A solitary frozen traveler has been journeying for millions of years toward the heart of our planetary system. The wayward vagabond, a city-sized snowball of ice and dust called a comet, was gravitationally kicked out of the Oort Cloud, its frigid home at the outskirts of the solar system. This region is a vast comet storehouse, composed of icy leftover building blocks from the construction of the planets 4.6 billion years ago.
The comet is so small, faint, and far away that it eluded detection. Finally, in May 2017, astronomers using the Panoramic Survey Telescope and Rapid Response System... Read more