This Week's Sky at a Glance, February 19 – 27


■ First-quarter Moon (exactly so at 1:47 p.m. EST). The Moon shines between Aldebaran and the Pleiades high this evening, as shown below. Every February, the first-quarter Moon is in their vicinity.

The Moon, waxing through first quarter, passes the similar-looking duo of Mars and Aldebaran high in the evening. But of course they’re not similar at all. Mars is a cold, dusty, rusty ball of rock currently 10 light-minutes away. Aldebaran is a dazzling fireball 9,000 times larger in diameter than Mars and 67 light-years away. If Mars were a 1-millimeter mustard seed 100 feet from