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HONOLULU (KHON2) – When Oumuamua was spotted last October by the Pan-STARRS1 telescope in Haleakala, scientists were not sure what it was.
In the absence of emission of gas or dusty environment, typical features of comets, Oumuamua has been classified as the first interstellar asteroid.
"An asteroid is basically a rocky remnant of the process of building planets that probably does not have a lot of volatile materials or ice, while a comet has a lot of ice and develops those beautiful tails and clouds gas and dust as they get closer to the sun, "said Karen Meech, astronomer at the Institute of Astronomy at the University of Hawaii." We have called this an asteroid, because when we observed it, there was no tail, no gas or no dust. "
After the initial discovery, astronomers continued to make high-precision measurements of the cigar-shaped rock object using ground-based facilities like the Canada France Hawaii Telescope on Maunakea, as well as the Hubble Space Telescope. The final images were taken with Hubble in January before the object became too weak to observe it as it moved away into its outgoing orbit.
Months of analysis led scientists to change their minds. An article published on Wednesday announced their new assessment: Oumuamua is not an asteroid, but a comet, though unusual.
"The big discovery that surprised us a lot was that it accelerated its orbit, so instead of being controlled just by the gravity of the sun, it received an extra boost," explained Meech. "We looked at a lot, a lot of different assumptions, and the only thing that came up was that it had to be a comet that ejected gas closer to the sun, and away from the sun for that she is actually accelerating.
"Oumuamua is small – no more than half a mile long – and he could have released a small amount of relatively large dust for it to have escaped detection," she added. "What is exciting about the latest result is that even though we have not seen any gas or dust, we can deduce that the chemical composition may be different from the comets in our solar system, so that's not the case. is exciting for me in other star systems may be different. "
Scientists say, unfortunately, that the data they have collected does not provide all the information needed to really answer all their questions.
"He is coming out of the solar system, and further than the planet Jupiter, he is moving away to never be seen again," Meech said. "To really understand Oumuamua, we would need to send a space probe, which is really possible, but it would be very expensive and it would take time to get there, so it's not practical this time- Be ready for the next one. "
Oumuamua means "scout of the distant past" in Hawaiian. Experts say that one in ten of these interstellar visitors pass each year, but they move so fast that scientists have never been able to study one so far.
"It's the first thing we've ever seen of this kind: astronomers have been predicting this for decades, so it was very exciting to see the first arrive," Meech said. "I think the Pan-STARRS in particular will start to see a lot more with the second telescope that starts its investigation, so it's an exciting time to become an astronomer."
Click here for more information on Oumuamua.
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