ʻOumuamua

Oumuamua is the first known interstellar object detected passing through the Solar System. Formally designated 1I2017 U1, it was discovered by Robert Weryk using the Pan-STARRS telescope at Haleakalā Observatory, Hawaii, on 19 October 2017. It is a small object estimated to be between 100 and 1,000 metres long, with its width and thickness both estimated to range between 35 and 167 metres. It has a dark red color, similar to objects in the outer Solar System, but showed no signs of having a coma.

About ʻOumuamua in brief

ʻOumuamua is the first known interstellar object detected passing through the Solar System. Formally designated 1I2017 U1, it was discovered by Robert Weryk using the Pan-STARRS telescope at Haleakalā Observatory, Hawaii, on 19 October 2017. It is a small object estimated to be between 100 and 1,000 metres long, with its width and thickness both estimated to range between 35 and 167 metres. It has a dark red color, similar to objects in the outer Solar System, but showed no signs of having a coma. The object has a rotation rate similar to the average spin rate seen in Solar System asteroids, but many valid models permit it to be more elongated than all but a few other natural bodies. Its planetary system of origin, and the age of its excursion, are unknown. It was originally classified as comet C2017 U1, but was later reclassified as asteroid A 2017 U1. The name comes from Hawaiian ʻoumuamua ‘scout’ ), and reflects the way this object is like a scout or messenger sent from the distant past to reach out to humanity. It roughly translates to ‘first distant messenger’ The name Rama was suggested, the name given to an alien spacecraft discovered under similar circumstances in the 1973 science fiction novel Rendezvous with Rama by Arthur C. Clarke. In July 2019, astronomers reported that  OumUamua was an object of a \”purely natural origin\”.

Once it was unambiguously identified as coming from outside the Solar system, a new designation was created: I, for Interstellar object. As the first object so identified, was designated1I, with rules on the eligibility of objects for I-numbers, and names to be assigned to these interstellar objects, yet to be codified, have not yet been codified. By the end of October, ʼOum uamua had already faded to magnitude ~23, and in mid-December it was too faint to be studied by even the largest ground-based telescopes. It could be a remnant of a disintegrated rogue comet, according to a NASA scientist. It would eventually leave the Solarsystem and continue into interstellar space. Extrapolated and without further deceleration, the path of ˚Oum u amua cannot be captured into a solar orbit, so it would eventually left the solar system and continue to interstellar space, as predicted by the International Astronomical Union. It has not been seen in the sky since September 2017, and was not seen in STEREO-1 observations near its perihelion on September 9, 2017, limiting its brightness to 5 mag mag. It was first observed, about 33 million km from Earth, and already heading away from the Sun. Despite its close approach to the Sun, �’Oum  uamaua is small and dark, and is too faint and moving to be compared to other objects.

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