On October 16, 2019, NASA released footage of Comet 2I/Borisov, a likely interstellar visitor, captured by the Hubble Telescope several days prior. Borisov is the second (basically) confirmed interstellar visitor after ‘Oumuamua. Unlike the rocky asteroid-like composition of its interstellar predecessor, astronomers describe Borisov as active, curiously resembling a standard comet, though its speed and trajectory indicates that it originated from outside of our Solar System.
Since its discovery in late August at a homemade astronomical observatory, researchers continue studying Borisov, noting its chemical composition and structure while offering a historic examination at what planetary building blocks from a distant alien star system might look like. It’s not a simple task to traverse interstellar space, so wherever the comet originated from, its departure certainly occurred a long, long time ago (though not necessarily in a galaxy far, far away).
Hubble caught the image of Borisov at a distance of 260 million miles away from Planet Earth. Its hyperbolic trajectory brings it closest to the Sun on December 7, 2019, racing through our planetary neighborhood at 110,000 miles per hour (watch out Trick-or-Treaters), unaffected by the gravitational forces that bind our Solar System. Sometime in 2020 it will pass Jupiter and resume its infinite voyage back into interstellar space, perhaps visiting other solar systems (or returning to the mother-ship, take your pick).
Most if not all comets found in our Solar System originate from the Kuiper Belt or Oort Cloud, the far fringes of our Solar System, making Borisov quite the hottest ticket in town, darling. Unlike ‘Oumuamua which was discovered on its way out of the Solar System, Borisov’s discovery occurred during its arrival, allowing for a truly remarkable opportunity for scientists to analyze it.
The first two confirmed interstellar visitors serve as a significant marker at the dawn of the Golden Age of Space Exploration. It is believed that our Solar System might host an abundance of interstellar objects, though most may be too faint to see due to our current technological limitations. All scopes are set on Borisov as it continues its adventure within our solar system, many future observations to come. And once again, Hubble with its superior sensitivity and resolution leads the charge to track this interstellar visitor.
Comet 2I/Borisov’s trajectory through our Solar System. Credit: NASA Goddard Scientific Visualization Studio