Wednesday, February 18, 2009

Kaguya captures Earth diamond ring effect

On February 9 the lunar orbiter Kaguya successfully imaged the moment when Earth and Sun created the "familiar" (on Earth) diamond ring effect, usually reserved for that moment when, during a full eclipse by the Moon of the Sun, the Sun's photosphere bursts through valleys between mountains on the limb of the Moon. This time, Earth and Moon switch places, and Kaguya captured the sun not fully eclipsed by Earth, using its onboard HDTV camera.

"The moment came when a penumbral lunar eclipse occurred and the view of the Sun from the Kaguya was mostly covered by the Earth," today's JAXA news release reports, "thus the earth looked like a diamond ring.

"This is the first time this phenomenon was shot from the Moon."

1 comment:

Joel Raupe said...

Having watched the movie of this event, from which the still image of the "Diamond Ring Effect" was lifted, the aphorism that "text without context is error" came to mind as being well-illustrated.

I don't want to dispute either the First of a Kind claim by JAXA or the diminish the accomplishments made by Japan in performing this exceptional mission, but I am no longer sure this qualifies as a true comparison with the Diamond Ring Effect as seen from Earth.

First, the from a movie from which the still was taken clearly took place during an Earthrise, beginning with the full ring of atmospheric refraction coming into view at the top. Then the not-fully-eclipsed Sun's photosphere bursts into view, and the still is only of the instant between being obscured and when the sun's surface bursts fully into view. It is not a Baileys Bead but an instant of phase between a camera's obscured view of a partial eclipse and its full view of a partial eclipse.

It's phenomenal, certainly, but to compare it with the Diamond Ring Effect may be to diminish the remarkable geometry of a true Diamond Ring effect as seen during a total eclipse of the Sun by the Moon, at nearly the precise same apparent size as seen from Earth.

Am I a party pooper?