Sky Talk July 2007: Spectacular Conjunction of Venus & Saturn

After drawing ever-closer to each other in the evening sky over the past couple of months, the radiant planet Venus and the ringed planet Saturn finally meet in a stunning conjunction as July opens. Their cosmic embrace offers a visual feast for observers not to be missed — whether using the unaided eye, binoculars or a small telescope!

Shortly after darkness falls on the evening of July 1st, Venus and Saturn will dominate the western sky as they appear to hug each other as seen from our perspective here on Earth. At their closest approach around 9 p.m. EDT they will lie less than a degree apart, with fainter Saturn just to the upper right (northwest) of Venus.

Following their close encounter, these restless worlds will separate from each other over the next few weeks, with Venus moving noticeably eastward each night. By July 16th, it will be just 2 degrees south of first-magnitude Regulus in Leo. (Use the Edmund Scientifics Star & Planet Locator to identify the star and constellation, both of which will appear low in the western sky during twilight at that time.)

The planetary pairing itself will be especially stunning as seen in binoculars and low-power, wide-field telescopes like the Edmund Scientifics’ Astroscan reflector. With its spectacular 3-degrees (or six full-Moon diameters!) of sky coverage at 16x, it will provide an especially dramatic view of the conjunction itself. And then as the planets slowly separate over the coming evenings, they will eventually pass out of the telescope’s field and no longer fit together within the same eyepiece view — offering a dramatic demonstration that planets do, in fact, noticeably move from night-to-night!

But there’s still more. Telescopes and spotting scopes magnifying 15x or higher will show Venus to be in its crescent phase during July, which grows noticeably larger in apparent size but thinner as the month progresses before the planet finally disappears into the afterglow of sunset. Note that steadily-held or image-stabilized binoculars can actually show the crescent as well to a trained eye at magnifications of 10x or greater.

Also worth noting is that the planet will appear at its greatest brilliancy on the evenings of July 11th and 12 (attaining maximum brightness even though in the crescent phase, for the reason explained in the June installment of Sky Talk). As an added treat, using magnifications of at least 30x or more on a good-quality telescope will reveal Saturn’s amazing ring system. The planet is moving in its orbit toward the other side of the Sun from us in July, resulting in its image being much smaller than it normally is when close to us.

In addition, the rings are no longer wide open as they have been for the past several years. These two conditions combine to make it a bit of a challenge to glimpse the rings at low power, but they are definitely still there to be seen. On the night of the conjunction itself, observers using standard telescopes having fields of view of a degree or more at magnifications of 30x to 50x will have the thrill of seeing both Saturn with its rings and the crescent Venus in the very same eyepiece field!

–James Mullaney
Former assistant editor at Sky & Telescope and author of five books on stargazing.

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