Tonight, the crescent moon will look about a wide as an unclipped fingernail. You’ll spot it right away in the southwestern sky at dusk, high and bright. Just 2° (four moon diameters) to the moon’s upper right lurks another member of the solar system, the planet Neptune. The two are in conjunction tonight in the dim constellation Aquarius.
Small telescope owners can use the lunar crescent to find their way to the planet, which looks like a blue-hued star at low magnification. But if you up the power 150x or higher, Neptune will show a small disk compared to the pinpoint stars. It’s always nice to have the moon around to help us find the dimmer planets. A 3-inch telescope will show Neptune easily.
Want to test your observing skills? Try finding it in binoculars. 7×50, 10×50 or 8×40 glasses will typically show the planet from outer suburban areas. With the moon nearby tonight, the extra light will make spotting the planet a little more challenging. Mounting the binoculars on a tripod can really help in seeing fainter stuff, but if you can’t do that, brace yourself against a door or wall and hold them as steady as you can. Focus on the stars and avoid looking directly at the moon to preserve your night vision.
Did I just say avoid the moon? Please don’t do that. After you’ve attempted Neptune turn back to the moon. Most binoculars will show a line of craters along the inner curve of the crescent, the line separating the sunlit part of the moon from the part that’s still in darkness called the terminator.