The month opens with the moon at last quarter, meaning it is three-quarters of the way through its month. New moon is May 9, plus this is an annular solar eclipse in the South Pacific. Remember that lunar and solar eclipses come in pairs (or triples) separated by two weeks, so we should have seen a lunar eclipse two weeks earlier. Sure enough, it occurred on April 25 in the South Pacific. This is an interesting year in that a second lunar eclipse follows the solar eclipse by two weeks on May 25. This one, though, hardly deserves mention, as the moon barely enters the Earth's shadow. As given in the RASC Observer's Handbook, "... such a shallow eclipse is only of academic interest since it will be all but impossible to detect."
On May 12, Jupiter skims by the north side of the moon; May 22, Spica is within a hair's breadth (an occultation in Polynesia); Saturn is within four degrees May 23; and Mercury is at a close 1.4 degrees May 24. The moon is full on May 24, as well, so viewing Mercury could pose a challenge for the naked-eye viewer.
Mercury will be absent for most of the month, but gradually appears low in the western evening sky by May18. Three close approaches make for an interesting sequence: Aldebaran is within seven degrees May 21; Venus, May 25, is 1.4 degrees north; and Jupiter is two degrees north May 27. All three planets are within three degrees between May 25 and 27, making an unusual observation. Use binoculars for the best view.
Venus is rather poor for viewing, being close to the horizon - better from the Southern Hemisphere. Look for the three planets in close conjunction late in the month, as noted above, in the western dusk.
Mars is not visible.
Jupiter is low in the western evening sky during the first part of the month, but fades away behind the sun as May closes. See Mercury above.
Saturn is visible all through the night, rising at sunset and setting at sunrise. The Ringed Planet is retrograding right now, apparently moving westward (but it is we who move more rapidly that causes this seeming unexpected discrepancy). Have a look at the image of Saturn's F ring at http://bit.ly/W8jnmr Not as smooth as we might think!
Uranus is low in the eastern morning sky.
Neptune also in the eastern morning sky, all but invisible because of the sun's glare.
- James Edgar has had an interest in the night sky all his life. He joined The Royal Astronomical Society of Canada in 2000 and is now editor's assistant and a contributor to Observer's Handbook, production manager of the bi-monthly RASC Journal and the society's national secretary. He was given the RASC Service Award at the 2012 General Assembly in Edmonton.
