The dust trail from the biggest comet explosion ever seen will grace the skies this summer – and it will look like a giant hourglass.
The nightly spectacle will be courtesy of Comet 17P/Holmes, which in October 2007 released a massive flash of gas and dust, brightening by a factor of a million and briefly becoming the world’s largest object. solar system. During this brief period, its coma, the cloud of dust surrounding the body of the comet, had a diameter larger than the sun.
At first, it looked like the particles emitted in this record-breaking explosion might just scatter into space, Maria Gritsevich, a planetary scientist at the University of Helsinki in Finland, told Live Science.
Now, a new model of the comet’s dust trail, described in a study by Gritsevich and colleagues, finds that the dust trail has instead persisted. Particles left by the explosion zing in an elliptical orbit between the point of origin of the explosion and a point opposite the path of the dust trail around the sun, visible from the southern hemisphere.
By 2022, the particles are once again accumulating near the point of explosion, meaning the dust trail will be visible from the northern hemisphere, even to amateur astronomers.
“Now telescopes are so good that any relatively modest system will do,” lead study author Gritsevich told Live Science.
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Comet 17P/Holmes orbits between Mars and Jupiter. English astronomer Edwin Holmes first discovered it in 1892, when it erupted with an explosion large enough to catch his attention as he observed the Andromeda Galaxy. The explosion of 2007 was even bigger.
“Other comets in similar orbits around the Sun don’t produce these kinds of periodic large outbursts, so 17P/Holmes itself is likely special,” wrote study co-author Markku Nissinen, an astronomer from the Finnish Astronomical Association Ursa, in an email. to living science.
No one knows exactly how the comet produces such dramatic explosions, but they may occur when the subterranean ice in the comet’s body changes from a disorganized amorphous arrangement to a structured crystalline arrangement. This transition releases gas from within the ice, creating outward pressure on the comet’s surface. The result is an eruption of ice, gas and dust. (That this happened without blasting the comet to pieces is “remarkable,” Nissinen noted.)
In the new study published in the Royal Astronomical Society Monthly Noticesthe researchers modeled the physics of the dust trail to understand how its initial shape led to the orbit observed today.
Combining observations from the northern and southern hemispheres with an understanding of how gravity and the solar wind acting on particles of different sizes, the researchers traced the path of the dust trail over time. As they travel, the particles sort themselves out by size due to the effects of gravity and the solar wind, typically arriving at both nodes of their orbit in the order medium, large, and small. The dust also moves in a subtle hourglass shape, with two bulges of dust on each side and a constricted area of dust in the middle, a relic of the initial spherical burst of dust from the comet’s body.
The particles are tiny, down to fractions of a millimeter, but they reflect sunlight, making them visible through a telescope as a blurry trail in the night sky. (The contrail has been visible before, including from the northern hemisphere in 2014 and 2015, but its brightness varies depending on how the particles catch the sun.) There was already a report from an amateur astronomer in Finland who took photos of the trail in February and March, Gritsevich said. Other northern hemisphere observers will have the opportunity to search for the trail in late July or later, once the particles have emerged from the sun’s glare, Nissinen said. The point of convergence where the particles come together is in the pegasus constellation.
Dust trail modeling could help astronomers one day study comets up close and personal, Gritsevich said. With an accurate map of where the comet’s dust is, scientists could launch a spacecraft to collect material, an easier proposition than intercepting and sampling the comet itself. She and her colleagues now plan to model the dust trail from the original 1892 explosion in hopes of finding dust from that event.
The comet hasn’t seen an explosion since 2007, and it’s impossible to say when the next explosion will occur, Nissinen said. 17P/Holmes set off consecutive explosions in 1892 and 1893, so it is capable of erupting at any time. The comet will swing closest to the sun again on January 31, 2028.
Originally posted on Live Science