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Nicknamed the “Devil’s Comet,” the unusual horned comet notable for its series of explosions will make its closest approach to Earth on Sunday around 3 a.m. ET.
While the comet has not been visible to those in the Northern Hemisphere since the first week of May, sky watchers in the Southern Hemisphere have a better chance of spotting the blurry object through binoculars or binoculars.
Exactly why the dynamic comet takes on the shape of the Millennium Falcon from the “Star Wars” movies when it is explosively active is still a mystery to scientists. However, the celestial object only completes one orbit around the Sun approximately every 71 years, similar to Halley’s Comet, making the likelihood of observing it for closer study a once-in-a-lifetime opportunity.
Since the comet will not pass by Earth again for decades, astronomers’ collective observations could provide key insights into its true nature and behavior.
The celestial object, officially known as Comet 12P/Pons-Brooks, made its closest flyby of the Sun on April 21, coming within 74.4 million miles (119.7 million kilometers) of our star.
The comet will make its closest pass by Earth on Sunday, but will be more than 230 million kilometers from our planet and pose no risk. By comparison, the Sun is 93 million miles (149 million kilometers) from Earth.
The comet peaked in brightness in late April and has been steadily dimming for three to four weeks, said Dr. Dave Schleicher, an astronomer at the Lowell Observatory in Arizona.
“For people down below the equator, the coming weeks and months may be their first good chance to see this thing since the 1950s,” said astronomer Dr. Teddy Kareta, a postdoctoral fellow at Lowell.
Two prolific discoverers, Jean-Louis Pons and William Robert Brooks, independently observed Devil’s Comet—Pons in 1812 and Brooks in 1883. But the comet probably made many trips around the Sun over thousands of years, long before astronomers thought of comets like comets. anything other than “something weird in the atmosphere,” Schleicher said.
Astronomers estimate the massive comet to be between 6.2 to 12.4 miles (10 to 20 kilometers) in diameter, Kareta said.
The rare visitor has the green appearance typical of most comets because they contain diatomic carbon molecules that absorb sunlight and emit a color that appears green from our perspective, Schleicher said.
Pons-Brooks recently caught the attention of astronomers after it exhibited an interesting behavior that caused the comet to take on a horned appearance as it soared through our solar system.
The comet has experienced a series of explosions over the past eight months, ejecting gas and dust. While such escapes are not uncommon in comets, and others have been observed to be crescent or Pac-Man shaped, it is hard to say what is normal for Pons-Brooks.
“I would say it’s somewhat unusual in the number of flares it has,” Schleicher said. “On the other hand, it’s not like you have good records from the past to know what’s typical. And I suspect that, given the relatively large number of explosions that have occurred over the last eight months, this is quite clearly a regular occurrence at Pons-Brooks.”
Comets are chunks of dust, rock, and ice, essentially frozen remnants from the formation of the solar system. They also contain frozen elements such as carbon dioxide and carbon monoxide.
Comets get hotter and brighter as they get closer to the Sun, and some of the frozen gases stored in comets don’t need to heat up very much before they start to turn into vapor, Schleicher said.
“We think the main rider is obviously being warmed by the sun,” he said. “The comet is coming; it’s been lying in the deep freeze for years. The heat will spread from the surface down to where the carbon dioxide or carbon monoxide is.”
Astronomers hypothesize that Pons-Brooks explosions occur in the course of repeated events, as heat vaporizes material inside the comet, causing pressure to build up and penetrate the surface. While the gas explosion would not be visible in telescopes, the dust it shoots up would create the type of events observed from Pons-Brooks, Schleicher said.
The researchers traced the jets of material observed being released from the comet during its explosion to two source regions on its surface. Astronomers are puzzled as to why “the whole surface doesn’t look crazy,” Schleicher said.
The observations suggest that the ice crusted over most of the surface, or the ice evaporated, leaving only clay, but astronomers “are not entirely sure which of these mechanisms is running the show,” he said.
However, the comet appears to have stopped bursting and has not shown any burst activity since February, Kareta said.
Astronomers observed Pons-Brooks in the hope of revealing more details about the spin rate, or rate of rotation, of comets as they move through space. Pons-Brooks has a rotation period of 57 hours, which is longer than expected, and astronomers want to know whether jets of material released from the comet speed it up or slow it down.
An overlapping series of events likely contributed to Pons-Brooks’ distinctive appearance, but it could also be due to our perspective of the comet, Kareta said.
“They’re three-dimensional objects,” Kareta said. “When we take pictures of the night sky, we take them in a limited range of colors, all flattened in two dimensions. It makes things that might make perfect sense to you if you’re able to go up and walk around and see it from a few different perspectives look a lot more complicated than they really are.”