Tonight – April 19, 2015 – you’ll want an unobstructed horizon in the direction of sunset, to maximize your chances of catching the young waxing crescent moon – and possibly the fading red planet Mars. The new moon was yesterday, April 18, so expect to see a whisker-thin lunar crescent low in the west after sunset – that is, if your evening twilight sky is clear. Binoculars may come in handy for the moon – and Mars. If you do see the ghostly smile of the whisker-thin crescent moon, it will be beautiful!
The sky chart above shows the sky scene for about one hour after sunset at mid-northern North American latitudes. At mid-northern latitudes in Europe and Asia, a thinner lunar crescent looms farther down from the red planet Mars, and sets sooner after the sun than it does in North America. At southerly latitudes in the Southern Hemisphere, the moon sets even sooner still, so you may not spot the lunar crescent until after sunset tomorrow, on April 20.
Look for the moon over the sunset point on the horizon as soon as dusk is giving way to darkness, because the moon will follow the sun below the horizon by nightfall or early evening at northerly latitudes, where people are more likely to spot tonight’s waxing crescent moon. You may miss out on Mars altogether, as this world struggles for visibility in the glare of evening twilight.
The red star Aldebaran and the Pleiades star cluster – sometimes called the Seven Sisters – reside above tonight’s moon. But you may well need to wait until after moonset to see Aldebaran or the Pleiades star cluster popping out into the darkening evening sky. From the Southern Hemisphere, the Pleiades cluster is more difficult to see, and may not be visible even with binoculars.
For northerly latitudes, April presents a good time for catching the mysterious zodiacal light after dusk (80 to 120 minutes after sunset). If you are blessed with a dark sky, look for the mysterious zodiacal light to jut upward from the western horizon, toward Venus, Aldebaran and the Pleiades cluster.
Time is quickly running out for viewing the two major signposts in the constellation Taurus the Bull: Aldebaran, the Bull’s eye, and the Pleiades cluster. That’s because the stars of the Bull set some four minutes earlier with each passing day, so Taurus’ stars are quickly sinking into the glare of sunset.
Annually, the sun passes in front of the constellation Taurus the Bull from about May 14 to June 20. The sun has its yearly conjunction with the Pleiades cluster around mid-May and its conjunction with the star Aldebaran at or near June 1.
Bottom line: Find an unobstructed horizon in the direction of sunset. If blessed with clear sky, you just might catch the young moon, the planet Venus, the star Aldebaran and the Pleiades star cluster.