Lunar X and Lunar V
Lunar X and Lunar V are famous transient, optical features on the lunar surface. They are visible only for a few hours around the first quarter moon through a pair of binoculars or a telescope.
These features are called Lunar X and Lunar V because they look like the letter “X” and the letter “V” on the lunar surface.
How to see Lunar X and Lunar V?
Lunar X and Lunar V are visible along the terminator of a first quarter moon. The terminator is an imaginary line that divides the light and dark sides of the moon.
Lunar X is visible when sunlight reflects from the walls between the craters Blanchinus, La Caille, and Purbach on the lunar surface, while the floors of the craters are still in darkness.
Once you have seen Lunar X, move your gaze further north (upwards) along the lunar terminator, you will see Lunar V.
Lunar V is visible when sunlight reflects from the wall of the crater Ukert on the lunar surface, while the floor of the crater is still in darkness.
When to see the next Lunar X and Lunar V in 2025?
The moment of first quarter moon will fall on June 3, 2025, at 03:41 UTC.
The next Lunar X and Lunar V will be visible from 13:00 UTC to 17:00 UTC on June 3, 2025 – a few hours after the first quarter moon.
Since the first quarter moon sets around midnight your local time, the above time is favorable for Asian observers.
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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.