By Larry Rotolo, San Diego Entertainer – May 17, 2013
From the latter part of May and continuing for a month, an amazing display of planets will play itself out near the horizon in the west-northwest part of the sky. Beginning each night right after the sun sets around May 19, a “dancing with the stars” exhibition is put on by the three brightest planets as seen from Earth: Venus, Mercury and Jupiter.
In 2013 we will get to see the most compact three-planet grouping visible without binoculars for the next 13 years. The planets will not appear this close together again until the year 2026! Added to this sight will be a beautiful apparition of Mercury.
The three worlds will appear to skip about one another. The alterations in their positions in the early evening sky will be visible to the naked eye night by night. Venus and Jupiter will be very close together by May 28. Afterwards, Venus will move in a northwesterly (to the upper right) direction compared to Jupiter. At that point it will be six times as bright as Jupiter.
Mercury becomes possible to observe at Venus’s lower right around May 19th. It appears closer to Venus each evening until May 24th, when it’s just 1⅓° to the upper right of Venus. From May 24th to 29th, Venus, Jupiter, and Mercury will all fit within a 5° circle. Thus, they can all be viewed simultaneously through binoculars without moving the glasses.
The pattern is most compact on May 26th, when all three planets are close enough to each other to fit in a 2˝° circle. Jupiter appears right next to Venus on the 27th, and after that it slowly pulls down and right of Venus, disappearing from view in early June. But Mercury is only now in the major phase of its apparition, flying over Venus until June 7th.
At that point , the planet will start to gradually move downward, nearing Venus again. However, Mercury has started to grow dimmer, as it must while engaged in an evening apparition. It will diminish little by little, the fading speeding up by June 15. Mercury had been almost as bright as Jupiter when the apparition started, but will shrink to a tenth of that brightness by the 20th of June.