green flash sun April 2018 US
© Ronny TertnesThe Green Flash
Green flashes at sunset are rare. Indeed, they were once thought mythological. Blue flashes are rarer still. Yesterday, Ronny Tertnes of Bergen, Norway, saw them both in a single sunset:

"There was a visible green flash in the sunset on April 29th," says Tertnes. "But that's not all. Just before the green flash, there was a very blue glow visible along the sun's upper edge--even more blue than I managed to capture in the photo."

Green flashes are formed when the prismatic action of the atmosphere splits the setting sun into basic R-G-B colors. Temperature inversions create a mirage, magnifying the green into an eye-catching flash.

Blue flashes are formed in the same way, but they are rarely seen. Why? Because blue light is scattered strongly by molecules in the air. The same Rayleigh scattering that smears blue light around the daytime sky also disperses and mutes sunset blue flashes.

Tertnes saw it anyway. "It was a great sunset," he says.
The Blue Flash
© Ronny TertnesThe Blue Flash

Comment: Also reported by Space Weather was the moon's 'golden handle', a common occurrence and yet still awesome:


Once a month, about 4 days before the full Moon, the sun rises behind the Moon's towering Jura Mountains. For a few magic hours, sunlight dances along the mountain crest while the hardened lava plains below remain in darkness. These are the hours of the Golden Handle. Peter Lowenstein observed the phenomenon on April 26th from Mutare, Zimbabwe:

"I was lucky to catch it," says Lowenstein. "The night sky was perfectly clear when the crest of the Jura Mountains lit up, curving around the edge of Sinus Iridium (the Bay of Rainbows) to form the Golden Handle. This only happens when the Moon is about 11 days old."

The Golden Handle was famously depicted in Stanley Kubrick's 2001: a Space Odyssey when the lunar lander Aries departed en route to the Moon. It's next appearance is slated for May 25, 2018, when the sun rises again over Montes Jura. Lunar photographers, mark your calendar.

© Peter LowensteinThe golden handle (upper right side of the moon)
the golden handle the moon trees
Another shot of the golden handle