It has been a busy few weeks in the night sky with opportunities to see noctilucent clouds and the Neowise Comet. There is lots to see in August, with it being a great time to view the Milky Way, the Perseids meteor shower and various planets. 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.
The whole of the summer Milky Way is stretched across the sky in the South from Cygnus, high in the sky near the zenith (that point that is directly above you at the very centre), past Aquila, with the bright star Altair, to part of the constellation of Sagittarius close to the southern horizon, where the patterns of stars known as the ‘Teapot ‘ may be just visible. This area is rich in nebulae and both open and globular clusters. Between Alberio and Altair lie two small constellations of Vulpecula and Sagitta, which can be distinguished from the Milky Way using binoculars. Still using binoculars, between Sagitta and Pegasus to the east lie the highly distinctive five stars that form the tiny constellation of Delphinus. Below Aquila, mainly in the star clouds of the Milky Way, lies Scutum, known for its bright open cluster, M11 or the ‘Wild Duck Cluster’ readily visible with binoculars. To the southeast lie the two zodiacal constellations of Capricornus and Aquarius.
The Plough, which is part of Ursa Major is now the ‘right way up’ in the northwest, but some of the fainter stars are difficult to see. Bootes stands almost vertically in the west, but pale Arcturus is sinking towards the horizon. Higher in the sky you can see Corona Borealis and Hercules clearly. In the northeast Capella is clear to see, but much of Auriga is below the horizon. Higher in the sky is Perseus and later in the night and later in the month stunning Pleiades rises above the northeastern horizon. Between Perseus and Polaris lies the constellation of Camelopardalis. Higher still, both Cassiopeia and Cephus are easy to observe even though Cassiopeia is bathed in the band of the Milky Way. Pegasus and Andromeda are now above the eastern horizon with Pisces climbing into view.
Perseids Meteor Shower
August is the month when one of the best meteor showers of the year occurs, the Perseids. This long shower started on the July 16th and continues until August 23rd, reaching its maximum on 11th-13th August. The Perseids originate from the Comet Swift-Tuttle (the great Comet of 1862) which is a large periodic comet with an orbital period of 133 years. Its last visit was in the early 1990’s and led to increased activity during 1991, 1992 and 1993 when one of its meteoroids damaged the Olympus satellite leading to its ultimate demise. Cosmonauts onboard Mir around the same time reported hearing pings which were believed to be meteoroids impacting on the stations hull.
The best time to observe the Perseids is after midnight when we are on the side of the Earth facing forward along its motion around the Sun where we run into more meteoroids. Scientists have estimated that the total mass of material contained within the Perseid stream is over 10 billion tonnes.
After spending the first half of 2020 in the evening sky, Venus is now a brilliant beacon in the morning sky and will remain so into September. Jupiter makes a fine appearance, late in the evening, at the beginning of the month coming together with Saturn just above the south-southeastern horizon with the Moon. In the second week the Moon passes Mars in the east-southeast around midnight to 1 am. At the end of the month in the late evening there is another opportunity to see Saturn and Jupiter joined by the Moon.
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 up so that it obscures part of your view. The width of your hand is 10 degrees and holding just one finger is two degrees.
4th Aug Moonrise 22.00 – look out for illusion; Moon appears artificially large.
13th-24th Aug Delta Aquariid meteor shower.
11th–13th Aug Peak of the Perseid meteor shower, best after midnight.
19th Aug New Moon
20th Aug Best night for viewing the Milky Way from a dark location.
28th Aug Jupiter 3.7 degrees SW from a waxing gibbous Moon.
29th Aug Saturn, as the sky darkens Saturn appears 4 degrees NW of Moon.
31st Aug Best sightings of Mars are at 04.00 looking South through Pisces.