New Comet Swan 25B: From Behind The Sun

New Comet Swan 25B: From Behind The Sun

After emerging from hiding behind the Sun on Sept. 11, 2025, Comet SWAN25B is rapidly brightening. Multiple southern hemisphere observers on Sept 13th say it is near magnitude +6—that is, about three times brighter than the day before. Gerald Rhemann and Michael Jäger took this picture from Farm Tivoli, Namibia in southern Africa.

"This is a 12/5/5/5 min (LRGB) exposure through a 12-inch Astrograph," says Rhemann.

The comet has a green atmosphere and a long blue ion tail collimated by the solar wind. These colors are signs of C2 (green) and CO+ (blue)—compounds commonly found in Solar System comets.

The comet's orbit is still being determined. Initial astrometry suggests it has already passed through perihelion (closest approach to the sun). Next, it might make a close approach to Earth (0.25 AU) in October.

This weekend you can find Swan25B in the constellation Virgo not far from Mars and Spica. It is still close to the Sun, so be prepared to catch it near the horizon at sunset. 

Up-to-date coordinates may be found at the Minor Planet Center's Possible Comet Confirmation Page: 
https://minorplanetcenter.net/iau/NEO/pccp_tabular.html

Telescope: ASA Astrograph 12" f3.6 Camera: ZWO ASI 6200 MM Pro Mount: ASA DDM 85 Exp. Time: LRGB 12/5/5/5 min.

Image Credit: Gerald Rhemann, Michael Jäger
Gerald's website: https://www.astrostudio.at

Text Credit: Gerald Rhemann/SpaceWeather [dot] com

Release Date: Sept. 13, 2025

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