I feel like the chamber of commerce for the current apparition of Venus and Mercury. I can’t help it. Usually, you’ll see one or the other at dusk or dawn, but the two have been paired up low in the western sky for more than week. For anyone who’s never seen Mercury, this will be the best and easiest time all year to do so. As if two planets weren’t enough, the wiry moon will join the scene Sunday evening (March 18).
You can start watching for all three between about 40 minutes to 1 hour 15 minutes after sunset. Find a spot with a view low down to the western horizon and look about one outstretched fist above it. Venus and the moon should be obvious. Once they’re in view you can track down Mercury to the upper right of Venus.
Got a camera? If it has image stabilization you can take a hand-held photo of the scene. If not, attach it to a tripod and experiment with different exposures at ISO 400. Open the aperture of your lens to f/4 and start with 1/60 of second, then increase to 1/30th, 1/15th, 1/8th and 1/4 second. One of those should be the lucky ticket. If the images are too dark, up your ISO to 800 and try again. Check the camera’s back viewing screen to see which exposure gives the best picture.
Most cameras use autofocus, so be sure to set your focus spot on the moon or Venus before taking pictures. They’re bright enough to activate the sensor. If autofocus still wanders, focus on Venus or the moon and then slide the switch on the side of your lens from “A” (auto) to “M” (manual) and leave it there. Now, all your conjunction photos will be shot in focus at infinity. Just remember when you’re finished to slide the button back to A, so you’re ready set again for daytime photography.
This should be a very nice event to see. Clear skies!