Bad Astronomy

If You Wanna See Venus, Better Hurry!

Venus
That’s no moon.

Photo by Phil Plait

If you’ve been outside after sunset and looked to the southwest, you can’t have missed the astonishingly bright beacon glowing over the horizon. That’s Venus, the third brightest natural object in the sky (the International Space Station can sometimes briefly outshine it).

Venus orbits closer to the Sun than Earth does and moves faster in its orbit. It’s “catching up” to Earth right now, like a car on an inside circular track passing a car outside it. From our view, we see Venus growing larger as it gets physically closer to us, as it simultaneously appears to get closer to the Sun in the sky every day. That means if you go out every night at the same time—say, 20 minutes after sunset—Venus will be lower every evening. By early January it’ll be too low to the horizon at sunset to spot, so go and see it while you can!

The geometry also means Venus is a very thin crescent right now, like a new Moon. As it happens, for Christmas I got what’s called a T-adapter and ring, which allow me to hook up my camera to my telescope. As soon as the Sun set on Christmas day, I was outside freezing my asteroid off to get pictures, like the one above. I also took a short video and gave a running commentary as it recorded (make it full screen to see it best):

It was fun to watch Venus slowly move across the field as the moving air above the Rocky Mountains caused the crescent to bubble and boil. I was amazed to see the planet as an obvious crescent in my small (10x50) binoculars; if you have a pair, I strongly urge you to take a look! But seriously, hurry: Venus is screaming down in the west right now and will only be easily visible for a few more days. After that, you’ll have to wait until the end of January for it to be easily visible in the east before sunrise.

And since it’s a FAQ whenever I tweet about using my observing equipment: I have a Celestron 8” SGC (XLT) telescope, a Canon T4i camera, and the adapter (and ring) to mount it is available at Celestron or through various other companies. They make adapters for every major camera brand, so it’s not too hard to find what you need.

I am very much looking forward to playing with this setup more. Jupiter is up not very long after sunset, for example, and makes a fantastic target. If and when I get good shots, trust me, I’ll post ‘em here!