Sky Talk April 2012: Venus Kisses Pleiades Star Cluster!

As mentioned in last month’s column, following its striking conjunction with the planet Jupiter, radiant Venus made a beeline right for the famed Pleiades Star Cluster (popularly known as “The Seven Sisters”). On the evenings of April 2nd and 3rd, our lovely “Evening Star” will move through (across) portions of this glittering stellar jewelbox, the combo looking like a brilliant gem set amid sparkling blue-white diamonds!

Be sure to mark Monday and Tuesday evenings, April 2nd and 3rd, on your calendar. About 45 minutes to an hour after sunset if skies are clear, you’ll see the brilliant planet Venus hovering in the western sky just under (or on top of, depending on your latitude) the lovely Pleiades Star Cluster. While an intriguing sight with the unaided eye (a matter of how sharp your vision happens to be!), this pairing will be an ideal target for your 7×50 or 10×50 Edmund binoculars, which will easily encompass both planet and cluster with plenty of sky around them. So too will a wide-field telescope like the Edmund Scientifics’ Astroscan with its amazing 3-degree field (that’s six Full-Moon diameters of sky!) at 16x.

The Pleiades itself is the best-known and brightest open cluster in the sky, containing dozens of stars as seen in binoculars — and hundreds viewed in larger telescopes. Venus’ slow motion across the cluster will be noticeable over a period of hours, especially in the latter glasses. There’s also the possibility of seeing Venus actually cover up (or occult) and then uncover some of the cluster members, but this will definitely require a telescope using enough magnification to show its brilliant disk well (50x to 100x is recommended here). If you see the planet close to a star, carefully watch it to determine if it’s heading right for it. The chance of actually witnessing an occultation is remote (none are predicted) and depends heavily on your geographic location. But just seeing Venus in close proximity to the cluster’s stars will be exciting in itself.

There’s an added treat here for skywatchers. It turns out that Venus will be at its greatest brilliancy in April. And contrary to logic, it’s not brightest when fully illuminated — because it’s then on the opposite side of the Sun from us, and quite distant and small. It actually appears the brightest in our sky when in the crescent phase! That’s when it’s on “our side” of the Sun, relatively close to us, and displays a huge crescent which reflects much more sunlight Earthward than does its tiny disk when fully illuminated. The bottom line here is that the crescent Venus will be a beautiful sight in telescopes even at low powers, and it can also be glimpsed through carefully-focused and steadily-mounted (or image-stabilized) binoculars.

One other April event worth mention is that of the annual Lyrid Meteor Shower, which peaks on the night of the 21st-22nd. While not a rich display, it has on occasion surprised observers with many more “shooting stars” than normal. And this time, maximum occurs on the same night as the New Moon, so moonlight will not interfere at all with visibility.

— James Mullaney
Former assistant editor at Sky & Telescope magazine & author of eight books on stargazing.

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