May is Moon Month with three significant events occurring, namely two Micromoons and a Lunar X & V. There were two full Micromoons with the first occurring on May 1st, 2026, and the second on May 31st, 2026. Sandwiched between these two events was a Lunar X & V on May 23rd, 2026.
Full Moons are given nicknames that match natural occurrences for that particular month such as February’s Snow Moon, June’s Strawberry Moon and December’s Cold Moon. The Moon phases take 29.5 days to complete, which means it takes just 354 days to complete 12 lunar cycles. This is 11 days short of a year with 365.25 days. Therefore every 2 to 3 years a 13th full Moon referred to as Blue Moon is observed within a calendar year.
There are two types of Blue Moons, neither of which have anything to do with color. A seasonal Blue Moon is the traditional astronomical definition, and refers to the third full Moon in a season that has four full moons. The second definition, which arose from a misunderstanding of the original, is the monthly Blue Moon, referring to the second full Moon in a single calendar month. In 1946 Sky & Telescope magazine mistakenly defined it as the second full Moon in a calendar month. Today, the monthly Blue Moon is accepted as the popular definition as opposed to the astronomical seasonal definition.
The true astronomical Blue Moon relates to an astronomical season. An astronomical season is the period of time between an equinox and a solstice, from spring equinox to summer solstice and autumn equinox and winter solstice. Within that time, we usually see three full Moons. A seasonal Blue Moon is the third full Moon in a quarterly season of four full Moons vs. the usual three. The astronomical seasonal Blue Moon is a more difficult idea in comparison to a monthly blue Moon. A seasonal Blue Moon is also slightly rarer than a monthly Blue Moon, as a monthly Blue Moon has a higher statistical chance of occurring.
Since the Moon’s orbit is elliptical there are times when it’s very close to Earth, and times when it’s much farther away. At its closest approach, known as perigee, it is called a Supermoon. At its farthest distance known as apogee from Earth, it is called a Micromoon. The Moon on May 1st and May 31st were both Micromoons. A Micromoon typically appears about 12% to 14% smaller than a Supermoon. This slight decrease in size is imperceivable to the naked eye. See Images 1 & 4.
On May 23, 2026, the Lunar X & V were also visible. The Lunar X (also known as the Werner X) is a claire-obscure effect in which light and shadow creates 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.
Each monthly issue of the Lunar Observer publishes a table stating the time the Lunar X & V will be visible. For the month of May it will occur on May 23, 2026 at 22h 45m UT which is 6:45pm local time with the Sun still 18 degrees above the horizon from my location. The weather was clear with light clouds, haze and humidity. I successfully imaged the X & V at this time and noted that only the V was visible with the X not yet fully formed. It took several hours for the X to become visible. This makes the observation even more interesting since you can watch the X appear in real time! See Images 2 & 3. Fortunately, the X &V will appear and last several hours later than the stated time on the table published in the Lunar Observer. 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 my case the opposite occurred with the weather taking a turn for the worse with completely overcast skies at 9:30pm. I was therefore successfully able to take many images within this 3.25-hour period. Unfortunately, from my location the next Lunar X & V will not be visible until January 15, 2027 at 00h 15m UT or January 14, 2027 at 7:15pm local time. I have to wait six months for the next X & V, which is well worth the wait!
On May 30, 2026, the second Micromoon or Blue Moon was visible. See Image 4. The weather was completely overcast for the entire day. In Florida, if you do not like the weather just wait a minute and it will change. Fortunately, as the evening hours progressed the clouds were breaking up with moving cloud banks that became thinner and thicker as the evening progressed. I was able to successfully image the Micromoon through the thinner clouds. There was also much haze and humidity. The seeing was rather good and steady.
Overall, the lunar triple header was a complete success. I was successfully able to witness and image all three events! There is always something interesting happening with the Moon that warrants observation and imaging. Recommend subscribing to the references since most send a daily or weekly newsletter to your email regarding interesting phenomenon that occur in sky that are of interest to amateur astronomers.
