Welcome to Quantum Magazine's podcast.

Each episode we bring you stories about developments in science and mathematics.

I'm Susan Vallett.

In 2017, a weirdly shaped rock with a strangely erratic orbit swept through the solar system, leaving as quickly

as it arrived.

Astronomers soon realized that it wasn't from around here.

It was a mystery.

The strange rock punched through Earth's orbital plane from the top down, like a dart thrown at the concentric rings of a dartboard.

It moved super fast, way too quickly to be caught in the Sun's gravity.

It was also extremely dark and seemed oddly elongated.

In a NASA JPL video, Paul Chodas of NASA's Center for Near Earth Object Studies

describes it. We think this object, 2017 U1, is very long, perhaps 400 meters or so, long, and very

narrow, skinny, perhaps maybe 40 meters or so in the other dimensions. That's a very unusual shape.

We don't see that in our solar system. None of the asteroids in our solar system look like that. But because it was so speedy,

many of its properties will forever remain a mystery. The object was the first interstellar asteroid

ever observed, says Chodas in that same NASA JPL video.

This object is simply a piece of another solar system that was expelled, and it has been

traveling through interstellar space for hundreds of millions of years, billions of years.

We don't know.

Researchers named the asteroid Omuamua for the Hawaiian word scout.

The discoverers wanted to embody the idea of a messenger from the distant past reaching out to us.

The appearance of Omuamua represents a giant shift in astronomy.

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