Find the Elusive Lunar X

Several times a year at the moon’s first quarter phase, a feature called the Lunar X becomes visible in strong binoculars and small telescopes. For a few hours centered on approximately 11 p.m. EDT on Saturday, October 5, the illuminated rims of the craters Purbach, la Caille, and Blanchinus will form a small, but very obvious X-shape. Using binoculars or a backyard telescope, look for the X along the terminator, and about one third of the way up from the southern pole of the moon

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