Comet could be a spectacular guest at April 8 esclipse

Feb. 27—WATERTOWN — A comet is on a path that could add star power to the April 8 eclipse.

Astronomy magazine reported in its April 2023 issue that amateur astronomer, astrophotographer and longtime comet-lover Dave Weixelman of Nevada City, California, discovered that comet Pons-Brooks will be near the eclipsed sun during totality of the 2024 total solar eclipse. Watertown is in that path of totality, and the city is expected to attract thousands of people to view the phenomena.

The Astronomy magazine article was headlined, "The 'Devil comet' will be visible during the 2024 total solar eclipse."

Meanwhile, Scientific American reported on Friday that the comet, discovered in 1812, will make its closest approach to the sun in April, with its closest approach April 21. One planetary scientist told Scientific American that the comet is one of the brightest in history.

It's uncertain how visible Comet 12P will be during the eclipse, even in favorable weather. But if clear, stars and some planets will come into view.

"Although the sun will be blocked at that time, the sky won't reach true nighttime hues — it will be more like twilight — and our home star's outer atmosphere, or corona, will be shining as well. Based on the current observations, during totality, the comet may be just barely visible to the naked eye, or sky watchers may need binoculars to spot it," Scientific American said in its report by Meghan Bartels.

Aileen A. O'Donoghue, Henry Priest Professor of Physics at St. Lawrence University in Canton, said she recently learned of the comet's potential to be viewable during the eclipse by reading the Astronomy magazine article.

"The comet is certainly out there and could add to an already spectacular event," O'Donoghue said. "We usually can't see comets that close to the sun because of the glare of its light. I hope it turns out to be spectacular."

But comets, O'Donoghue said, are "famously fickle."

"They glow due to volatile ices (water ice, methane ice, ammonia ice) being sublimated by sunlight and that gas bursting off the comet's surface dragging some dust with it that reflects the sunlight," she explained.

That creates what we see as the coma, or nebulous envelope — the bright region at the head of the comet and the tail.

"The bursting is not predictable so comets often brighten and dim unexpectedly," O'Donoghue said. "Let's hope this one brightens near the sun on April 8."

Wiexelman told Astronomy magazine that during the eclipse, comet Pons-Brooks will be slightly southeast of Jupiter and about 24 1/2 degrees northeast from the eclipsed Sun. "This means the comet will be potentially visible at mid-eclipse to those searching with binoculars or a telescope, or capturing the scene with a camera," the magazine says.

The "famously fickle" nature of comets could also bring something spectacular to north country skies during the April 8 eclipse. "Comet 12P is known for its dramatic outbursts, during which the ice ball loses a substantial amount of material, both ice that sublimates into gas and dust shed into the surrounding space," the Scientific American article reads. "This causes the comet to appear brighter by increasing the size of the fuzzy halo around it."

The comet, O'Donoghue said, is currently below the brightness observable by the human eye. "If the comet develops a tail, that may make it easier to spot, but it may be hard without binoculars," she said.

According to NASA, comet 12P is nicknamed "Devil Comet" for its hornlike appearance and that "fans of interstellar spaceflight have also suggested the distorted shape of this large comet's central coma looks like the Millennium Falcon" from "Star Wars." It last visited the inner solar system in 1954.

The comet was discovered in 1812 by Jean Louis Pons. It was rediscovered (confirmed) in 1883 by American William R. Brooks.