Observing the Lunar X & V on October 28, 2025

December 2025  :  Greg Shanos

One of my favorite “features” on the moon is the Lunar X & V. This phenomenon is predictable and occurs on a monthly basis. (See table 1).  

The Lunar X (also known as the Werner X) is a claire-obscure effect in which light and shadow create the appearance of a letter 'X' on the rim of the craters Blanchinus, La Caille and Purbach. The X is visible beside the terminator about one-third of the way up from the southern pole of the moon. The Lunar V forms along the northern part of the terminator near the crater Ukert. (See images 1-2)  

I advise all amateur astronomers to consult this table to see if the Lunar X & V will be visible from your location. Time and date are listed in Universal Time therefore each individual observer will need to convert to their local time in order to observe the event. The easiest way to do this is with a free program called WinJupos. (https://jupos.org/gh/download.htm) WinJupos states both Universal Time and Local Time for the Sun, Moon and Planets. Enter your latitude and longitude first, then enter Universal Time stated on the table and your local time will appear above. Since the Moon was riding low in the sky at approximately 37 degrees above the horizon, I began my imaging session soon after sunset in the daylight.   

Fortunately, the X &V can appear sooner and last several hours later than the stated time on the table. This is a good thing, since it may be cloudy at the start of the event and an hour later the clouds may have dissipated. The Lunar X & V will still be visible!  

In conclusion, the Lunar X & V is a monthly phenomenon not to be missed. Check the table, convert Universal Time to Local Time and see if it will be visible from your location. If it is, then get out your telescopes and cameras and submit your observations to ALPO’s the Lunar Observer care of David Teske. david.teske@alpo-astronomy.org    

Image 1: The Lunar X & V stands out in high relief on the disk of the moon on October 28, 2025 at 7:11pm local time or 23 11m UT. The moon was at 43% phase and only 37 degrees above the horizon. Weather conditions were ideal with perfectly clear skies and good seeing conditions. The image was taken in daylight with sunset at 6:52pm local time. An Orion ED80T CF 480mm fl f/6 triplet apo carbon fiber refractor was tracking on an Orion EQ-2 mount. A ZWO ASI 178MM monochrome camera and Baader CMOS optimized UV-IR cut filter using Firecapture v2.7.15 acquired the video through the refractor. Computer utilized was an MSI GF65 gaming computer upgraded to 40GB of RAM. The SER video was processed using Autostakkert 4.0.13 and Registax 6.1.0.8. Further sharpening and processing in Photoshop CS4. Image by Gregory T. Shanos Longboat Key, (Sarasota), Florida.

Image 2: The Lunar X & V stand out in high relief on the disk of the moon on October 28, 2025 at 7:24pm local time or 23h 24m UT. The moon was at 43% phase and only 37 degrees above the horizon. Weather conditions included clear skies with good steady seeing. Image was taken with an altazimuth driven Meade LX200GPS ACF 8-inch GO-TO Schmidt-Cassegrain telescope utilizing an Optec 0.62X focal reducer. A ZWO ASI 178MM monochrome camera with an Optolong UV-IR cut filter using Firecapture v2.7.14 to acquire the video. Computer utilized was an MSI GF65 gaming computer upgraded to 40GB of RAM. The SER video was processed using Autostakkert 4.0.13 and Registax 6.1. Further sharpening and processing in Photoshop CS4. Image by Gregory T. Shanos Longboat Key, (Sarasota), Florida.

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