Tonight is the last night to see Jupiter, Venus and Mercury all within 5 degrees of each other in what is called a planetary trio. You can find them in the west just as the sun sets. This is the closest grouping of three planets you'll see until January 2021.
Last night Jupiter and Venus were at their closest (1 degree apart) as Venus passed Jupiter in right ascension. We finally had relatively clear skies (the marine layer can be brutal here this time of year). I missed the closest grouping of the three on the 26th (when they were all within 3 degrees of each other) because of clouds and fog and I didn't plan on shooting last night...so I had no pretty foreground because I was shooting over the fence in my backyard! Tonight the three will form a relatively straight line as they stack on top of each other, so if the sky is clear I hope to be someplace a bit more scenic.
A friend asked how I know ahead of time to watch for things like comets, planetary alignments and eclipses and I had a one word answer...RESEARCH. Outdoor photographers typically spend more time researching and planning than they do actually shooting. If you like to shoot night skies you really need to know what's going on up there! In addition to the cool things like alignments and eclipses every outdoor photographer absolutely must know the moon phase and location to plan a night shoot.
Two of my favorite resources to stay on top of what's going on in the night skies are:
Sky and Telescope's This Week's Sky at a Glance
For night shoot planning my favorite tool is The Photographer's Ephemeris. This map-centric tool will help you see the exact direction of sun/moon rise/set and how the light will fall for any location in the world. The best part is that you can account for things such as the height of surrounding mountains so you can know exactly when you will lose daylight or see the moon pop over the top of the mountain. The desktop version is Free and there are versions for iOS and Android phones.
Do you have any other favorite sites or tools for keeping track of the night sky?