COMET? ASTEROID? SPACESHIP? - 'Oumuamua, the first interstellar object that visited the solar system stirred up debates and arguments over its classification. Some scientists consider 'Oumuamua as an asteroid, some believe it is a comet, and there are those who push for the idea that it might be a spaceship.
Since the first time the Hawaiian Pan-STARRS telescope laid visuals on the visiting heavenly body on October 19, 2017, studies have been done supporting its nature as an asteroid. However, recent researches that suggest the possibility of 'Oumuamua being a comet.
'Oumuamua's trajectory suggests that it did not orbit the Sun but instead it came from outside the Solar System, visited briefly, and left. During its brief visit, 818 observations of the interstellar object and some strange things about it were found by scientists. Aside from its elongated shape, its complex rotation is also notable. Another unusual thing about 'Oumuamua is how it increases in speed as it moved along and that speed is more than the expected acceleration if caused by the Sun's gravity.
The interstellar rock has sparked a number of debates and theories. Some hypothesize for 'Oumuamua to be a comet, however, the rock did not have any observable tail. Its surface is not spewing any observable carbon gas as well. Some think that it is an asteroid which formed closer to its star. Some see it as a solar sail because of it being a flat object. There are several speculations raised with 'Oumuamua's visit.
These speculations are later put to bed by Darryl Seligman and Greg Laughlin from Yale and Konstantin Batygin from Caltech in their paper which The Astrophysical Journal will soon publish. In their paper, the three explained how 'Oumuamua's unusual trajectory can be caused by its volatile-rich and gas-venting structure. Simply putting it, 'Oumuamua resembles a comet even of no conventional tail or gas was observed.
The team further explained why there was no tail visible in their simulation of an elongated pill-shaped object that emits a jet of vaporized particles like water vapor. Their simulation model resulted in similar behaviors that were observed in 'Oumuamua.
Still, some are not convinced by the three scientists 'explanations. Avi Loeb from Harvard challenges their explanations because their findings are said to be based on the assumption that extrasolar objects act like Solar System objects. On the other hand, Roman Rafikov from the University of Cambridge points out that their paper is requiring an ideal shape to be considered as a comet.
In general, there are a number of arguments in the study of 'Oumuamua. Scientists are hoping to come across more interstellar objects that could aid in further researches and finally drawing out an answer.
