The Blue Ozone Fringe: A Rare Glimpse During the September 2025 Total Lunar Eclipse
A truly breathtaking sight was captured during the total lunar eclipse of September 7, 2025. From Damavand, Iran, astrophotographer Saeed Anvaar managed to document a rare and fascinating phenomenon: a delicate turquoise band gracing the edge of the Moon's umbra.
What is the Blue Ozone Fringe?
As the Moon emerged from totality at approximately 22:25 IRST, approximately 40 degrees above the horizon, a thin, vibrant turquoise line became visible along the inner edge of Earth's umbra. This captivating display is a direct result of Chappuis absorption bands, a phenomenon occurring when sunlight is refracted through the ozone layer in Earth's upper atmosphere.
In contrast, the characteristic reddish hue of the umbra itself is caused by Rayleigh scattering. This process preferentially removes shorter, bluer wavelengths of sunlight, allowing the longer, redder wavelengths to pass through and illuminate the Moon.
Capturing the Magic
This incredible image was achieved using a Canon 6D (unmodified) DSLR mounted on a 10-inch SkyWatcher Dobsonian GoTo telescope. The photographer utilized an ISO of 200 for all exposures.
The final composite is a masterful blend of five individual frames, capturing a range of exposures from 0.5 seconds down to 1/3200 seconds. These frames were meticulously aligned on lunar surface features and then blended using luminance masks. This technique allowed for the preservation of detail across both the bright and dark areas of the Moon, while the final color balance was carefully calibrated to accentuate the striking turquoise ozone fringe and the deep red glow of the umbra.
A Celestial Poké Ball?
Many viewers have noted the uncanny resemblance of this celestial event to a Poké Ball – the iconic item from the Pokémon franchise. Once you see it, it's hard to unsee! This unique perspective adds another layer of wonder to an already magnificent astronomical event.
This observation serves as a beautiful reminder of the intricate and dynamic interplay between Earth's atmosphere and the celestial bodies we observe.
