MYSTERY SOLVED: Scientists crack secret of 'interstellar object' Oumuamua
LOS ANGELES, CALIFORNIA: In 2017, the "interstellar object" Oumuamua flew by Earth, and its peculiar features baffled scientists. Comets have water vapor, that is blasted outwards, functioning as a thruster as it approaches the sun. This is why comets begin to speed up. Both a dust tail and a bright halo known as a comet's "coma" are signs of this gas expulsion. But Oumuamua had neither and was still accelerating. Many believed it was an alien spaceship propelled by an extraterrestrial engine, as a result of this.
But now, scientists from Cornell University and the University of California, Berkeley in the US, have proposed a new, easier answer. It's possible that the absence of a trail was caused by the tiny comet exhaling a thin shell of hydrogen gas that was invisible to telescopes, as reported by Time.
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Hydrogen gas that was invisible to telescopes
The first author of the current study, Dr. Jenny Bergner, said, "For a comet several kilometers across, the outgassing would be from a really thin shell relative to the bulk of the object, so both compositionally and in terms of any acceleration, you wouldn't necessarily expect that to be a detectable effect." He further added, "But because Oumuamua was so small, we think that it actually produced sufficient force to power this acceleration," as reported by DailyMail.
'Dirty snowballs'
Astronomers refer to comets, which are balls of ice, dust, and rocks, as "dirty snowballs" because they often originate from the Oort cloud, a ring of icy material at the boundary of our solar system. When gravitational forces pull them away from the Oort cloud, they migrate into the inner solar system, where they become more conspicuous as they get closer to the sun's heat. The comets melt as they get closer, ejecting a torrent of molecules torn from their surface by solar radiation and plasma, including water vapor, dust, and other molecules, as per reports.
This provides them a kick outwards that somewhat changes the shape of their orbit around the sun and manifests as a hazy, outward-facing tail. A coma, a thin, gaseous atmosphere containing more ice and dust, is also present around comets. Oumuamua, which researchers in Hawaii observed passing by Earth on October 19, 2017, had a somewhat different appearance and behavior, as reported by DailyMail.
Oumuamua was shaped like a cigar
First of all, it was traveling at high speed—roughly 97,200 mph (156,428 kph)—which scientists determined could not have been caused by the sun's gravity alone. Oumuamua was shaped like a cigar and was tumbling through space, according to additional analysis, as reported by Scientific American. This is why the alien spaceship theory became popular at first, even in scientific circles.
