May is the first month when the constellation of Orion is absent from the night sky altogether, and of the prominent winter stars only Capella in Auriga the Charioteer and Castor and Pollux in Gemini remain above the western horizon. The Plough or Ursa Major (the Great Bear) is still more or less overhead with the pointers pointing to the North Star. The ‘W’ of Cassiopeia is now very low down although still easily visible in the north western sky.
It is also a good month to look for another of the circumpolar constellations; Draco the Dragon. Circumpolar constellations such as the Plough, Cassiopeia and Draco are visible all year around; this is because these stars are above the Earth in space.
Draco is represented by a stream of stars that winds its way around the North Star, so although it has no really bright stars it is still quite easy to identify. The stream starts roughly between the pointers of the Plough and the North Star, then winds its way past the Plough making off in the general direction of Cepheus.
It then turns and ends up at the ‘Dragon’s Head’, a quadrilateral of four stars near the bright star Vega, which is one of the stars that forms the Summer Triangle.
There is one notable star to mention in Draco and this is Thuban, which is not prominent in brightness and is located between Mizar, in the Plough, and the orange star Kocab, in Ursa Minor.
Use the Plough, to draw a line down following the curve of the handle to the bright orange star Arcturus in Bootes the Herdsman which is now very high up. Your downward curve will take you to Spica in Virgo the Virgin. Both Arcturus and Spica are almost due south.
High in the South West can be found Leo the Lion with its bright star Regulus, at the base of a distinctive looking ‘backwards question mark’ of stars. The small quadrilateral of stars that form Corvus the Crow is still quite conspicuous low in the south, while further to the south west and low down is the orange star Alphard, the brightest star in the constellation of Hydra the Water Snake. Alphard is often called ‘The Solitary One’ because of the lack of bright stars near it.
In the North East, two of the stars that form the summer triangle can be seen; Vega, in Lyra the Lyre, has reached a respectable altitude and Deneb in Cygnus the Swan is now becoming noticeable. The third point in the triangle, Altair in Aquila the Eagle, has yet to appear.
This month Venus is the queen of the evening skies. Blazing at magnitude –4.0 in the north west and setting almost three hours after the Sun. on the 17th and 18th of May, there will be a glorious sight low in the western sky, with the crescent Moon up close and personal to Venus.
Diametrically opposite around the horizon, in the south east, the Evening star has competition from Jupiter. At a glorious magnitude –2.5, the giant planet lies in the constellation of Libra, and is above the horizon all night long. The gas giant is at opposition on the 9th of this month, i.e. Jupiter is opposite to the Sun in the sky. Because the planets orbits are not quite circular, we are closest to Jupiter
the following day, at 658 million kilometres. You can use your binoculars or a low power telescope to locate the four largest moons of Jupiter.
Next in the planetary line up, Saturn rises in the south east around midnight. At magnitude =0.3, the ring world sits among the stars of Sagittarius.
Mars begins the month in Sagittarius, but speeds into Capricornus by mid month, brightening from magnitude-0.4 to –1.2. The red planet rises about 2am.
Faint Neptune, magnitude +7.9, rises about 4am and can be found in Aquarius.
Mercury and Uranus are lost in bright daylight this month.
There is one meteor shower this month, called the Eta Aquarids. This shower, which will peak in the early hours of the mornings of May 5th and May 6th, is best seen from the southern hemisphere; however, on either of those mornings a couple of hours before sunrise you might see around 10 meteors per hour. This meteor shower is the remains of Halley’s comet.
Phases of the Moon for May
Last Quarter 8th
New Moon 15th
First Quarter 22nd
Full Moon 29th