Spring is moving steadily onto Summer and the frosts are diminishing. May is a month where we lose the night time and are simply bathed in astronomical twilight as the Sun is approaching its highest northerly declination and never retreats far below the horizon. This same physics leads to the land of the midnight Sun as your latitude increases. To some the end of May is the death knell for serious observing until late Summer but there is the alternative view; the medium to bright objects are still readily visible, the nights are warmer and you can spend time either just starring at the sky with friends at the end of the barbecue or in getting to know your kit better and feel more comfortable using it.
The Moon starts the month approaching first quarter in the south west around 10pm. Its path through Cancer, Leo and onto Virgo, as it approaches full Moon on 10th May, will flood the usual Messier delights in this part of the sky with light but watching the Moon’s terminator progress from hour to hour and day to day is a pleasure. As May reaches mid-point and beyond, the Moon moves into the morning sky having less effect on observing dimmer objects. Only the dim nebulae will remain elusive during the month. Last quarter is on the 18th and New on 25th. Hence the weekends on 20/21st and 27/28th will be best for getting scopes out if limited in opportunities.
Jupiter is in the evening having passed opposition in April and remains the predominate object to the south all the way through the month. Sketching the positions of Gallilean moons from hour to hour and day to day or using a camera behind the eyepiece will reprise the work that led to the acceptance of the heliocentric solar system and as a science project allow you to determine the orbital periods of each moon. Depending on your telescope, you may be able to make out detail on the equatorial belts and again watch over a number of visits (hour by hour) to see them move and see how rapidly Jupiter spins on its axis. Like the Moon, Jupiter is so bright that it will take some time to get dark adapted again after observing so plan ahead if you want to look at lots of different types of object.
Mars remains close to the setting Sun throughout the month but remains visible for an hour after sunset. This separation diminishes to about 50% by the end of the month so best to catch it early. From June until late Summer, it will be lost to the glare of the Sun.
Venus starts the month as a morning star rising a couple of hours before dawn. Mercury trails it near Uranus only a hour before sunrise. It reaches greatest western elongation early in the month and is then beyond its best until September time. Things move on and by the end of the month Earth’s movement around the Sun has brought Venus closer to Uranus as morning objects.
Neptune resides quietly in Aquarius as a morning object rising around 4am.
With Cassini commencing its last 22 death defying orbits this week just gone and becoming the fastest man made object in the solar system, Saturn is giving up its secrets one by one. Rising around midnight, the ring structure is visible in modest telescopes and is still opening out as we approach opposition in June and the best observing of the year.
The Eta Aquarid Meteor Shower peaks on the 6th and 7th May. The radiant is the Aquarius, low in the sky to the south east and visible in the morning sky and so with the combination of the Moon will make counts this year low; sometimes counts reach 30 per hour. Well worth looking for if you are an early bird.
May’s sky is easily recognisable with Leo due South, Ursa Major overhead and the Summer constellations rising in the east. Although conditions are not ideal at the start of the month, the high density of deep sky objects in and around Coma Berenices and Virgo are well worth having a look at in the south at their highest annual position in the sky. Have a look at the cluster of red objects in the web site’s planisphere to get a feel of where they are in the sky.