GEOMAGNETIC STORM WATCH--CANCELED: Sept. 26 has passed without another CME impact. Thus the geomagnetc storm watch is cancelled. Earth's magnetic field should continue to calm on Sept. 27th as lingering effects from the Sept. 24th CME impact subside. Aurora alerts: SMS Text
COMET NISHIMURA VS. THE SUN: This month, Comet Nishimura (C/2023 P1) is passing by the sun inside the orbit of Mercury. The Heliospheric Imager on NASA's STEREO-A spacecraft has gotten some great footage of the close encounter:
"Comet Nishimura is looking spectacular!" says Karl Battams of the Naval Research Laboratory, who made the movie. "There are lots of beautiful interactions between the comet tail and the solar wind, along with a possible glancing blow from a CME."
The other bright object in the field of view is Mars. Although the comet and the planet seem to be close together (especially on Sept. 23rd), they are in fact very far apart. Mars is on the far side of the sun hundreds of millions of kilometers away.
The comet will remain in STEREO-A's field of view until Oct. 3rd, and Battams plans to make new movies every day. Stay tuned for more CME strikes to Nishimura.
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RARE RED AURORAS (UPDATED): As predicted, a CME hit Earth's magnetic field on Sept. 24th (2043 UT). The impact was much stronger than expected. Magnetometer needles in Canada jerked by as much as 129 nT, and a G2-class geomagnetic storm began almost immediately after the CME arrived. Observers in Europe saw rare red auroras as far south as France:
"What a wonderful red aurora we had last night night in France!" says photographer Nicolas Drouhin of Burgundy. "It did not last long (about 5 minutes), but it was intense, even to the naked eye!"
Naked-eye sightings of red auroras are unusual because human eyes are notoriously insensitive to the 6300 Å wavelength of their red light. Yet multiple observers in, e.g., Scotland and Iceland confirmed that they saw the scarlet glow.
Later, the storm crossed the Atlantic and brought the same red colors to North America:
"These amazing red auroras were all over the sky," says Ayumi Bakken, who took the picture just outside Fairbanks, Alaska. The farthest south they were photographed was Curtis, Nebraska (latitude +40.6N) and Burlington, Kansas (+38.2N).
Why are red auroras rare? Partly it's just that we have trouble seeing them, so they go unreported by sky watchers. Mainly, though, it's because they are the most delicate kind of auroras. Red auroras come from atomic oxygen near the top of Earth's atmosphere. Oxygen atoms excited by solar wind or a CME spit out their red photons very slowly. The radiative lifetime of the transition is 110 seconds--an eternity in the quantum realm. The atoms must remain undisturbed that long to produce their eerie red light.
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SOLAR ECLIPSE PENDANT: The students of Earth to Sky Calculus are about to try something never done before--to photograph the shadow of an annular solar eclipse from the stratosphere. On Oct. 14th, they'll launch a cosmic ray research balloon equipped with cameras to photograph the shadow zone of an eclipse over Nevada. You can support the flight by buying a Solar Eclipse Pendant:
It's yours for $99.95. The students launched this pendant on July 17th. Floating at an altitude 105,000 feet above Earth’s surface, it made contact with space, experiencing temperatures as low as -63 C.
Buy the pendent now and for no additional charge we will fly it back to the stratosphere during the annular eclipse. Just make a note in the COMMENTS BOX of your shopping cart: "Fly my pendant again!"
Note: We have photographed the shadow of an eclipse before. Here's what the total eclipse of Aug. 21, 2017, looked like from the stratosphere over the Nebraska-Wyoming border:
Total eclipses make deep black shadows, in this case blacking out more than 70 miles of terrain. What does the shadow of an *annular* eclipse look like? We hope to find out. It should be fuzzier around the edges, and not nearly as dark in the middle. An overview from the stratosphere could provide a unique picture.
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