January SkyTalk | Binocular Spectacular – Part I

A fascinating celestial event sure to thrill sky-watchers will happen on the early evening of January 10th when the two innermost planets of our Solar System will have an apparent “near miss” in the sky! And while this can be witnessed with the unaided eye, it will be a superb sight in binoculars of all sizes and types. So dust off those glasses should you have a pair and hope for a clear night.

It’s natural to think of telescopes when mentioning “stargazing” but for many special events binoculars with their low powers and wide fields of view are actually preferred. One such is the close approach of two or more celestial objects in the sky. Known as “conjunctions,” they are typically best-seen in such glasses. And the next two months offer a wonderful opportunity to experience this for yourself. Looking low in the west-southwest about 45 minutes after sunset on the 10th of January, you will see brilliant Venus and just to its lower right much fainter Mercury come to within less than a degree of each other at their closest.

If you’ve never seen the elusive (some prefer to call it “shy”) planet Mercury, here’s a perfect chance to finally glimpse it! The often-told story that the famous astronomer Copernicus never saw it, so rapidly does it move and so close does it stay to the Sun, is apparently only a myth. But unfortunately this story has discouraged many sky-watchers from ever trying to see it. Actually the planet is relatively bright and quite obvious when at one of its frequent elongations east or west of the Sun in the evening or morning sky, respectively. The trick is knowing just when and where to look!

Mercury and Venus are the two fastest moving of all the planets in their orbits about the Sun, which translates into their apparent rapid movements as seen in the sky. As a result, in addition to their conjunction on the 10th itself, the relative motion of both planets will be noticeable for some time both before and after the actual event—with Venus climbing noticeably higher in the sky and Mercury dropping noticeably lower towards the horizon from night to night. Again, it’s certainly easy to see why the ancients called these restless worlds “planets” which means “wanderers” in Latin.

Before closing, while out on the evening of the10th notice ruddy Mars high to the upper left (north and east) and the hair-thin crescent Moon to the west of the Venus-Mercury pair. They will both play a role in next month’s spectacular triple conjunction! (Be sure to see the February Sky Talk for more about this.)

— James Mullaney
Former assistant editor at Sky & Telescope magazine & author of nine books on
stargazing. His latest, Celebrating the Universe!, is available from HayHouse.com.