![\"Rapid](\"https:\/\/www.europesays.com\/us\/wp-content\/uploads\/2025\/11\/rapid-brightening-of-i.jpg\" "\\"Left:")
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Left: Stack of all CCOR-1 frames of 3I\/ATLAS (top), and an equivalent stack centered on a nearby star on the same frames, approximating the PSF (bottom). Right: Similar stacks of all HI1 (top), COR2 (middle), and LASCO C3 Clear (bottom) frames of 3I. All stacks are aligned with north up. The heliocentric velocity (+v), and sunward (\u2299) or antisunward (\u2212\u2299) directions are labeled for the comet at the midpoint time. Credit: arXiv (2025). DOI: 10.48550\/arxiv.2510.25035<\/p>\n
An interstellar comet that originated outside our solar system has just made its closest pass to the sun, brightening dramatically and rapidly as it did so. The reason for the sudden extreme activity is currently puzzling scientists.<\/p>\n
\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\tA stranger in the neighborhood<\/p>\n
The latest visitor to our corner of the galaxy was first spotted on July 1, 2025, by astronomers and officially named comet<\/a> 3I\/ATLAS. It’s only the third interstellar comet ever recorded and was calculated to be on a course that would take it close to the sun without plunging into it.<\/p>\n As the object neared its closest point to our star (perihelion), the immense solar glare made it virtually impossible for Earth-based telescopes to see it. So astronomers turned to space-based solar observatories like SOHO, STEREO-A and GOES-19 to keep a watchful eye.<\/p>\n In a paper published<\/a> on the arXiv preprint server, researchers confirmed that as the comet closed in on the sun, it was brightening at a steeply accelerating rate. This surge was more extreme than had ever been observed in a comet before. These icy bodies usually brighten slowly as they heat up. The comet also appeared blue, which surprised scientists as comets are typically red owing to dust reflecting sunlight.<\/p>\n “Our cursory analysis of this data indicates the comet will likely emerge from conjunction considerably brighter than when it entered, with an extrapolated geocentric V magnitude of \u223c9 at perihelion, perhaps driven by prominent, visible gas emission,” wrote the researchers in their paper.<\/p>\n \t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\tSearching for answers<\/p>\n While the causes of the comet’s extreme behavior are puzzling, the study’s authors propose a few possible reasons. First, the brightening could have been caused by a massive surge of gas emanating from the comet. This is supported by the fact that the gas’s light was blue and strong enough to overpower the dust’s reflection. The color is a tell-tale sign of molecules like carbon glowing intensely when heated by the sun.<\/p>\n Another reason could be 3I\/ATLAS’s unique composition. The researchers found that its chemical composition<\/a> differs from that of comets in our solar system<\/a>. For example, there is a higher carbon dioxide content, more volatile ices (which could explain gas surges), and unusual metals.<\/p>\n We may not have any definitive answers yet, but there will be other opportunities to study this unusual comet. As it moves away from the sun, ground-based telescopes<\/a> can take over for more detailed studies.<\/p>\n \n Written for you by our author Paul Arnold<\/a>, edited by Gaby Clark<\/a>, and fact-checked and reviewed by Robert Egan<\/a>\u2014this article is the result of careful human work. We rely on readers like you to keep independent science journalism alive. More information:<\/strong> \n\t\t\t\t\t\t\t\t\t\t\t\t\tJournal information:<\/strong> \t\t\t\t\t\t\t\t\t\t\t\t\t\t<\/a>\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<\/p>\n \n\t\t\t\t\t\t\t\t\t\t\t\t \u00a9 2025 Science X Network\n\t\t\t\t\t\t\t\t\t\t\t <\/p>\n \n\t\t\t\t\t\t\t\t\t\t\t\tCitation<\/strong>: \n\t\t\t\t\t\t\t\t\t\t\t This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no
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\n\t\t\t\t\t\t\t\t\t\t\t\tQicheng Zhang et al, Rapid Brightening of 3I\/ATLAS Ahead of Perihelion, arXiv (2025). DOI: 10.48550\/arxiv.2510.25035<\/a><\/p>\n
\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\tarXiv<\/a>
\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t<\/p>\n
\n\t\t\t\t\t\t\t\t\t\t\t\tRapid brightening of interstellar comet 3I\/ATLAS as it nears sun surprises scientists (2025, October 31)
\n\t\t\t\t\t\t\t\t\t\t\t\tretrieved 1 November 2025
\n\t\t\t\t\t\t\t\t\t\t\t\tfrom https:\/\/phys.org\/news\/2025-10-rapid-brightening-interstellar-comet-3iatlas.html\n\t\t\t\t\t\t\t\t\t\t\t <\/p>\n
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