A newly discovered comet may be visible to the naked eye next year.
On July 26, an astronomer using the University of Hawaii’s Pan-STARRS1 telescope on Haleakala detected a hitherto-undiscovered comet moving from the outer solar system toward the sun.
Based on the comet’s trajectory, it may get close enough to the sun in order to be visible to the unaided eye on the Big Island in early May 2022.
“We’re always on the lookout for asteroids and comets (at Pan-STARRS),” said Robert Weryk, astronomer for UH’s Institute for Astronomy, and discoverer of the comet. “We pick up hundreds of comets like these, but what’s notable about this one is that it will pass close to the sun, which will make it get very bright, maybe enough to see without a telescope.”
The comet, which has been designated Comet C/2021 O3 (PANSTARRS), is a “long-period” comet, Weryk said, meaning it follows an extremely long and elliptical orbit around the Sun. It will reach its perihelion — the closest point to the sun — at around April 21, 2022, Weryk said, whereupon it will begin its centuries-long trip back beyond the outer solar system.
IFA astronomer Richard Wainscoat said the orbits of long-period comets are unpredictable and can be affected by the gravitational pull of other planets, meaning their paths fluctuate every orbital cycle. Comet C/2021 O3 (PANSTARRS) could very well never come this close to the sun again, Wainscoat said, and could get knocked off course, collide with another object or get sucked into Jupiter.
“Even if it does come back, it will take hundreds or thousands of years,” Wainscoat said.
Despite its long orbit, Weryk said the comet is not an interstellar object like ‘Oumuamua, which he also discovered using Pan-STARRS in 2017. That object is not orbiting the sun and is currently on a one-way path out of the solar system to parts unknown.
While the comet approaches the sun, however, astronomers at Maunakea observatories will have the opportunity to observe the composition of the comet. Weryk said this comet is fairly small, which might cause it to disintegrate as it approaches the sun — even if it doesn’t, however, the comet will deteriorate somewhat, with radiation from the sun vaporizing materials within the comet, creating the comet’s signature “tail.”
“We want to study them before and after they approach the sun,” Weryk said. “As we do that, we can get information about their components as they sublimate.”
Weryk said Pan-STARRS’ primary mission is to locate near-Earth asteroids that might pose a threat to the planet. While this comet poses no risk of colliding with Earth, Weryk said that identifying approaching comets may become the telescope’s main focus once the majority of nearby asteroids have been found — although he said that future is a long way off.
Wainscoat emphasized that there is no guarantee that the comet will be visible unaided next year. Neighbor island residents may have the best chance to do so, because of the lack of light pollution, but its visibility still depends on many factors.
The best chance to see it may be in the first few days of May next year, when the comet will hang low in the western sky after sunset, but before the moon gets too bright. If it is visible, it will be faint, Wainscoat said, and stargazers may want to use binoculars or telescopes.
On the other hand, if the comet disintegrates before reaching perihelion, it will only be visible as a very faint cloud of dust, Wainscoat said.
Email Michael Brestovansky at mbrestovansky@hawaiitribune-herald.com.