Rare Triple Conjunction Graces May Skies

by Rod Kennedy

One advantage to observing planets is that a telescope is not required to see them (at least not the five “classical” planets known to the ancients.  All that is required is a general knowledge of the constellations or an “app” for your mobile device.  Binoculars are helpful in locating fainter planets; and telescopes take you up close and personal.  May is a great month for observing planets, but one you will have to see before the end of the month.

Of the five “naked-eye” planets, 4 are visible in May.  The first (and most challenging to see) is Mercury.  Mercury is found in the western sky just after sunset.  In mid-May Mercury will be very low on the horizon, but will steadily climb higher into the sky by the end of the month.

Above Mercury, and the brightest object in the twilight sky is Venus.  Like Mercury, Venus will be low early in the month but climb higher as the month progresses.

Higher still is Jupiter.  Jupiter is a little less bright than Venus but should be easy to spot in the sunset twilight.  However, as the month wears on and Earth continues its orbit around the sun, Jupiter will slowly appear to creep into the glare of the sun.  Jupiter won’t be visible again until autumn.

While it is exciting to see the planets in a nice, neat line, a far more interesting (and rare) event occurs on the evening of May 26.  On this evening the planets Mercury, Venus and Jupiter will form a close triangle with Venus at the bottom, Jupiter to the left and Mercury at the top.  This event is known as a triple conjunction.  Each planet will be about 2 degrees from its neighbors.  By May 30 the three will again be in a line with Jupiter being the lowest, Venus in the middle and Mercury the highest.

Conjunctions of this type are fairly rare.  According to NASA the last one like it occurred in 2011 and the next won’t occur until 2015.  However, if you miss out on this spectacular event, simply turn toward the East and look for the golden object 12 degrees to the left of the star Spica in Virgo the Maiden.  This golden point of light is the planet Saturn.  While Saturn is easily spotted with the unaided eye, a telescope is really needed to appreciate this stunning ringed world.

Observing the planets is a fun aspect of astronomy that does not require any special equipment or computer software or especially dark skies.  Once you learn to recognize their positions relative to the stars, you can “track” them year after year.  Sometimes they dominate the night sky, sometimes they are on the opposite side of the sun and therefore invisible.  However, like our ancient ancestors, once you get in the habit of observing the movement of the planets it becomes a life-long pursuit that can be done even when more detailed observing isn’t possible.

May 2013 Sky Chart

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