Sky Notes for the Summer of 2020 Peter Morris (all images from Stellarium unless stated) The Problem is the short summer nights. There is no astronomical darkness in June: on 21 June, nautical night (between astronomical night and civil night) starts at 23.24 BST and ends at 2.40 BST. Furthermore as the sun is high in the sky in the day, the ecliptic is low at 1 am BST. This makes it difficult to see planets and the various interesting nebulae in Sagittarius and Scorpius. Southern sky at 1 BST on 22 June: NB: Sagittarius, Scorpio and major planets are all less than tree height above the horizon. But situation improves by August, on 15 August, astronomical night begins at 22.44 BST and ends at 3.23 BST. It is therefore best to observe planets and the brighter double stars which can be seen in the twilight. Use very bright stars such as Vega and Arcturus to set up your go-to beforehand. At least it should be warm! Comets Comet Atlas may have fallen to bits, but there is still Comet Swan. It may get as bright as magnitude 3 in late May and June which means it should be visible even in Havering, but it will be close to the horizon, hardly more than 7 degrees high, and of course we will have light skies which are particularly problematic for comets. At the end of May it will be near the bright star Capella in the north and during June it will slowly travel across the constellation of Auriga while at the same time approaching the horizon. It is best seen about 1 am or a bit later. Comet Swan on 1 May 2020 from Indonesia By Christian Gloor - https://www.flickr.com/photos/christian_gloor/49840472451/, CC BY 2.0, https://commons.wikimedia.org/w/index.php?curid=90087262 For a viewing chart, see here: https://www.skyatnightmagazine.com/advice/skills/comet-c- 2020-f8-swan-visible-how-to-see-it/ Planets Venus Venus will be bright in the evening twilight until the end of May, but it then becomes close to the sun and lost to view. It will return in the morning twilight in late June and reaches maximum brightness on 8 July when it will be near Aldebaran. Two interesting things happen with Venus in this period. On 21 May, Mercury will be directly below Venus, on the 22nd they will be level and on the 23rd Mercury will be above Venus. This is a good way of finding Mercury, find Venus and then you will find Mercury. But you will need a very clear view of the western horizon as Venus will only be 7 degrees high at best. This is why I have used the Ocean landscape option in Stellarium. Mercury and Venus on 21 May at 21:44 BST. Mercury is just under 7 degrees high. The bright star above them is Alnath (Beta Taurii). Mercury and Venus on 22 May at 21:44 BST. Mercury is about 7.4 degrees high. Mercury and Venus on 22 May at 21:44 BST. Mercury is just under 8 degrees high. On 19 June, the Moon will occlude Venus. Venus will disappear from view about 8.41 and reappear on the dark side of the Moon an hour later. This will be in the daytime but should be visible through binoculars or a telescope (be careful not to point your binoculars or telescope near the sun). Both the Moon and Venus will be very thin crescents. Position of the Moon and Sun at 8:40 BST on 19 June. Venus going behind the thin crescent Moon at 8.41 BST on 19 June. Venus emerging from the dark side of the moon at 945 BST on 19 June. Other Planets Jupiter, Saturn and Mars have been hugging the eastern horizon at dawn for some time now, but as summer approaches, they are seen earlier in the night but still near the horizon. Jupiter will be at opposition on 14 July and Saturn will be at opposition on 20 July. But Mars will not reach opposition until October. In late July Jupiter and Saturn will be fairly bright and due south at midnight, but very low in the sky and dimmed by extinction. Mars will not be obvious until about 2.30 to 3 am but will seem brighter as it will be higher in the sky than the two gas giants. Venus will also be prominent. But both planets will be the dawn twilight by then. Jupiter and Saturn almost due south at midnight BST on 21 July, but very low Mars almost due south at 3:45 BST on 21 July with Venus rising, but dawn is near The Deep Sky The summer sky is dominated by the Summer Triangle, made up of three very bright stars – Vega, Deneb and Altair – and easily visible between now and late autumn. The summer triangle at midnight on 20 July above Saturn and Jupiter Within this triangle one can see two interesting bright planetary nebulae: M57 the Ring Nebula in Lyra, almost at one of the edges of the triangle and M27 the Dumbbell Nebula in Vulpecula. It is important to note that to the eye they do not have any colour (unlike in images). M57 is like a smoke ring from a cigar and M27 is a pair of overlapping pale grey equilateral triangles and looks huge in a telescope, it is very easy to see unlike M57 which needs a high magnification. M57 (Ring Nebula) by William Wood (HAS) M27 (Dumbbell Nebula) by Martin Gill (HAS) Near M27 is the asterism Collinder 399 or the Coathanger as it is best known, it is more or less on the same level as M27 but to its right (or west) between Albireo and Altair. It is best seen in binoculars or a finderscope rather than a telescope. It is not actually a star cluster but an optical illusion. The Coathanger (aka Brocchi’s Cluster or Collinder 399). From Wikipedia. By Petr Novák (http://astrofotky.cz/~karneades) M27 is at very bottom of this chart on the left, Albireo is the bright star almost in the middle of the chart and M57 is at the bottom edge of Lyra between Beta Lyrae (Sheliak) and Gamma Lyrae (Sulafat). The Coathanger is at the middle of the bottom edge of this chart. Right in the middle of the Summer Triangle is the famous gold and blue double star Beta Cygni or Albireo. By Jeremy Perez (http://www.perezmedia.net/beltofvenus). Used with permission. If you look at Vega with binoculars or a finderscope, you will see a pair of stars to its east or left, some people can even separate them with the naked eye. This is the famous double- double, Epsilon Lyrae, which under high magnification, about 100x, both split into very tight doubles. These doubles are at right angles to each other, so check yourself to see if it is easier to resolve doubles which are above one another or side by side. Sky chart for Lyra: M57 is at the bottom and Epsilon Lyrae is the left of Vega. By Jeremy Perez (http://www.perezmedia.net/beltofvenus). Used with permission. June is a good time to see two wonderful globular clusters. M13 is in the square or keystone of Hercules and M5 is directly below M13 in Serpens Caput, but it is still relatively high up in June. Which do you think is the more impressive? There several other globular clusters but they are all low in the sky. M13 (the Great Cluster in Hercules) is at the top right of the chart and M5 is at the bottom right. M13 by Martin Gill (HAS) M5 by Andrew Relf (HAS) Galaxies are hard to see in light-polluted Havering, but the summer is a good time to view two bright galaxies in Ursa Major which is fairly low in the sky and due north. M81 the large spiral galaxy called Bode’s Galaxy which is a little bit hard to see as the light is spread out across the spiral, and M82 the Cigar Galaxy which is easier as it is more concentrated. Note the dark area in the middle of the galaxy which is a major star-forming region in this violently active galaxy. Draw a line between Dubhe in the Plough and Polaris. The two galaxies can be found one third of the distance between Dubhe and Polaris but lower down (or further west). M81 by Martin Gill (HAS) M82 by Martin Gill (HAS) I have already mentioned Albireo and Epsilon Lyrae, and I will end with four good doubles. Theta Serpentis or Alya in Serpens Cauda to the right (or west) of Altair. Serpens (the Serpent) is divided into two parts which are separated by the large constellation of Ophiuchus: Serpens Caput (the Head of the Serpent) in the west and Serpens Cauda (the Tail of the Serpent) in the east. This is a bright wide double which is basically white, but one can detect delicate tints in the stars, perhaps green or pink, see what you think. By Jeremy Perez (http://www.perezmedia.net/beltofvenus). Used with permission. Then there is Xi Scorpii, which is a fairly tight yellow and blue double which is high up despite being in Scorpius, actually being above Libra. There is the bonus of a dimmer yellow and yellow double called Struve 1999 in the same telescopic field. By Jeremy Perez (http://www.perezmedia.net/beltofvenus).