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An unusually prominent horned comet for a series of recent outbursts will be visible in the night sky for the rest of March – and astronomers expect the so-called devil comet to make a rare appearance during the total solar eclipse on 8 April.
Exactly why the dynamic comet takes a shape that has drawn comparisons to the Millennium Falcon spacecraft from the “Star Wars” movies while being explosively active is still an enigma to scientists. But the celestial object completes only one orbit around the sun every 71 years, like Halley’s Comet, making it a once-in-a-lifetime opportunity for close study.
Since the comet will not pass Earth again for years, the collective observations of astronomers could provide important insight into the true nature and behavior of Pons-Brooks.
Officially known as Comet 12P/Pons-Brooks, the celestial object will make its closest pass to the sun on April 21, coming within 74.4 million miles (119.7 million kilometers) of our star. The comet will then make its closest pass to Earth on June 2, but it will be 139.4 million miles (224.4 million kilometers) from our planet and pose no risk.
For those in the Northern Hemisphere, the last 10 days of March will provide the best view, according to Dr Paul Chodas, manager of the Center for the Study of Near-Earth Objects, and Davide Farnocchia, navigation engineer, at NASA’s Jet Propulsion Laboratory in . Pasadena, California.
“The comet will dim slightly as it gets closer to the sun, and should be visible to the naked eye low in the west about an hour after sunset,” according to a joint email from Chodas and Farnocchia. “You should go to a spot away from the city lights with an unobstructed view of the western horizon. It would be advisable to use a pair of binoculars, as it may be difficult to find the comet without them.”
After April 2, the comet is on track to move into the daytime sky and won’t be visible to sky watchers at night – but will be visible when the moon’s shadow blocks the face of the sun. temporary on April 8.
“The comet would be located about 25 degrees away from the eclipsed sun,” Chodas and Farnocchia said via email. “The comet should be easy enough to find during a total solar eclipse, as well as some planets, but the main focus during those 4 minutes should be on the eclipse itself!”
After the comet’s closest approach to the sun, known as perihelion, in late April the celestial body will move into the southern night sky and will only be visible to those in the Southern Hemisphere.
Two prolific inventors, Jean-Louis Pons and William Robert Brooksthe devil’s comet was first observed independently in 1812. But the comet probably made many trips around the sun over thousands of years, long before astronomers thought of comets as anything other than “something strange in the atmosphere ,” said Dr. Dave Schleicher, an astronomer at the Lowell Observatory in Arizona.
Astronomers estimate the giant comet to be between 6.2 and 12.4 miles (10 to 20 kilometers) in diameter, said astronomer Dr. Teddy Kareta, a postdoctoral associate at Lowell Observatory.
The dwarf visitor has a green appearance typical of most comets because they contain diatomic carbon molecules that absorb sunlight and emit a green color from our perspective, Schleicher said.
A series of cosmic outbreaks
Pons-Brooks recently caught the attention of astronomers after they showed interesting behavior that made the comet look like a horn as it ascends through our solar system.
The comet has had several outbursts over the past eight months, causing it to eject gas and dust. While such a release is not uncommon in comets and a crescent or Pac-Man shape has been observed in others, it is difficult to say what is normal for Pons-Brooks.
“I would say it’s somewhat unusual in terms of the number of hits he’s making,” Schleicher said. “On the other hand, you don’t seem to have good records from the past to tell you what is normal. And I suspect that, given the relatively large number of outbreaks that have occurred in the last eight months, this is clearly a normal occurrence for Pons-Brooks.”
Comets are blobs 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 heat up and brighten as they approach the sun, and some of the frozen gases stored in comets don’t need to heat up long before they begin to vaporize, Schleicher said.
“We think the ultimate driver is, of course, warming from the sun,” he said. “The comet is coming in; it has been sitting outside in a deep freeze for years. The heat will work its way from the surface down to wherever the carbon dioxide or carbon monoxide ice is located.”
Astronomers suspect that Pons-Brooks eruptions have occurred during the repeated events as heat vaporizes material within the comet, causing pressure to build up and break through the surface. Although a gas explosion would not be visible in telescopes, the dust it kicks off would create the type of events observed from Pons-Brooks, Schleicher said.
Scientists have traced the jets of material observed ejecting from the comet during its explosion to two source regions on its surface. Astronomers wonder why “the whole surface isn’t going crazy,” Schleicher said.
The observations suggest that the ice has crusted over most of the surface, or that the ice has evaporated, leaving only dirt behind, but the astronomers are “not quite sure which of these mechanisms that runs the show,” he said.
What we can learn from comets
A series of overlapping events likely contributed to Pons-Brooks’ distinctive appearance, but it could also be due to our perspective of the comet, Kareta said.
“These are three-dimensional objects,” Kareta said. “When we take images of the night sky, we’re taking them in a limited range of colors all flattened in two dimensions. This will make things that might make perfect sense to you, if you’re able to go up and walk around and see it in a few different perspectives, they’ll look a lot more complicated than they really are.”
The astronomers are looking at Pons-Brooks in the hope of getting more information about their rotation rate, or the rate at which comets spin as they move through space. Pons-Brooks has a rotation period of 57 hours, which is longer than expected, and astronomers are trying to determine whether jets of material ejected from the comet are speeding up or slowing down.
But Schleicher recommends keeping an eye on the comet now rather than during the eclipse.
“In all my years, I have seen many comets. I have only seen two total eclipses, and this will be No. 3. The first one I saw was back in 1991, from Baja. And that was just extraordinary. I remember realizing, no wonder this is considered the most amazing sight in the heavens that anyone on Earth can see. Go on the path and see it all. You don’t understand it until you’ve seen one.”
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