What are the Lunar X and Lunar V?
The Lunar X and Lunar V are transient optical features that appear only for a few hours around the first quarter moon and are visible through binoculars or a telescope.
These features are called the Lunar X and Lunar V because they resemble the letters ‘X’ and ‘V’ on the lunar surface.
How to see the Lunar X and Lunar V?
The Lunar X and Lunar V are visible along the terminator—the line that divides light and dark—of a first quarter moon.
The Lunar X becomes visible when sunlight reflects off the walls between the craters Blanchinus, La Caille, and Purbach on the lunar surface, while the crater floors remain in darkness.
Once you have seen the Lunar X, move your gaze further north (upwards) along the lunar terminator, and you will see the Lunar V.
The Lunar V becomes visible when sunlight reflects off the wall of the crater Ukert on the lunar surface, while the crater floor remains in darkness.
When to see the next Lunar X and Lunar V in 2026?
The next opportunity to see the Lunar X and Lunar V will be from 05:00 to 08:00 UTC on October 18, 2026, before the first quarter moon. The first quarter moon will occur on October 18, 2026, at 16:13 UTC.
Since the first quarter moon sets around midnight local time, this event will be favorable for observers in Hawaii and western North America.
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Ashim,
Thanks so much for publicizing this event. I just went out and checked today on the 5th to make sure the Moon was visible. Planning to set up the telescope in my driveway for some “sidewalk astronomy” and see if I can capture some interest on the street.
Hope for clear skies!
Jared
You’re welcome, Jared! Also don’t forget to observe the slim crescent Venus before it disappears from the evening sky in mid-March.
Could you please post the dates and times for the lunar X in 2026?
Hello Linda,
I have posted this for you. Please take a look.
Thank you so much, Ashim!