The Half-Astrophysicist Blog

A Convenient Ring Around the Moon…

Okay, I had my shot of the Moon and Mars all planned out, rising over the mountains.  It was going to be beautiful.  And then the clouds were there…

But sometimes the shot you get is not the one you expect.  I got a craving for a Sonic chocolate malt around 9:30 and when I stepped outside, there were high, thin clouds but the Moon and Mars were poking through.  Better yet, there was a ring around the Moon.  Ran back inside, got the camera and tripod, positioned a spooky tree in the shot and…

As usual, click to embiggen.  Mars is just to the left of the Moon.  To the right and above is Procyon.  Pollux is visible at the very top of the image (I cut off Castor).  The little greenish splotch right below the Moon is a lens flare caused by internal reflections and scattering in the lens system.  And of course there is the nice ring.

Rings such as this are formed by Moonlight interacting with ice crystals in the upper atmosphere.  These ice crystals are shaped like hexagons.

So, not quite what I was expecting, but a pleasant surprise tonight.


January 30, 2010 - Posted by | Astrophotography, Observing


  1. Just clicked from Phil Plaits Facebook posting! Glad I did, beautiful picture! Here near Vancouver, we have clouds. No Moon and no Mars, unfortunately! That’s ok, next year I hear it gets so close that it will look as big as a full moon! At least that’s what the email says! 😉

    Comment by apostaterebel | January 30, 2010 | Reply

  2. Thank you for the beautiful picture. It’s angelic. “I see the moon and the moon sees me.”

    Comment by Laci Olson | July 5, 2010 | Reply

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