If you look up at the Moon on Thursday, March 6, you might catch a glimpse of something strange—two letters, “X” and “V,” temporarily appearing on the lunar surface.

No, the Moon isn’t sending us coded messages. This fascinating optical illusion is the result of sunlight casting shadows along the lunar terminator, the line that separates the Moon’s day side from its night side.

For a brief period, these shadows create an unmistakable X and V, which are visible through binoculars or a small telescope. Here’s how you can spot them and why they appear in the first place.

The secret behind the Moon’s “X” and “V”

Every celestial body illuminated by the Sun has a terminator, the dividing line between light and darkness. The Moon’s rugged surface, covered in craters, mountains, and valleys, interacts with sunlight in surprising ways.

Near the terminator, long shadows stretch across the lunar landscape, revealing fine details that are often invisible when the Sun is higher in the lunar sky. This effect makes the Moon look three-dimensional when viewed from Earth.

During the first quarter phase, a unique alignment of craters—specifically Purbach, La Caille, and Blanchinus—creates the illusion of the “X” shape. Meanwhile, another set of craters forms a “V” nearby. These letters are just our brains recognizing familiar patterns in random formations, much like seeing shapes in clouds.

When and where to look

On Thursday, March 6, the Werner X (named after the nearby Werner crater) will begin to take shape along the terminator at around 11 PM UTC. The illusion lasts for roughly an hour, so timing is key.

To find it:

• Use binoculars or a small telescope to scan the terminator line—the boundary between light and dark on the Moon.
• Instead of looking for specific craters, try spotting the bold “X” emerging from the shadows.
• The “V” should appear nearby under the same lighting conditions.

What if you miss it?

Don’t worry! The Moon’s phases repeat, and so do these fleeting shadows. If clouds or bad timing prevent you from seeing the lunar X and V this time, you’ll get another chance on April 5 and June 3.

These strange lunar illusions are a reminder of the Moon’s constantly changing appearance—and a great reason to grab a telescope and look up. Will you be watching?