If you live in Northern Hemisphere – North America, Europe or Asia – you might be able to catch an exceedingly young lunar crescent below the planet Jupiter after sunset on April 11, 2013. Look for Jupiter to pop out pretty much due west fairly soon after sundown. It’ll be the first star-like object to appear as night falls. As soon as you see Jupiter, look below it for the whisker-thin crescent moon near the horizon. From mid-northern latitudes, you’ll be looking to Jupiter’s lower right. At northern tropical latitudes, look more directly below Jupiter. All other things being equal, it’ll be hardest to spot the young moon in Asia and easiest to spot in North America. From the Southern Hemisphere … well, your chances are not as good for seeing the April 11 moon; reasons explained below.
As always, binoculars enhance any search for a young moon.
After the sun goes down, look for the moon and Jupiter to be somewhat more 30o apart. For reference, a fist held at an arm length covers about 10o of sky. Remember to seek the moon as soon as darkness falls. The thin crescent will follow the sun beneath the horizon by the time that it gets good and dark.
Springtime is the best time to catch a young crescent, because that’s when the waxing crescent moon stands most directly above the setting sun. In springtime, evening crescents stay out longer after sunset than at other times of the year. It’s spring now in Earth’s Northern Hemisphere, so northerly latitudes are favored for seeing the young moon on April 11. Meanwhile, it’s autumn in the Southern Hemisphere, and the crescent will be located to the right side of the sunset. It’ll be lower in the sky, set sooner after the sun and generally be harder to spot.
As the razor-thin lunar crescent makes its appearance after sunset today, keep in mind that you’re looking at the moon on the day after new moon. The new moon fell yesterday, on April 10, at 9:35 Universal Time (5:35 a.m. Eastern Daylight Time, 4:35 a.m. Central Daylight Time, 3:35 a.m. Mountain Daylight Time, 2:35 a.m. Pacific Daylight Time). So it’s a very fragile and thin moon you’ll see in the west after sunset – if your sky is very clear and you are able to spot it.
In your search for the newborn crescent, find an unobstructed western horizon – and if possible, a hilltop – and have binoculars handy. At mid-northern latitudes in the U.S., the moon sets about one and one-half hours after sunset. At mid-northern latitudes in Europe, it’s more like one and one-quarter hours after sunset, and in western Asia, about one hour after the sun.
Bottom line: Starting 30 to 45 minutes after sunset today, look below Jupiter and above the sunset point on the horizon with binoculars. You just might spot the pale, whisker-thin crescent moon smiling at you at dusk. It will be low in the western twilight sky. If you miss the moon this evening, try catching an older but a more photogenic young moon basking in earthshine on Friday, April 12.