During May of 2011, four bright planets will engage in a rare and fascinating dance with each other in the morning sky.
Mercury, Venus, Mars and Jupiter will be involved in a series of conjunctions, joined at the end of the month by a very thin, waning crescent moon. This could be referred to as a “celestial summit meeting,” or a series of summit meetings throughout the month of May.
Twice during May three planets will converge to form a “trio,” which is when three planets fit within a circle with a minimum diameter of 5 degrees.
On Wednesday, May 11, Mercury, Venus and Jupiter will converge within 2.05-degrees of each other, followed just 10 days later by another trio, this time formed by Mercury, Venus and Mars, who will form a 2.13-degree circle. Later in the month, on three successive mornings, May 29th, 30th, and 31st, the crescent moon will be visible, sweeping past Jupiter, Mars, Venus and Mercury stretched out across the eastern sky from upper right to lower left.
The tragedy of this unique conjunction is that it will be incredibly difficult to see for those north of the Equator. Their elongations from the sun will range from 18 degrees to 26 degrees, which should place them all in dark skies. Unfortunately, during May, as seen especially from mid-northern latitudes, the ecliptic is oriented at a shallow angle relative to the eastern horizon at dawn. As a result of this, the moon and planets will rise into view during late twilight and will lie very low to the east-northeast horizon by sunrise.
But coming above the horizon so near to sunrise will also mean that you’ll have a fighting chance of catching Venus and Jupiter with unaided eyes. Mercury is harder to see although there’s a slim chance of visibility, but without binoculars, Mars will be almost impossible to glimpse.
