On August 7th, an unusual object flew past the sun. (Spoiler Alert: It's not an alien armada.) "It was a triple comet," says Karl Battams of the Naval Research Lab in Washington DC, who made this animation using coronagraph images from the Solar and Heliospheric Observatory (SOHO):
"The two main components are easy to spot, with the third, a very faint, diffuse fragment following alongside the leading piece," he says.
SOHO finds comets all the time. Most are Kreutz sungrazers, fragments of a giant comet that broke up more than 1000 years ago. Since the observatory was launched in 1995, SOHO has discovered more than 3000 members of the Kreutz family dive-bombing the sun.
And that's what makes this comet unusual. "It is not a member of the Kreutz family," says Battams. "Its orbit doesn't match. We're not yet sure where it came from."
Shortly after the comet cluster showed up in SOHO images, a rumor began to spread on social media: Spaceships are sling-shotting around the sun. "No," says Battams. "It's a comet. If it waddles like a duck, and quacks like a duck... chances are it's a duck! This object shows all the classic signs of being a comet: diffuse, elongated, has a tail, and follows a path that is clearly dominated by the sun's gravity."
The triple comet is now receding from the sun, fading rapidly from view. There's a slim chance that large ground-based telescopes might be able to track it. If so, they could find clues to its make-up and origin.
"Unfortunately, the prognosis for small fragmenting comets like this is not good," says Battams. "This was probably this comet's first and last pass by the sun, as it has likely now crumbled away entirely. But SOHO will continue to keep watching the sun, and waiting for our next special cometary offering to come along."
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