MASSIVE SAR ARC SIGHTED: "This weekend's geomagnetic storm caused a bright SAR arc that was seen from the USA to Europe," reports Jeff Baumgardner of Boston University's Center for Space Physics. "It nearly saturated our detector and may have been visible to the un-aided eye on Oct. 19th around 0200 UTC. Only a few times in a solar cycle do we get one this bright." Readers: Did you photograph this SAR arc? Submit your photos here.
COMET LEMMON AND THE GEOMAGNETIC STORM: An overdue CME passed near Earth during the late hours of Oct. 17th. The near-miss produced an unexpected photo-op. Auroras swallowed Comet Lemmon (C/2025 A6):
Alan C. Tough captured the event from Elgin, Moray, Scotland. "I set up a star tracker with a DSLR and 150mm lens in my back garden to photograph Comet Lemmon when the auroras erupted," he says.
The CME was expected to reach Earth two days earlier. Better late than never. It sparked a G1/G2-class storm with auroras sighted in the USA as far south as New York and Utah.
In the Czech Republic, Petr Horálek observed the effect of the solar wind on the comet itself:
"This was a truly unusual view," Horálek says. "During the storm, the comet over Seč Lake was surrounded by red auroras. When I zoomed in on the comet, I could see its ion tail was twisted by the buffeting of the solar wind."
The storm is over, but the comet is still there. In fact, it's about to make its closest approach to Earth, only 0.6 AU away on Oct. 21st. Shining at 4th magnitude, it will be visible to the naked eye and even cell phones (with night-sky photo settings) should be able to catch it. Point your optics low in the northwestern sky after sunset. Sky maps: Oct. 19, 20, 21.
more images: from Lauri Kangas of Amethyst Bay, Lake Superior, Ontario; from P-M Hedén of Norrtälje, Sweden; from Patrick Lecureuil of Mauroux, France
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DARK MATTER COINS FROM SPACE: These coins are not actually made of Dark Matter, but they are inscribed with the words "Dark Matter" -- and you can spend them. The US Mint has created a series of quarters honoring astronomer Vera Rubin, who discovered dark matter in galaxies. On Sept. 6, 2025, the students of Earth to Sky Calculus flew them to the edge of space:
You can have two unbroken rolls for $199.95. The coin's design features a profile of Dr. Vera Rubin gazing upward, smiling as she contemplates the cosmos. She is surrounded by a spiral galaxy and other celestial bodies.
One of the rolls is D Mint, the other P Mint, so you'll have a complete set. You'll also receive a greeting card showing the coins in flight and telling the story of its journey to the edge of space.
Don't need a whole roll? You can buy a single coin for only $39.95.
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COMET SWAN AND THE EAGLE NEBULA: "From the Southern Hemisphere, Comet Lemmon is out of sight, but another, almost forgotten comet is currently crossing the Milky Way," says astronomer Daniele Gasparri of Atacama, Chile. "Here is Comet SWAN (C/2025 R2) passing through one of the most iconic and spectacular regions of the sky: the Eagle Nebula."
The Eagle Nebula (M16) is a young star cluster located 5,700 light-years away in the constellation Serpens. It is home to the famous "Pillars of Creation."
"At 6th magnitude, Comet SWAN is visible to the naked eye under the pristine skies of the Atacama Desert," adds Gasparri. "It was also an amazing sight through the eyepiece, with its characteristic green coma drifting across one of the most observed nebulae in the sky."
Coincidentally, Comet SWAN is making a close approach to Earth on Oct. 20th, only one day before Comet Lemmon does the same thing. This gives photographers a double photo-op this week. Look for Comet SWAN near the constellation Sagittarius after sunset. Sky maps: Oct. 19, 20, 21.
more images: from Chris Schur of Payson, Arizona; from Jeremy Perez at Robinson Crater, Arizona; from Rolando Ligustri using a remote telescope in Namibia
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