There has been lots of look out for over the last few weeks, including Venus, Mercury and the International Space Station passing over us. Although we are approaching summer solstice and we are enjoying the light evenings there are still things to look out for; in particular the start of ‘season’ for viewing noctilucent clouds in the Northern Hemisphere which begins in early June. Vernon from the Callander and West Perthshire U3A Astronomy group shares what to look out for this month.
It is always helpful to have a star chart to follow when navigating and observing the heavens. A free star chart which also contains lots of additional observational notes is published monthly by Skymaps. Simply go to skymaps.com and scroll down to ‘Download the latest issue’. From here you will can download the northern hemisphere version and save it. This is then best printed double sided to an A4 sheet. It is worth noting that planets do not appear on skymaps.
In this note of astronomical events I have only included items that can be seen either with the naked eye or with a pair of binoculars.
Around the summer solstice a form of twilight remains in the south of the UK throughout the night. Here in Scotland the sky remains so light that most of the fainter stars and constellations are invisible. Even the brightest stars such as the seven stars that form the Plough in Ursa Major may be difficult to see.
The key feature to look for at these times are the highly distinctive electric blue noctilucent clouds. The word noctilucent is Latin, which means ‘night-shining.’ These are the highest forming clouds in the atmosphere occurring at altitudes of 80 – 85 km above the surface of the earth; occupying a layer of the atmosphere know as the mesophere. They are only visible only during the summer nights for one month to six weeks either side of the solstice, when the observer is in darkness and the clouds themselves remain illuminated by reflecting sunlight below the horizon due to their great height.
You can find out more information about noctilucent clouds on the Met Office website here.
Persistent twilight makes observing our skies difficult. Low on the horizon it is possible to see the red supergiant star Antares, the name means ‘Rival of Mars’. Higher in the sky is the large constellation of Ophichus, the ‘Serpent Bearer’ lying between the two halves of the constellation of Serpens; Serpens Caput, ‘Head of the Serpent’ to the west and Serpens Cauda, ‘Tail of the Serpent’ to the East.
Higher in the southern sky the three constellations of Bootes, Corona Borealis and Hercules are now better placed for observing than at any other time of the year.
Nights of interest
Some of the objects described below are expressed in degrees from the Moon. This is far less complicated to measure than you might think. To measure 10 degrees hold your hand up towards the sky at arm’s length and turn your hand so that it obscures part of your view. The width of your hand is 10 degrees and holding just one finger is two degrees.
5th June Full Moon. The first full moon of the summer months, you may hear it being called the ‘Strawberry Moon’ or ‘Rose Moon’.
8th June 17.21 hours. Jupiter is 2.2 degrees (one finger width at arm’s length) above the Moon.
9th June 02.12 hours. Saturn is 2.7 degrees above the Moon. Best time to view with Saturn (left and smaller) and Jupiter (right and slightly larger and brighter). This occurs low in the south-east about 10 degrees above the horizon (hand width at arm’s length) so a low horizon for the observer is essential.
12th June 23.55 hours. Mars is 2.8 degrees from the Moon.
13th June 03.00 hours. Mars is 2.8 degrees directly above the Moon.
20th June Summer Solstice – the longest day and shortest night of the calendar year.
29th June Moon is 7.8 degrees above Spica in Virgo.