May: Planetary Logjam

May 2011

Planetary Logjam

By Calvin L. Chrisman

The month of May offers an opportunity to see the tightest alignment of planets in the sky in roughly the last twenty years. All during the month, just before sunrise, Venus, Jupiter, Mercury and Mars will be grouped together in the eastern sky. In the early part of the month, Mars and Mercury, which are the dimmest of the four, will be so low that you may need binoculars or a telescope to get a good look. Mercury will be hardest to spot all month, but Mars should be high enough to be seen easily by the last week of May.

Because of their closeness, the individual motion of each planet will be quite apparent and will offer interesting changes as they dance in the sky during the month. There will be two “trios” of planets to observe as the month progresses. The first will be Venus, Jupiter and Mercury which will be grouped within five degrees of one another between May 7 and May 15. During this period, on May 11th, very bright Venus and Jupiter will be just over one-half of a degree apart, with Jupiter to the upper left of Venus. This will be a spectacular sight if the sky is clear. The next morning, the four planets will be in their tightest arrangement – in a circle of about six degrees.

The next “trio” will begin to develop on the 15th and last until the 25th. This will consist of bright Venus and much dimmer Mercury and Mars. It will present its closest alignment on the 21st. The relative motion of these four planets will be both interesting and entertaining throughout the month of May. Who needs Dancing with the Stars when you can dance with the planets?

The other thing to watch for during the first two weeks of the month is the final flight of the space shuttle Endeavour which should launch on Friday, April 29. If the launch goes off as planned, Endeavour, which has flown over 103 million miles, will be docked with the International Space Station for most of the first two weeks of May. Its current orbit is such that there will be several opportunities to observe the combined vehicles pass overhead at approximately 225 miles high with a combined crew of thirteen. Endeavour will be piloted by Commander Mark Kelly, the husband of Congresswoman Gabrielle Giffords who will watch the launch.

You can check for the latest information on ISS passes, but two of note will be on the evenings of Friday, May 6 starting at 8:47 p.m. and Saturday, May 7 starting at 9:12 p.m. Each will last about five minutes. The pass on the 6th will start in the northwest and will move high to the northeast. The pass on the 7th will move from the west northwest to the southwest. With a clear sky, they will be very bright and easy to spot. This will be the next to the last shuttle flight and the last for Endeavour. Go out and see this historic event.

Clear Skies!


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