A closer look at the first 'alien' asteroid to pay us a visit

What could be the first interstellar object ever seen dropped by and then sped back to deep space. Scientists rushed to study it as it passed.

It's really rare that we get any visitors from outside the solar system. In fact, astronomers believe they only spotted one for the first time earlier this month when an object that's probably an asteroid whipped by us.

The previously unknown space rock, currently designated A/2017 U1, dropped into our solar system from above the flattish ecliptic plane where most planets, asteroids and comets native to our system rotate around the sun. It then slingshotted around our star and back out to deep space, but not before scientists got a better look at the visitor.

By looking at the asteroid's trajectory, scientists have determined that A/2017 U1 likely came from the direction of the star Vega and the constellation Lyra. It began a close approach to the sun in September, then swung around the star and passed within 15 million miles of Earth on Oct. 14. Problem is, it wasn't spotted until Oct. 18, when it was already heading away from us.

Still, telescopes and astronomers swung into action to observe the retreating visitor. The Liverpool Telescope in the Canary Islands managed to capture this cool sequence last week of the vagabond minor planet:

The alien asteroid is interesting not just because of its potentially interstellar origin, but also because of its speed -- it was seen rocketing by us at 15.8 miles (25.5 kilometers) per second. It also turns out to be a little more colorful than the drab gray rocks we tend to picture when we think of asteroids. In fact, NASA astronomer Joseph Masiero says A/2017 U1 is actually red.

The data that scientists were able to grab isn't great and the margin for error is significant, but Masiero wrote up his findings in a brief paper (PDF) showing that the asteroid looks to be largely featureless and red like many objects from the Kuiper Belt beyond Neptune.