The Oumuamua asteroid, a bizarre interstellar planetule shaped like a cigar, flew past Earth last month and is believed to be the first known asteroid from another solar system.
Scientists believe Oumuamua, Hawaiian for "a messenger from afar arriving first," has been flying through space for millions of years and is left over from an alien planet's formation, National Geographic reported.
According to the European Southern Observatory, Oumuamua appears to be a dark, reddish, highly-elongated rocky or high-metal-content object.
The asteroid is several hundred feet long and its speed of 98,000 miles per hours was fast enough to keep it from being captured in the sun's gravitational pull, thus was never being part of this solar system.
The asteroid passed closest to the sun in September 2017 and was reclassified as an interstellar asteroid from a comet, the European Space Observatory said.
Karen Meech, of the Institute for Astronomy in Hawaii, said she found that Oumuamua varies dramatically in brightness by a factor of ten as it spins on its axis every 7.3 hours.
"This unusually large variation in brightness means that the object is highly elongated: about 10 times as long as it is wide, with a complex, convoluted shape. We also found that it has a dark red color, similar to objects in the outer solar system, and confirmed that it is completely inert, without the faintest hint of dust around it."
Astronomers, though, only had a two-week window to examine Oumuamua before it moved on past our solar system, scientists said, per The Atlantic.
"Because the object is moving fast, and the light we get from it is reflected sunlight, the faster it moves away from both the sun and the Earth, the faster it fades in brightness," Meech said.
Olivier Hainaut, an astronomer with the European Southern Observatory, said Oumuamua may only be the solar system's first interstellar visitor.
"We are continuing to observe this unique object," Hainaut said in the ESO statement. "…We hope to more accurately pin down where it came from and where it is going next on its tour of the galaxy. And now that we have found the first interstellar rock, we are getting ready for the next ones."