Nearly a decade ago, my excitement surged as I captured my first telescope photo of the Moon. With a makeshift setup, I clumsily held my phone camera up to the eyepiece. After a few shaky attempts, I got a clear snapshot of the lunar surface, and shared it online with pride.

Unbeknownst to me, I had clicked the picture during a brief 4-6 hour window each month when fascinating features known as Moon’s X and V could be visible.

These lunar marks are optical illusions, revealing themselves only when sunlight strikes the rims of specific craters during the Moon’s waxing phase, perfectly aligned along the terminator.

The Moon’s X forms a bright X shape, illuminated by sunlight on the edges of three craters: La Caillou, Blanquinus, and Pulbach. Similarly, the V shape comes to life as sunlight hits the Ukert crater and nearby smaller craters.

To witness the Moon’s X and V, a telescope is essential. However, timing is crucial. The visibility of these features varies globally and is influenced by your local time zone.

The next waxing moon occurs at 5 AM GMT on January 26th. However, residents in the UK may miss it as the Moon will be below the horizon then. The best viewing opportunity on the evening of January 25th will be in New York, where the first quarter appears around midnight, enabling visibility of X and V from about 10 PM to 2 AM. In places like Sydney, the daytime blocks visibility as the first quarter falls around 3 PM local time.

For the best chance to view the Moon’s captivating X’s and V’s, ensure you’re gazing at a waxing moon during optimal hours, preferably when it’s high in the night sky. Tools like Stellarium can help you track the Moon’s visibility on specific dates.

Mark your calendars for upcoming first quarter events on February 24th, March 25th, and April 24th-25th. If you’re in the UK, you might want to target March 25th as it aligns well with evening visibility around 7 PM local time.

Understanding the intricacies that must align for the Moon’s X and V to appear, I feel fortunate to have captured my first lunar photo during such a special moment.

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Abigail Beer is the feature editor of New Scientist and author of The Art of Urban Astronomy. Follow me on Twitter @abbybeall