We had just enough breaks in the clouds to enjoy the Mars-moon conjunction last night. I loved seeing the color contrast between the two celestial bodies, something you can really only appreciate when they’re close together. The moon will be near the Red Planet again tonight but about a fist fist to its left or east.
Did you know that the moon will be in conjunction with another planet tonight? It passes just 3.5° below distant Uranus, which is 1.8 billion miles (2.9 billion km) or 38 times farther from the Earth than Mars. I’m certain that a small telescope will show the 7th planet with ease even with the bright moon nearby, but I wonder if we might also see it in binoculars. In a moonless sky, Uranus is easy prey for a 7×35 or 10×50 glass, but lunar glare makes tonight’s conjunction an excellent observing challenge. Want to give it a try? Use the chart to track down Uranus, located to the north of the moon in the same binocular field of view.
Like some of you I like to photograph conjunctions of the moon and planets, but as you’ve probably discovered already, it’s not always easy. The biggest problem is the difference in brightness between the moon and the planet. Twilight tempers the overbright moon and makes it easier to get a photo showing both objects. But if they’re only visible in a dark sky — as the moon and Mars were last night — it’s impossible to make Mars appear bright the way it does to your eye without overexposing the moon. This is especially true when the moon’s phase is half or more.
One way to tone down the moon is to photograph it near the horizon where the denser air acts as a filter. I tried that with modest success. Or you can expose the moon properly and accept the fact that Mars will appear very tiny and not particularly bright as depicted in the photo above. But if I’m lucky and clouds are about I make them my friends. No surprise, clouds heavily filter moonlight. If you carefully monitor their progress across the moon’s face you can catch moments when the moon is mostly covered or faintly visible through them while the planet (Mars) pops into bright view in gaps between the clouds.
As you watch the movement of the clouds you can anticipate when a planet-gap coincides with a masked moon and take photos like crazy to seize the moment. Of course we don’t always have clouds to lend a hand. That’s where Photoshop and other digital imaging tools are useful. I use them to even-out differences in the brightness values of the moon, clouds, planets and horizon as best I can. My goal is always the same — to make the final image look as close as possible to the way it appeared to the eye.