No tricks, but skywatchers may be in for an October treat when a newly discovered comet passes through our skies. Comet C/2025 R2 (SWAN) — or SWAN25B for short — looks to be heading our way.
The comet — named after the science instrument aboard the SOHO space observatory, which observes the sun — was first spotted on Sept. 11 by Ukrainian amateur astronomer Vladimir Bezugly, while studying images captured by SWAN.
“This is a milestone, the 20th official SWAN comet so far,” Bezugly told Universe Today.
Read more: 7 Stargazing Apps for Spotting Constellations and More
Bezugly made the discovery one day before the comet reached its closest point to the sun, which is known as perihelion.
“It was an easy comet for detection due to sufficient brightness in the (ultraviolet) band and location in the SWAN images, exactly in its center,” Bezugly told Universe Today. “But it was difficult due to the very close location to the sun and angular motion, which is very close to the sun’s motion in SWAN images.”
On Sept. 17, an observatory in Chile snapped a photograph using a telescope, showing SWAN25B with a bright coma and striking emerald ion tail. A coma is an atmosphere that forms around a comet as it nears the sun. The sun’s heat causes the frozen gases and icy chunks in the comet’s nucleus to change and create an atmosphere.
“With its orbit still poorly constrained due to a very short observational arc, this comet has quickly become a fascinating target to follow in the coming weeks,” the team in Chile said.
What exactly is a comet?
NASA calls comets “cosmic snowballs of frozen gases, rock, and dust that orbit the sun,” noting that “when frozen, they are the size of a small town.”
Their most famous comet feature is probably the tail. When comets come near the sun, they heat up and spew dust and gases, forming the tail, which streams away from the sun. NASA says there are likely billions of comets orbiting our sun.
The most famous comet is Halley’s comet, which appears every 76 years. It was last seen in Earth’s skies in 1986 and will return in 2061.
When should I look for the new comet?
According to LiveScience, the comet should pass closest to Earth around Oct. 19-20, and some astronomers think it could be bright enough to observe without a telescope or binoculars. Look for a faint, fuzzy patch of light. A smartphone app can help you find it.
You can track the position of SWAN25B using TheSkyLive.com, which gives the comet’s distance from the Earth in real time and offers a neat interactive star map. That map lets you enter your location so you can see what the sky looks like from where you live.
It’s much easier to see the comet, or any cosmic features in the night sky, if you head away from city lights and go to a dark area in the country. Try to find a clear night, when the clouds won’t impact visibility. SWAN25B might be bright enough to observe by looking up in the sky.
More skygazing highlights
October is already a busy month for skywatchers.
A supermoon will hang in the night sky bigger and brighter than usual during its perigee, and a great time to head outside to see it is Oct. 6, when there’s a full moon. The October supermoon will be the first of four consecutive supermoons, which we can expect every month through January of next year.
If you’re looking for help to guide your skywatching this October, head to our list of Best Stargazing Apps.
