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I must admit that even though I own property on the Moon I had never heard of the Purbach Cross, (sometimes called Werner X named after a nearby crater) until I read about it on page 45 of the April edition of Astronomy Magazine. I took one look at this strikingly elusive phenomena and said to myself, "I have got to get me one of those." Striking because it stands out from the rest of the Lunar landscape, like it doesn't belong, elusive because it only occurs during the Moon's 1st. quarter phase, (the first half Moon after the new Moon), and then only for a few hours, and on top of that, because the Moon's phases repeat every 29.53 days, you can't view this phenomena every month from the same location, you will be 12 hours early day 29, or 12 hours late day 30.
As I was reading this article I thought hey I've taken literally 100's of lunar images, maybe I've unwittingly, because that's how I usually do things, captured an image of the cross, after going through my collection of Lunar images, no luck. The article gave the exact date and time the cross would be available for viewing, April 12th. 8 pm EDT. So April 12th. comes around and I have clear skies, hopefully it will be our location's turn for the feature to show itself.
So I'm getting excited, go out to my POD, fire up the scope attach my Canon directly to said scope, point it at the Moon, push the shutter button, look at the camera's monitor, there it was,.................people, I had a moment, actually I'm having a moment right now thinking about the moment I had back then.
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The phenomena is created when Sunlight reflects off the higher crater walls of 3 back to back craters, Purbach, Blanchinus and LaCaille. If you would like your own personal X moment a list of the dates in Universal Time for the rest of the year when the Sun will be at the proper angle to create the X are below. You will need binoculars or a telescope to view the phenomena, look at the terminator just south of the Lunar equator.
May 12, 1530 UT; June 11, 0234 UT; July 10, 1255 UT; August 8, 2306 UT;
September 7, 0945 UT; October 6, 2126 UT; November 5, 1029 UT; December 5, 0050 UT.
Japan Aerospace Exploration Agency has released new Earthrise and Earthset videos taken by their Lunar satellite Kaguya, and they are nothing short of amazing. Also released are newly created topographic maps of the Moon, created with the data collected by the orbiter, 10 times more accurate then previous maps done of the Lunar surface, they also show locations of valuable minerals such as uranium, thorium and potassium. Below is a YouTube video of the New Earthrise/Earthset released by Jaxa.
