Watch the largest comet burst of all time spray dust across the cosmos
The dust trail from the biggest comet burst ever seen will grace the sky this summer — and look like a giant hourglass.
The night’s show will be thanks to Comet 17P/Holmes, which emitted a massive burst of gas and dust in October 2007, brightened by a factor of a million and briefly became Earth’s largest object solar system. In that short time, its coma, the cloud of dust surrounding the comet’s body, was larger in diameter than The sun.
At first, it seemed like the particles emitted in this record-breaking burst would simply disperse in space, Maria Gritsevich, a planetary scientist at the University of Helsinki in Finland, told Live Science.
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Now, a new model of the comet’s dust trail, described in a study by Gritsevich and her colleagues, finds that the dust trail persisted instead. Particles left by the eruption travel in an elliptical orbit between the original eruption point and a point on the opposite side of the dust trail’s journey around the sun, visible from the southern hemisphere.
In 2022, the particles will start accumulating again near the eruption point, meaning the dust trail will be visible from the northern hemisphere, even for amateur stargazers.
“Now telescopes are so good that any relatively modest system can do it,” the study’s lead author Gritsevich told Live Science.
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Comet 17P/Holmes orbits between Mars and Jupiter. English astronomer Edwin Holmes first spotted it in 1892 when it flared up with a flare large enough to catch his attention while he was observing the Andromeda galaxy. The 2007 eruption was even bigger.
“Other comets in similar orbits around the Sun don’t produce these kinds of large periodic outbursts, so 17P/Holmes itself is probably special,” wrote Markku Nissinen, co-author of the study, an astronomer with Finland’s Ursa Astronomical Association, in one Live Science Email.
No one knows exactly how the comet produces such dramatic outbursts, but they can occur when subsurface ice in the comet’s body transitions from a disorganized amorphous arrangement to a structured crystalline arrangement. This transition releases gas from the ice and creates an outward pressure on the comet’s surface. The result is an eruption of ice, gas, and dust. (That this happens without blowing the comet to pieces is “remarkable,” Nissinen noted.)
In the new study, published in Monthly Bulletins of the Royal Astronomical Society (opens in new tab)the researchers modeled the physics of the dust trail to understand how its original shape led to the orbit observed today.
Combining observations from the Northern and Southern Hemispheres with an understanding of how heaviness and the solar wind act on particles of different sizes, the researchers tracked the path of the dust trail over time. During their journey, the particles sort themselves by size due to the effects of gravity and solar wind, generally reaching the two nodes in their orbit in the order medium, large, and small. The dust also moves in a subtle hourglass shape, with two dust bulges on either side and a narrowed dust zone in the middle, a relic of the comet’s body’s initial spherical dust outburst.
The particles are tiny, up to fractions of a millimeter in size, but reflect the sun’s light and, with the help of a telescope, make them visible as a blurred trail in the night sky. (The trail has been visible before, including from the Northern Hemisphere in 2014 and 2015, but its brightness varies depending on how the particles capture the Sun.) There was already a report from an amateur astronomer in Finland taking photos of the Spur made in February and March, said Gritsevich. Other Northern Hemisphere observers will have an opportunity to search for the trail in late July or later once the particles emerge from the harsh sunlight, Nissinen said. The point of convergence where the particles gather is in the Constellation Pegasus.
Modeling the dust trail could one day help astronomers study comets up close and personal, Gritsevich said. With an accurate map of where the comet’s dust is, scientists could launch spacecraft to collect material, which is easier than intercepting and sampling the comet itself. She and her colleagues now plan to model the dust trail from the original 1892 eruption in hopes of finding the dust from that event.
The comet hasn’t seen an eruption since 2007, and it’s impossible to say when the next eruption will come, Nissinen said. 17P/Holmes triggered consecutive eruptions in 1892 and 1893, so it can erupt at any time. The comet will swing closest to the sun again on January 31, 2028.
Originally published on Live Science (opens in new tab)
https://www.space.com/comet-17p-holmes-dust-trail Watch the largest comet burst of all time spray dust across the cosmos