On the evening of February 6, 2014, the moon will be in front of the constellation Aries the Ram. It’ll be at or near its first quarter phase, when the lunar disk appears from Earth to be half-lit in sunshine and half-engulfed in the moon’s own shadow. The moon is now waxing (increasing in phase) and will turn full on February 14. The moon on the night of February 6 shines in front of the zodiacal constellation Aries the Ram, but is heading for the zodiacal constellation Taurus the Bull.
Despite the lunar glare, you might be able to detect the constellation Taurus’ two major signposts to the east of tonight’s moon. These stellar gems are ruddy Aldebaran, the constellation’s brightest star, and the beautiful Pleiades star cluster, a tiny dipper-shaped conglomeration of starlets all wrapped up in mist. For a real treat, look at the Pleiades through binoculars sometime!
The moon and stars will appear to go westward throughout the night tonight, as they do every night. But this motion is actually an illusion, created by Nature’s sleight of hand. The Earth spins on its rotational axis from west-to-east, making it appear as if the sun, moon and stars move westward while the Earth stands still. In fact, as you know, Earth is spinning beneath the sky. And, if you closely watch the moon, you can detect its true orbital motion by noticing its distance to various bright stars from night to night. The dark side of a waxing moon always points eastward, or in the moon’s direction of travel in front of the backdrop stars.
Tomorrow evening, on February 7, you’ll see that the moon has moved closer to the star Aldebaran and the Pleiades cluster. The moon’s change of position relative to the background stars reveals how far the moon has traveled in its orbit around our planet Earth, as seen on our sky’s dome.
Bottom line: This evening – February 6, 2014 – the moon shines in front of the constellation Aries the Ram. It will be in front of Taurus the Bull on the evening of February 7. If you notice stars near the moon tonight and tomorrow night, you can get a sense of the moon’s true motion in orbit around Earth.