On Wednesday afternoon, astronomers will try to see if they can detect any radio signals coming from a strange object that recently hurtled past Earth—and that almost certainly comes from another star system.
If it really does come from outside the Solar System, ʻOumuamua (the name comes from the Hawaiian for “messenger from afar arriving first”) is the first interstellar object we’ve ever seen in our own star system. With a dark red color that suggests hundreds of millions of years’ worth of cosmic irradiation, the cigar-shaped object is moving too fast—up to 196,000 miles per hour—to be caught in the Sun’s gravity.
ʻOumuamua is perhaps a quarter-mile long and far more elongated than asteroids are. It spins on its axis once every 7.3 hours or so. The object was first spotted in mid-October as it passed Earth (at a distance of 85 times that between us and the Moon), and last month NASA said it appeared to be made of “rock and possibly metals.”
So, is ʻOumuamua natural or artificial? The former is of course more likely, but Breakthrough Listen, a project that is trying to find evidence of extraterrestrial life, is on the case.
The project, funded by Russian tech billionaire Yuri Milner, announced Monday that it was focusing its attention on the interstellar interloper. At 3 pm ET on Wednesday, the Green Bank Telescope in West Virginia will track ‘Oumuamua across four radio bands, in search of some kind of signal.
According to Listen, it should be possible for the Green Bank instrument to pick up a signal as weak as that from a cellphone.
“ʻOumuamua’s presence within our solar system affords Breakthrough Listen an opportunity to reach unprecedented sensitivities to possible artificial transmitters and demonstrate our ability to track nearby, fast-moving objects,” said Andrew Siemion, the director of the Berkeley SETI Research Center. “Whether this object turns out to be artificial or natural, it’s a great target for Listen.”
When ʻOumuamua was initially observed by the University of Hawaii’s Pan-STARRS1 telescope, it was first classified as a comet, then an asteroid. It now carries the designation “1I/ʻOumuamua”—the “I” stands for interstellar, and the “1” shows it is the first object ever to be defined as such.