Astronomy Picture of the Day 11-10-02

NASA ^ | 11-10-02 | Robert Nemiroff and Jerry Bonnell

[petuniasevan]

Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2002 November 10

A Green Flash from the Sun
Credit & Copyright: Pekka Parviainen (Polar Image)

Explanation: Many think it is just a myth. Others think it is true but its cause isn't known. Adventurers pride themselves on having seen it. It's a green flash from the Sun. The truth is the green flash does exist and its cause is well understood. Just as the setting Sun disappears completely from view, a last glimmer appears startlingly green. The effect is typically visible only from locations with a low, distant horizon, and lasts just a few seconds. A green flash is also visible for a rising Sun, but takes better timing to spot. A dramatic green flash was caught in the above photograph in 1992 from Finland. The Sun itself does not turn partly green, the effect is caused by layers of the Earth's atmosphere acting like a prism.

[petuniasevan]

I grew up in Southern California and saw this intriguing phenomenon several times. Each time I was at the beach, except for once I was in the San Gabriel Mountains near Mt. Wilson.

Has anyone else at FR seen the green flash?

[petuniasevan]

[EggsAckley]

Yes yes.....I HAVE seen it. It was in Cleone, north of Fort Bragg CA. It was August, about six or seven years ago. The next night, at sunset, I was armed with a camera and ready, but it didn't happen again. Drat!!


Great pic. Thanks.

[RadioAstronomer]

I never have, but would love to. :-)

[RightWhale]

The green flash requires strong atmospheric refraction. It can be seen from Prudhoe Bay in the Spring and in the Fall, but it doesn't happen every time the sun sets or rises.

Note that in the picture, the green flash is not the sun itself, but a refracted image, a mirage. The sun has already set, but the mirage hovers above the horizon and refracts into the green portion of the spectrum.

On March 21 several years ago at Prudhoe Bay I sat in the cab of a truck and watched the sun set at 6PM, which happens at that time everywhere around the world on that date. Due to refraction at that latitude, the mirage image of the sun didn't set, but continued to move around the horizon to the north for 3 hours. About 9PM the mirage finally dimmed and winked out, but no green flash. The image wasn't round at all, but an elongated rectangle, growing flatter as it moved north at a constant altitude. The image also didn't break up as in this picture, but remained a single rectangle all the way.

[Soaring Feather]

I saw it while in Bon Aire, NV , Netherlands Antilles, beautiful sight.

[Dixie Mom]

I saw it in Negril, Jamaica once. (But I won't swear it wasn't the rum!) ;)

[Graewoulf]

We look, but do not see.
Then there is REALITY.

[da_toolman]

Has anyone else at FR seen the green flash?

I used to watch the Green Hornet, but I don't suppose that's the same thing.... 8^)

[Savage Beast]

I saw the flash several times from Esalen at Big Sur. The tubs are a good place to watch for it. They're a good place for most anything.

[phasma proeliator]

LMAO....

[Einigkeit_Recht_Freiheit]

There is no green flash.

There is no refraction. The earth is not round.


But, I must compliment you on your ability to manipulate a photo on a computer to make this picture appear realistic.

I am however, saddened by your insistence on perpetuating this "round earth" theory.