Lunar X Sidewalk Astronomy

This evening, I knew that my home astronomy club, the San Antonio Astronomical Association, was going to set up scopes at a bookstore to see the Lunar X. Just for something different, I decided to set my scope up on my driveway and see if I could attract some of my neighbors to see this sight.

The Lunar X is a pattern formed on the moon near the first quarter when sunlight just touches the top of several craters at the terminator. It is fun to find, because it is visible in the evening for only a few hours every other month.

In the image to the left, south is up and west is left. The lunar X is near the bottom of the photo and the V is near the top.

On this night, I knew that the right time to observe was from 515 PM to 830 PM local time in San Antonio. The sun did not set until the end of the window that was open for observation, so the operation in my front yard was more shade tree astronomy than a star party.

I was able to persuade 18 folks to come over and take a look through my scope in the three hours I was set up. I met several neighbors I had never had the opportunity of meeting. So the sidewalk astronomy was good for neighborhood friendliness too.

(As an aside, other members of the club, set up at the bookstore had over 300 visitors! They worked hard in the 104 degree heat. I napped and had relaxing conversations with my neighbors as they occasionally came by. Each place had its pluses and minuses.)

To prepare for the evening, I set up a table with a large scale map of the lunar surface and printed a photograph of the Lunar X. I used my 10mm Radian eyepiece for a 120X view of the moon.

I quickly discovered that the easy way to get people to look at the right place was to describe three nearby craters as "the two eyes and the open round mouth below them". Once the visitor had that in sight, looking just right of the rightmost eye located the X. As time went on, I also could see the Lunar V just above the X in my dobsonian scope.

As an experiment, I took several photographs through the eyepiece with my little Stylus camera. After cropping the picture, I have posted that cropped version with this entry. It is pleasantly blue colored, just like the image appeared in the late afternoon blue sky. I tweaked the contrast about 10 percent before uploading.

I also logged my sidewalk adventure in the night sky network to give my home club credit for the visitors I reached. Big Fun. Several of the neighbors told me to give them a call the next time I was out looking at objects in the sky. I think I will.