the solar system was first forming," said Gibson.
Each year, several comets penetrate the inner solar system, according to Alan Fitzsimmons of the Astrophysics Research Centre at Queen's University Belfast. Although C/2017 K2 is one of many comets, it is quite bright, making it an ideal object for scientists to observe as it approaches the sun.
Even though it will not reach Mars' orbit, much alone Earth's, it has already enabled scientists to test how comets respond to being scorched by the sun, as it moved in from beyond Uranus' distance.