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.
The Full Moon for May occurs on May 27th and is known as the “Full Strawberry Moon” or “Full Rose Moon.”
Mercury appears to the morning hours on May 5th and will be visible as the Morning Star for the rest of the month.
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 12th as Mercury ends its retrograde motion, the waning, crescent Moon will pass less than 6°40’ of Mercury.
Venus is the Evening Star All Month and is visible after sunset.
Venus begins this month in the constellation Taurus (The Bull) until May 19th, when it crosses into the constellation Gemini (The Twins).
On May 21st, Venus passes less than 0°50’ from the Open Star cluster known as M35.
On May 27th, Venus is in near conjunction with the Double Star Mensuta, in Gemini, and passes less than 0°25’ of Mensuta.
Mars is still in great position for observation in the evening this month. At the start of May, Mars sets around 2:15 am (PDT) and by the end of the month, Mars sets around 12:50 am (PDT).
Mars begins the month in the constellation Cancer (The Crab) and on May 12th, Mars crosses into the constellation Leo (The Lion).
Jupiter is observable in the morning hours of May. At the beginning of May, Jupiter rises around 4:05 am (PDT) and by the end of May it rises, less than 1° away from Uranus, around 2:20 am (PDT).
Jupiter starts the month in the constellation Aquarius (The Water Bearer), But crosses into the constellation Pisces (The Fish) on May 2nd where it remains for the rest of May.
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).
On May 22nd, the waxing, gibbous Moon passes within 7°45’ of Saturn.
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).