In July the skies remain light and the opportunity for seeing noctilucent clouds continues as in June, however, towards the end of the month, particularly after midnight, some of the important late summer/early autumn constellations begin to be seen. 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.
Should you venture outside you will need a torch. Use a red light head torch if you have one, or put red plastic over a torch to illuminate the skymap and preserve your night vision which improves greatly over time. Wrap up warm and with a little perseverance, about 20 minutes, you will feast your eyes on the universe that you live within. Enjoy and indulge!
One prominent feature looking southeast in the summer sky is the Summer Triangle. This isosceles triangle is an asterism formed by the three bright stars Deneb, in the constellation of Cygnus, Vega, in the constellation of Lyra and Altair in the constellation of Aquilla the Eagle. The Summer Triangle is a most useful tool to have during June July and August and it continues to remain climbing higher in the sky through October, November and into December providing us with a marker or starting point for our stargazing. Meanwhile, our previous marker, the asterism, Spring Triangle comprised of Arcturus, Spica and Regulus have travelled further west leaving only Arcturus and Spica in the sky.
Scorpius, a distinct constellation, sits low on the southern horizon and skims across the mountain tops displaying its brightest star Antares which is well worth looking at through binoculars and seeing its deep red glow. An hour or so later, around midnight, Sagittarius will take the place of Scorpius and is recognisable by its distinctive shape, the asterism called the Teapot. At this time of night, it will appear with the spout to the right and slightly tipped. Ancient civilisations saw Sagittarius
as a horse and rider, but the Greeks saw it as a Centaur, half man – half horse wielding a bow and arrow, but for, me it is difficult to see beyond the teapot within the clouds of stars within the Milky Way.
Ursa Major, the great Bear, is home to many galaxies that can be seen with binoculars or better still through a small telescope. It is worth taking a closer look at the handle of the Plough which is also the middle star of the bear’s tail. Binoculars will reveal that Mizar is a binary star and its close neighbour Alcor is also seen as a binary star. Each of the companion stars are also binary’s making a close sextuplet system of stars that are bound together by gravity.
Cygnus, the Swan, looks magnificent at this time of year positioned high in the eastern sky flying over Cephus and Lacerta which in turn are over Cassiopeia.
Capella, the brightest star in Auriga, the Charioteer in both Greek and Chinese mythology, can be seen low on the horizon with much of the constellation too low to see at this time of year.
July sees increased meteor activity. The positioning is not good for the Capricornids which are active between the 3rd July and 14th August peaking on July 30th. The rate is around 5 meteors per hour, but they can produce spectacular fireballs. The parent body for this shower is Comet 169P/NEAT.
A more prominent shower will be the Delta Aquarids which are active from 13th July to 24th August peaking on July 30th at 25 meteors per hour. The parent body for this shower is Comet 96P/Machholz.
The Perseid shower takes place between 17th July and 24th August peaking on 12/13th August at 80 meteors per hour. The parent body is Comet 109P Swift-Tuttle.
Mercury reached its greatest elongation west on 4th July. After this time, it starts to descend back towards the east until it vanishes from view at the end of the month. Attempting to view Mercury is not recommended unless specialist equipment is available as it remains close to the Sun.
Venus approaches a feint Mars on the 13th with both planets 28 degrees from the Sun and low in the sky. On the 21st Venus remains in the constellation of Leo and is less than one degree from its brightest star, Regulus.
Earth arrives at aphelion on 5th marking its most distant point from the sun. This year the aphelion distance is 1.107au or 152,100,000km.
Mars leaves the constellation of Cancer for Leo on the 10th and joined by Venus on 13th with the two planets just half a degree apart. This month marks the 45th anniversary of the landing of Viking 1, the first successful landing on the planet.
Jupiter can be found shinning brightly in the constellation of Aquarius. The planet rises in the early hours of the morning and remains in sight until dawn breaks.
Saturn remains visible in the evening sky but is low to the southern horizon.
Uranus can be found less than 2 degrees from the waning crescent Moon on 4th in the constellation of Aries. The planet rises before midnight and is difficult to see in the twilight conditions that prevail at this time of year.
Neptune currently in retrograde in the constellation of Aquarius. A small telescope is required to view it.
Nights of particular 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.
1st July Moon last quarter, morning sky.
3rd July Capricornid meteor shower begins, runs until 14th August.
4th July Uranus 2.1 degrees north of the Moon at 15.25 hours.
5th July Moon at apogee, 405,341km, at 14.47 hours.
5th July Earth at aphelion, 152,100,527km from the Sun, at 22.27 hours.
8th July Mercury 3.8 degrees south of the Moon, at 04.38 hours.
10th July New Moon, not visible.
13th July Venus appears directly over Mars in the west 22.00hours . This can be seen with the naked eye but is much better with a pair of binoculars.
13th July Aquarids meteor shower begins until 24th August The peak is 28-30th July.
16th July Perseid meteor shower begins until the 23rd August. The peak is on 12/13th August.
17th July Moon first quarter, evening sky.
24th July Full Moon, visible all night24th July Jupiter 4 degrees east of the Full Moon with Saturn directly above the Moon low southeast in the constellations of Aquarius and Capricornus, 23.30hours.
30th July Alpha Capricornids peak, less than 5 per hour. Look out for slow yellow fireballs.
30th July Delta Aquarids peak, 20 per hour. The sun will be setting around 21.30 hours and the sky will not be dark enough until around 23.00 hours. Best chance of viewing will be just before midnight on 28th in Aquarius next to rising Jupiter 10 – 15 degrees above the southeast horizon.
31st July Moon last quarter, morning sky.