See the Lunar X and V (peaks at 9 p.m. EDT)

Several times a year near the moon’s first quarter phase, small clair-obscur effect features on the moon called the Lunar X and the Lunar V become visible in strong binoculars and backyard telescopes for a few hours. The Lunar X, a prominent X-shaped pattern, appears when the rims of the craters Purbach, la Caille, and Blanchinus are illuminated from a particular angle of sunlight (inset). Look for it beside the terminator about one third of the way up from the southern pole of the Moon. The Lunar V forms along the northern span of the terminator near the crater Ukert. On Wednesday, July 2 the features are predicted to start developing by about 9 p.m. EDT (or 01:00 GMT on Thursday, July 3), peak in intensity at around 10:15 p.m. EDT (or 02:15 GMT on July 3), and then gradually fade out toward midnight Eastern time. The event will occur during waning daylight for observers in western North America – but you can observe the moon in a telescope during the daytime, as long as you take care to avoid aiming it near the sun. The Lunar X will be visible anywhere on Earth where the moon is shining, especially in a dark sky, between 01:00 and 04:00 GMT on July 3.