For those not active in astronomy circles, there is a website called Cloudy Nights for all things astro related i.e. where astronomers can go to talk about astronomy when there are “cloudy nights”. Each month, they publish the detailed Celestial Calendar (by Dave Mitsky). Here are some of the highlights for May (times converted to Ottawa time):
- May 4/5th — The peak of the Eta Aquarid meteor shower (20 per hour for northern hemisphere observers) occurs at 03h00 (May 5); the Moon, Mars, and Pluto lie within a circle of diameter 4.81 degrees at 19h00 (May 5)
- May 7: Last Quarter Moon occurs at 22h09 (7th);
- May 8: Jupiter is opposition (angular size 44.8”, magnitude -2.5) at 20h00
- May 15: New Moon occurs at 07:48; the Moon is 8.7 degrees south-southeast of the bright open cluster M45 (the Pleiades or Subaru) in Taurus at 18:00; Venus is at perihelion (0.7184 astronomical units from the Sun) at 19:00
- May 21: First Quarter Moon occurs at 23h49;
- May 29: Full Moon, known as the Milk or Planting Moon, occurs at 10h19; the Moon is 8.8 degrees north of Antares at 15h00
- May 29/30: Mercury is 4.5 degrees south-southeast of M45 at 03h00 (30th)
For the planets:
During May, Venus shines prominently in the evening sky. It increases in angular diameter from 11.5 arc minutes to 13.1 arc seconds while decreasing in illumination from 88% to 81% during the course of the month. Its altitude at sunset increases from approximately 24 degrees to 27 degrees. A thin waxing crescent Moon passes five degrees south of it on May 17th.
Mars doubles in brightness to magnitude -1.2 and grows in apparent size by one third to 15.1 arc seconds during May. It rises just before 1:30 a.m. local time as the month begins. Mars rises a bit after midnight by month’s end.
When Jupiter reaches opposition on the night of May 8th, it will rise at sunset and set at sunrise. A shadow transit by Io begins at 10:56 p.m. EDT on May 7th, followed by a transit of Io two minutes later. On the night of May 8th, Io, Europa, and Callisto lie to the east of the planet and Ganymede lies to the west. Io begins to transit Jupiter at 10:37 p.m. EDT on May 30th and is joined by its shadow at 11:07 p.m. EDT.
Saturn lies less than four degrees northeast of the third-magnitude star Lambda Sagittarii and 1.7 degrees north of the bright globular cluster M22 on May 1st. The Ringed Planet’s retrograde motion takes it to position 1.8 degrees northwest of M22 by the end of May. The waning gibbous Moon passes less than two degrees north of Saturn on May 4th.
And then there are general links to planning tools and challenge lists for the month:
Top ten deep-sky objects for May: M3, M51, M63, M64, M83, M87, M104, M106, NGC 4449, NGC 4565