If you get up no more than 30 minutes before sunrise on Tuesday, December 11, you still might be able to catch the waning crescent moon pairing up with the dazzling planet Venus in the glare of morning dawn. After all, the moon and Venus rank as the second-brightest and third-brightest celestial bodies, after the sun. But to see tomorrow’s early morning scene best – with the planet Saturn above the moon and Venus, and the planet Mercury below – you need to get up around 60 to 90 minutes before the sun. Saturn and Mercury shine nowhere as brilliantly as the moon and Venus, but they are as bright as the brightest stars. It’ll be beautiful.
Draw an imaginary line from Saturn through Venus to locate Mercury near the horizon just as darkness gives way to dawn (90 to 60 minutes before sunrise). Mercury will be low in the sky, so you’ll want a clear and unobstructed horizon in the direction of sunrise. If you have binoculars, bring them along. Binoculars help you to spot Mercury whenever a murky sky obstructs the view.
Binoculars also highlight the soft glow of earthshine on the dark side of the moon, though you can see earthshine with the unaided eye as well. For North American residents, tomorrow morning may well be the last chance to see the waning crescent moon and earthshine in the December 2012 morning sky. But for people in the world’s Eastern Hemisphere – eastern Asia, Indonesia, Australia and New Zealand – there’ll be a close conjunction of the waning crescent moon with Mercury at early dawn on Wednesday, December 12.
Meanwhile, look for the two brightest orbs of nighttime – the moon and Venus – to pair up in the predawn and dawn sky on Tuesday, December 11.