The moon at perigee (closest approach to Earth) occurs May 5, which causes large oceanic tides. Not that it makes a difference in central Canada, but the movement of the ocean鈥檚 water is a lesson in planetary motion 鈥� it鈥檚 the sun, moon and gravity at work to make the sloshing motion that is the tides. There will be especially high tides for a few days as the sun and nearby moon combine their pull on the oceans. May 8, Aldebaran, the bright star in Taurus, is occulted for viewers in the Eastern Hemisphere. For us, it鈥檚 a close approach of half a degree. May 15, Jupiter is two degrees north of the moon. Full moon is May 21.
Mercury is involved in a special event this month 鈥� a transit, where the speedy planet moves in front of the sun for a few hours. This happens May 9, and it will be the subject of much interest, as it occurs somewhat rarely 鈥� only 13 or 14 times per century. Only transits of Mercury or Venus are possible as seen from Earth, since those inner planets are just that, innermost between Earth and the sun. For viewers here in Saskatchewan, the event is in progress just after sunrise, beginning at 5:12 a.m. sunrise for locations at 50 degrees north latitude is at 4:25 a.m. Following that momentous transit event, Mercury will grace the eastern morning sky after May 19.
Venus can鈥檛 be seen this month.
Mars rises near sunset and crosses the sky all through the night. This month is the closest Mars gets to Earth for another 2.2 years, so surface details may be visible to sharp-eyed observers. This is the time to check out the north polar cap to determine size. Watch for dust storms that often encircle the Red Planet and feast upon the dark and light patches that bear such romantic names as Syrtis Major, Elysium and Meridiani Sinus.
Jupiter is well placed for viewing in the evening eastern sky, ending its retrograde motion May 9, beginning to move eastward again in proper motion. Watch for the moon nearby May 15.
Saturn rises in late evening, also well placed for those telescopic 鈥淲ow!鈥� moments. Nothing quite matches the sight of Saturn鈥檚 rings silhouetted against the inky blackness of outer space.
Uranus is poorly placed, low in the eastern morning twilight.
Neptune is even more poorly placed, rising just about sunrise, and then quickly fading in the daylight sky.
鈥� 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 the Society鈥檚 president, assistant editor and a contributor to the renowned Observer鈥檚 Handbook, and production manager of the bi-monthly RASC Journal. He was given the RASC Service Award at the 2012 General Assembly in Edmonton.
