Text Size

From its vantage on the 10,000-foot summit of Maui’s Haleakala, the Pan-STARRS project is tasked to find asteroids that might threaten our planet. Its cameras image a full seventh of the sky every night, sifting the firmament for hints of anything that moves or changes. On October 19, the project’s computers detected a fast-moving object on images taken the previous evening. An alert went out, and other telescopes picked up the chase. Within a few days, it was clear that an asteroid-like visitor from interstellar space had infiltrated our solar system, and we were witnessing the first-ever flyby of a body from another stellar system

A paper published November 20 in Nature by Karen Meech (University of Hawaii) and 17 collaborators reviews and adds to the growing collection of observations that have accumulated during the remarkable encounter. The object, now officially named 1I/2017 U1 (and also known by the Hawaiian “‘Oumuamua,” or messenger from the distant past) is unambiguously extrasolar in origin and exhilaratingly bizarre in nature. Coming from the direction of the solar apex (the point in the sky toward which the solar system is moving as it orbits the galaxy), it streaked toward the sun with an initial speed of 26 kilometers per second, accelerating to 88 kilometers per second at the moment of its September 9 close approach well inside of Mercury’s orbit. When finally caught by Pan-STARRS’ cameras, it had already swung past the sun and crossed Earth’s orbit in the outbound direction. The sun’s waning gravitational influence on it is now steering it toward an exit point from our solar system in the direction of the constellation Pegasus.

To read more, click here.
Category: Science