A LULL IN SUNSPOT ACTIVITY: In the past two weeks, sunspot counts have sharply dropped, leaving the solar disk almost blank. Does this mean Solar Cycle 25 is ending prematurely? No. "Sunspot lulls" are normal statistical fluctuations observed during even very strong solar cycles. Almost certainly, Solar Cycle 25 will bounce back soon as it heads for a maximum in 2024-25. Solar flare alerts: SMS Text
THE MYSTERY OF ORANGE AURORAS: A recent display of auroras over Canada has experts scratching their heads. The mystery? They were orange:
"This was a first for me," says Harlan Thomas, who photographed the display over Sibbald Pond west of Calgary, Alberta, on Oct. 19th. "The orange was sublime, just incredible. The pillars in the center stayed there glowing for more than 20 minutes."
Auroras aren't supposed to be orange. Consider the following: Auroras get their colors from atoms and molecules in Earth's atmosphere. During geomagnetic storms, energetic particles rain down from space, striking the air and causing it to glow. Red, green, purple and even pink are common signs of excited oxygen and nitrogen.
The problem is, there's nothing in the air capable of making bright orange. Theoretically, nitrogen and oxygen (N2, N2+, and O2+) can produce emissions at orange wavelengths. However, these emissions are very weak compared to other colors produced by the same molecules. Any orange should be overwhelmed.
Aurora colors produced by atoms and molecules in Earth's atmosphere. [more]
The answer may be hiding in plain sight. Take another look at Thomas's photo. Bright red auroras appear on top, overlapping green auroras lower down. Red and green mixing together may have produced the yellow-orange glow.
Indeed, aurora physicist Kjellmar Oksavik of the University of Bergen in Norway believes that's the correct explanation:
"Red auroras are formed by low-energy electrons colliding with atomic oxygen at high altitudes (200-400 km). Here, oxygen atoms are excited into a quantum state called O(1D), where they can emit a red photon at 630.0 nanometers," Oksavik says.
"Green auroras are formed by higher-energy electrons penetrating deeper and colliding with atomic oxygen at lower altitudes (100-150 km)," he continues. "Here, oxygen atoms are excited into a state called O(1S), where they emit a green photon at 557.7 nanometers."
"In between, there can be a mixing of the two processes, which fools the camera and eye to believe that it is orange. In reality, it is both red and green at the same time," he says.
More examples of orange recorded during the Halloween Storms of 2003. Credit: Jay Edwards.
Oksavik points out one more thing in Harlan Thomas's photo: "It beautifully reveals the alignment of Earth’s magnetic field. The bright pillar in the center is a textbook example of a very tall auroral ray. These are aligned along the magnetic field and caused by a broad energy spectrum of electrons [raining down from space]. Slower electrons collide high up (red light), while more energetic electrons travel further down into a much denser atmosphere (green light)." The overlap naturally produces a yellow-orange glow--no mystery molecule required.
Have you photographed an orange aurora? Submit your pictures here.
more orange: from Louis Greene in Denali National Park, AK; from Doug McAvoy of Commanda, Ontario, Canada; from Raymond Maher of Maurice River Township, New Jersey; from Serian Kallweit of Baksjöbodarna, Sweden
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HANDMADE ANNULAR SOLAR ECLIPSE PENDANT: This pendant has touched the shadow of the Moon. The students of Earth to Sky Calculus launched it to the stratosphere on Oct. 14, 2023, during the annular solar eclipse. The handmade pendant was 78,500 feet high when the Moon's shadow arrived and wrapped it in a cool twilight-like darkness:
You can have it for $129.95. The pendant left Earth from Nevada's Valley of the Moon, a remote area filled with the scent of sage and herds of wild horses. Indeed, no fewer than three mustang families approached the launch team during the eclipse to see what was going on. It was a magical experience.
The students are selling space pendants to pay the helium bill for their cosmic ray ballooning program. Each one comes with a greeting card showing the jewelry in flight and telling the story of its trip to the stratosphere and back again.
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