This evening – February 7, 2014 – the waxing gibbous moon shines in front of the constellation Taurus the Bull. Despite the moon’s glare, you should be able to make out the Bull’s brightest star, Aldebaran, and the Pleiades star cluster, aka the Seven Sisters. Meanwhile, the brightest starlike object near the moon – brightest “star” in the sky most of the night – isn’t a star. It’s the planet Jupiter.
Although the moon and Jupiter (and all the stars) go westward during the night, the moon is actually going eastward relative to the backdrop stars (and Jupiter, too). The moon, planets and stars appear to go westward for the same reason that the sun appears to go westward during the day. The Earth spins from west to east on its rotational axis, making it appear as if these celestial bodies are traveling from east to west across the sky every day while the Earth stands still. But it’s really the Earth that’s doing the moving.
The dark side of a waxing moon always points eastward, or in the direction of the moon’s orbital motion. Take a close look at tonight’s moon and you might be able to discern that Jupiter lies to the east of the moon on the sky’s dome. Over the next several days, watch for the moon to edge closer and closer to Jupiter.
Later this month, after the moon drops out of the evening sky, use the planet Jupiter and the constellation Taurus to imagine the ecliptic – the pathway of the planets – with the mind’s-eye. The ecliptic runs past Jupiter and in between the star Aldebaran and the Pleiades star cluster.
The ecliptic is an imaginary semi-circle on the great dome of sky, arcing all the way from the eastern horizon to the western horizon. The constellations of the Zodiac run astride the ecliptic, defining the narrow beltway of the stars through which the sun, moon and planets forever travel.
Bottom line: On the evening of February 7, 2014, the brightest starlike object in the sky is Jupiter. The moon shines in front of the constellation Taurus, in the vicinity of the star Aldebaran and the Pleiades star cluster. The moon never really stays still relative to the stars of the Zodiac, though, going its own diameter eastward every hour.