On October 19, 2017, astronomers first saw an object from another solar system traveling through our own. Zipping into our solar system from above, the interloper, now known as 1I/2017 U1 (‘Oumuamua), swung around the Sun and shot away again, never to return once it leaves our neck of the woods for interstellar space once more.
What have we learned about this mysterious visitor?
‘Oumuamua’s Path
Astronomers were able to record data on ‘Oumuamua (which means “scout” or “messenger” in Hawaiian) for only a brief period of time, although it’s been in our solar system for over a century. “It came into the solar system, inside 1,000 AU, around 1837 or so,” says Karen Meech of the Institute for Astronomy at the University of Hawaii. (1 AU, or astronomical unit, is equivalent to the average Earth-Sun distance of 93 million miles [150 million kilometers]). But ‘Oumuamua wasn’t spotted until last year because it was too far from the Sun to reflect enough light for astronomers to pick it up, even with today’s best telescopes. And once it got close enough to the Sun, it was moving fast, remaining for very little time in the relatively small region where it is visible to modern-day telescopes.
