Tomorrow, before dawn on Sunday, December 9, the moon meets up with Spica, the brightest star in the constellation Virgo the Maiden. Day after day, watch as the waning crescent moon slides along the line of stars and planets in the southeastern morning sky.
Get up before dawn right now to see the ecliptic – the pathway of the moon and planets – with the mind’s-eye. The planets Saturn, Venus and Mercury, plus the stars Spica and Zubenelgenubi, all help you to envision the ecliptic’s place on the great dome of sky.
Our chart at top shows the sky for roughly one and one-half hours before sunrise at mid-northern latitudes. The planet Mercury rises above the horizon (if it’s level) just as the predawn darkness gives way to dawn. If you have difficulty spotting Mercury, try drawing an imaginary line from Saturn through Venus to see this star-like light near the sunrise point on the horizon. Binoculars may be helpful.
As the Earth turns, the moon and Spica rise first in the wee hours tomorrow, followed by Saturn, then Zubenelgenubi, and then Venus. Mercury rises last, perhaps an hour or so after Venus does. If you’re not up until late dawn, you’ll probably only see the moon and Venus, the brightest and second-brightest orbs of nighttime.
Watch the moon for the next several days, as it parades down the celestial staircase in the morning sky. The moon couples up with Saturn on Monday, December 10, then with Venus on Tuesday, December 11 and finally with Mercury on Wednesday, December 12.
Thereafter, the moon will drop out of the sky, insuring us of dark nights for the upcoming Geminid meteor shower. What impeccable timing!
In the meantime, look for the moon to swing by Spica in the wee hours tomorrow, as the shrinking lunar crescent goes farther eastward (toward the sunrise) day by day.