AURORAS LOVE EQUINOXES: The northern autumnal equinox is only two weeks away. That's good news for sky watchers because auroras love equinoxes. Researchers call it the "Russell-McPherron effect." At this time of year, cracks form in Earth's magnetic field. Even a weak stream of solar wind can penetrate to spark a good display. Let Fall begin! Aurora alerts: SMS Text.
INTERSTELLAR COMET IMAGED DURING LUNAR ECLIPSE: On Sept 7th, darkness fell across the Kalahari Desert as Earth's shadow enveloped the full Moon. It was a total lunar eclipse--and the perfect time to photograph an interstellar comet. "We took advantage of the total lunar eclipse to take a deep image of Comet 3I/ATLAS under the dark skies of Namibia," says amateur astronomers Michael Jäger and Gerald Rhemann. Here is what they saw:
The comet was green. "Our images show a gas-rich coma of 2 arcminutes for the first time," says Jäger "It was clearly visible in both the blue and green filters."
The sight is familiar to astronomers: Comets in our own Solar System often glow green. Their emerald hue comes from diatomic carbon (C2), which fluoresces at 518 nanometers when energized by sunlight.
Is that why 3I/ATLAS is green? The jury's still out. In August, spectroscopy by astronomers at Kitt Peak showed that 3I/ATLAS was strongly depleted in C2. Indeed, it was one of the most carbon-chain poor comets ever observed. Perhaps C2 production turned on in September. Or the green glow might come from some other mix of gases or dust, mimicking a classic cometary color with unfamiliar chemistry.
Stay tuned for updates. Its passage is far from over. Each week could bring new chemistry from another star system.
more images: from Efrain Morales of Aguadilla, Puerto Rico
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SOLAR SYSTEM EARRINGS FROM SPACE: These earrings have flown to the edge of space--and all eight planets are included! On May 21, 2025, the students of Earth to Sky Calculus launched the Solar System Stud Earrings to the stratosphere onboard a cosmic ray research balloon. At the apex of the flight, they floated 104,655 feet high:
You can have the complete set for $99.95. Only Pluto is omitted from the collection; the dwarf planet was too small for human earlobes. The earrings come with a greeting card showing the studs in flight and telling the story of their journey to the stratosphere and back again.
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