The Pan-STARRS1 telescope at the University of Hawaii, which is supported by NASA's Near-Earth Object Observations (NEOO) Program, found and tracked 1I/2017 U1 'Oumuamua on October 19, 2017, the first known interstellar object to reach our solar system.
Although it was initially thought to be a comet, observations after it sped by the Sun on September 9, 2017, at a dizzying speed of 196,000 mph, showed no signs of cometary activity (87.3 kilometres per second). Before more recent observations revealed it was somewhat speeding, indicating it behaves more like a comet, it was initially categorised as an asteroid.
This intergalactic intruder, which has visited our solar system for the first time with certainty, has the appearance of a stony, cigar-shaped object with a slightly reddish hue. The object, which its discoverers named "Oumuamua," is up to 400 metres (one-quarter of a mile) long and extremely elongated—possibly ten times longer than it is wide. This aspect ratio is bigger than any asteroid or comet that has been discovered so far in our solar system. Its unusual, elongated shape may offer fresh insights into how other solar systems developed, despite being highly startling and unlike anything found in our solar system.
According to the data, before its unexpected contact, this unique object had been roving the Milky Way for hundreds of millions of years without being connected to any star systems.
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