An 18-hour-old crescent moon photographed with a 12-inch telescope on April 22, 2012. An even younger moon may be visible tonight in the southwestern sky shortly after sundown. Credit: John Chumack and Maurice Massey
2014 begins with a chance to spy an exceptionally thin crescent moon shortly after sunset and possibly the shimmer of aurora at nightfall.
The thin crescent about 1.5 days before new moon on Jan. 21, 2012. Credit: Bob King
The moon’s age is determined by how many hours or days have passed since new moon phase. New moon occurs once a month when the moon lies in nearly the same direction as the sun in the sky. No one can see a new moon because it stays very close to the sun and hides in the glare of daylight.
Under favorable circumstances it’s not too difficult to spot a 1-day-old moon, referred to as a young moon because it’s the first or youngest bit of moon we see after new moon. Young moons are delicate, faint and tucked far down in the twilight glow shortly after sunset.
Spotting a moon fewer than 24 hours old requires planning. You need a flat horizon, haze-free skies and a pair of binoculars. Being on time’s important, too. Be sure to arrive at your observing spot shortly before sundown. Knowing the point on the horizon where the sun sets will guide you to the crescent’s location.
Venus – still visible low in the southwestern sky at dusk – will also be a big help tonight. It’s perfect for getting a sharp focus with your binoculars, essential for seeing the faint lunar crescent clearly. The planet hovers some 7-8 degrees to the moon’s upper left. When you focus on it, you’ll be in for a surprise. I wish I could tell you, but that would spoil the fun.
Diagram showing the sky facing southwest from the Minneapolis area 20 minutes after sunset or at 5:02 p.m. today. The moon will be about 3.5 degrees high at the time. The view will be similar across the Midwest. Further west, the moon will be somewhat higher and closer to Venus. Stellarium
New moon occurred at 5:14 a.m. (CST) today, making tonight’s crescent approximately 12 hours old for skywatchers in the Midwest. Since the moon’s orbit carries it moves east of the sun its own diameter every hour, skywatchers in the western U.S. will have a somewhat easier time of seeing it. From Denver, the moon will be 13 hours old, San Francisco 14 hours and Hawaii 16 hours.
Given that the record for the earliest naked eye sighting of the moon after (or before) new phase is 15 hours 32 minutes and the earliest binocular/telescope observation is 11 hours 40 minutes, most of us will need some kind of optical aid to spy tonight’s silvery sliver.
I recommend a pair of binoculars in the 35mm-50mm range with a generous field of view. Oh, and don’t forget your heavy coat and boots for warmth. Locales with open horizons are generally the windiest places in the world.
Now here’s a lovely view. The waning crescent moon rises above Earth’s atmosphere as seen from the International Space Station. Credit: NASA
Here’s a checklist of what you’ll need:
* Figure out your sunset and moonset times HERE. That way you’ll know exactly when and for how long to watch.
* Thank your lucky stars if the sky is extremely clear and without haze or clouds in the southwest direction.
* Arrive no later than sunset, face toward the direction of sunset and focus your binoculars or telescope on Venus, that brilliant “star” you’ll see about 1 to 2 fists high in the southwestern sky.
* Start looking for the moon 10 minutes after sunset by slowly sweeping the sky just a few degrees above the sunset point. Continue to look for the next 25 minutes giving your eyes an occasional rest and checking focus. You’ll be looking for the thinnest of the thin, no more than a partial arc scratched across the deepening blue.
* If you spy the moon in binoculars, carefully lower them and try to find the moon with your naked eye.
Whether you have success of not, I welcome anyone who attempts this observing challenge to share your observation in our comments section. Good luck to you!
The coronal hole – photographed on Dec. 30 in far ultraviolet light – that might could lead to a chance at seeing the northern lights tonight and tomorrow nights. Credit: NASA
Later this evening and tomorrow as well, there’s a chance that a high-speed stream of particles cut loose from a coronal hole – a open magnetic portal in the sun’s corona that allows electrons and protons to flow freely into space – could kick-start minor auroras at high latitudes. Sometimes that means folks living in southern Canada and along the U.S. northern border can see them too.
You’ll find no lack of sunspot groups on the sun today. This photo was taken by NASA’s Solar Dynamics Observatory this afternoon at 12:15 p.m. CST. Moderate solar flares are possible from Region 1944 (just entering the disk) and departing 1936. Credit: NASA
The sun has recently been more active with an M-class flare yesterday from the 1936 group and the potential for more. Be on the lookout this evening and next for a small display. With little to no moon in the sky, these are good times to look for auroras.