For Milner, the object was becoming too intriguing to ignore. So he’s decided to take a closer look.

Breakthrough Listen announced Monday that the program will start checking ‘Oumuamua this week for signs of radio signals using the Green Bank Telescope in West Virginia. The interstellar asteroid is now about twice the distance between the Earth and the sun from our planet, moving at a brisk clip of 38.3 kilometers per second. At this close distance, Green Bank can detect the faintest frequencies. It would take the telescope less than a minute to pick up something as faint as the radio waves from a cellphone. If ‘Oumuamua is sending signals, we’ll hear them.

The chance of an alien detection is, as always, small. But it’s not zero. And Milner thinks we should check—just in case—before ‘Oumuamua is gone for good. The object will pass the orbit of Jupiter next year, and by the 2020s will be hurtling beyond Pluto.

“Whether it’s artificial or not, we will definitely know more about this object,” Milner told me, in a video interview last week.

The new observations will likely be welcomed by the many astronomers who have been scratching their heads for weeks over this space rock. ‘Oumuamua seems to smash many of their predictions about fast-moving interstellar objects, and the more scientists delve into the data, the more puzzles they find.

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The glint of ‘Oumuamua was first spotted by the Pan-STARRS survey telescope in Hawaii during its nightly scan of near-Earth objects like comets and asteroids. Its speed and orbit suggested the object was not bound by the sun’s gravity, and was not of this solar system.

At first, astronomers thought ‘Oumuamua must be a comet, based on decades of scientific literature that predicted its arrival. When our solar system was young, the biggest planets wreaked havoc as they swirled into shape and settled into their orbits. Their movements could jostle nearby material so violently that bits of rock and ice would go flying way out into the universe. The easiest objects to eject were those orbiting at the edge of the solar system, where escaping from the sun’s gravity would be easier. In our solar system, there are far more comets than asteroids lurking near the boundary before interstellar space. Astronomers expected these to be the first interstellar objects they saw.

And so astronomers checked ‘Oumuamua for a coma, a tail of evaporated material that trails comets as they pass near the sun and become heated up. They used telescopes that can detect a sugar cube’s worth of material flying off the object every second. But ‘Oumuamua showed no signs of a coma.

This was the first surprise of many.

Unlike the lumpy, potato-shaped asteroids of our solar system, the 400-meter-long ‘Oumuamua is perhaps 10 times as long as it is wide, an extreme aspect ratio that trumps any of the known asteroids. Astronomers don’t know how the universe could have produced an object such as this. Most natural interactions between an object and its surrounding medium favor the creation of rounded objects, Loeb said, like pebbles on a lakeshore made smooth by lapping water.