The New Moon for May occurs on Thursday, May 13th. This will make the Weekend of May 15-16 the best weekend for dark sky observing.
Mercury will reach it’s best morning view on May 25th, when it reaches it’s Greatest Western Elongation and is 25°7’46” from the Sun. Note the red line is the orbit of Mercury and the green line is the Ecliptic.
Mercury begins May in the constellation Aries (The Ram), and on May 9th, Mercury crosses into the constellation Pisces (The Fish). On May 14th, Mercury moves into the constellation Cetus (The Sea Monster) until May 22nd when it returns to the constellation Aries.
On May 9th, Jupiter rises less than 5°10’ of the waning, crescent Moon and less than 4° of the planet Uranus. Jupiter continues to move closer to Uranus throughout the month of May, ending May less than 1° of Uranus. Jupiter and Uranus will reach conjunction on June 7th.
Saturn is located in the constellation Virgo (The Maiden) until December 2012 and is observable during the evening to mid-night hours of May. Saturn sets around 4:20 am (PDT) at the start of May, and by the end of the month, sets around 2:20 am (PDT).
Uranus is located in the constellation Pisces (The Fish) until May 2012. This month, Uranus can be observed in the morning hours before sunrise. At the start of May, Uranus rises around 4:15 am (PDT) and by the end of the month, Uranus rises around 2:20 am (PDT) and is less than 1° from Jupiter. Jupiter and Uranus will reach conjunction on June 7th.
Neptune is observable in the morning hours of May. At the start of May, Neptune rises around 2:55 am (PDT) and by the end of the month, Neptune rises around 12:50 am (PDT). Neptune is located in the constellation Capricornus (The Sea Goat) until August.
Pluto is located in the constellation Sagittarius (The Archer) until the year 2023. Pluto can be observed in the mid-night to morning hours of May. Pluto rises around 12:25 am (PDT) at the start of May and by the end of the month, Pluto rises as early as 9:20 pm (PDT).