The summer months have been particularly uneventful, or more so the events have been hard to spot in the bright summer nights but the month of August has some amazing celestial treats in store for both the weathered and the fresh stargazer.
One of the most beautiful and mesmerizing shooting stars will return around 12 August, the famous Perseid meteor shower will grace our skies with its dominant presence.These small specks of dust, roughly the size of a grain of sand originate from the largest known object to ever have visited the Earth’s orbit, the comet 109P/Swift-Tuttle, which has a massive diameter of 26 km!The last time this parent comet passed Earth was the early 90’s which resulted in a very active meteor shower in the summer sky peaking at around 200 per hour.But Swift-Tuttle will not grace our presence again until 2126 with an orbit cycle of 130 years so we have to make do with the remnants of its debris, the small meteoroids and particles that broke off from the big ball of dust, ice, rock and gas that is the comets nucleus to follow in their parent’s path!Needless to say the show is still spectacular, as long as we are graced with clear skies.
These particles interact with our atmosphere and burn up before reaching the ground creating brilliant streaks of light in the sky last a few seconds.If you watch closely you may notice a green hue at the tail of the streak that can linger for up to 10 seconds, this is caused by ionised oxygen atoms that can only happen with very fast meteoroids like the Perseids, which can reach speeds of up to 210,000 km/h.That’s like running from Armagh to Dublin in roughly 2.5 seconds!Now to find these astronomical sprinters you need to find where they originate from in the sky, or the radiant.The Perseids naturally emanate from the celestial hero Perseus mid-high in the north-east sky.It should hopefully have a ZHR or Zenithal Hourly Rate of about 90 meteors per hour but that’s with a nice dark, clear sky.Try your best to find an area with as little light pollution as possible, have a camping trip and stay in the countryside.The peak time to watch the stars for the Perseids in late on the 11th/12th August or early evening on the 12th/13th August but keep your eyes peeled for dates surrounding this as you could spot a sporadic Perseid zipping across the sky.
One of the main issues when it come to a successful meteor shower viewing, other than weather and light pollution is that nosey Moon.Unfortunately it will be a waning crescent Moon around the 12th and still quite bright but don’t expect it in the sky until about 1 am BST when it will rise in the north east alongside Jupiter in the constellation of Taurus.Try you best to avoid looking in this direction of the sky for the best chance to glimpse to Perseids.
Since we will be searching the sky for meteors it would make sense to gaze deeper at the background of these celestial fireworks because this area of the sky has a lot to offer.Although Perseus had a brief mention in July’s night sky, we can take a deeper look into the mythical hero in August.Its brightest star is Miphak with an apparent magnitude of 1.75.It marks the torso of the hero, although it is translated to meaning elbow but, nonetheless, it is a very interesting star to focus on.Mirphak is one of the massive white supergiant stars with a huge mass about eight times that of our Sun and it is blindingly bright, shining with the energy of nearly 5000 Suns!It is the first evolved star of a group of hot white and blue stars, due to its huge mass it is the first of these stellar siblings to evolve into a Supergiant while the rest are still in their main life sequence of burning Hydrogen.If you can get your hands on a pair of binoculars or a telescope you will see that this supergiant is framed by a beautiful field of white and blue stars, definitely worth a look.
Located above Perseus himself, right from where the Perseids radiate from, we have a very interesting object worth attention, the well-known “Double Cluster” which is literally a stunning sight through binoculars or a small telescope.It can be seen by the naked eye but the sight is a bit less breath taking with them looking like a pair of fuzzy stars in the sky.They both have their own stellar designations, NGC 884 or Chi Persei and NGC 869 or H Persei.They appear right next to each other in the sky but they are actually different distances from each so they are not bound by gravity but that does not necessarily mean they have no connection.They are both believed to have originated from a group of star clusters with a similar age known as the Perseus OBI Association.Although they both originate here they do vary in age with NCG 869 being older at 19 million years and NCG 869 being the tender age of just 12.5 million years old, relatively babies compared to our 4.6 billion year old Sun.The stars located within these clusters are a mixed bag of main sequence blue and white stars and larger red and orange giant stars that are nearing the end of their relatively short stellar existence.
If we make our way back to Mirphak and move further on below it until we reach the second brightest star in Perseus, Algol.Now located between Algol and to the right constellation of Andromeda we have a very interesting object well worth spotting.It is the open cluster Messier 34.It is much older than the Double Cluster at 180 million years old, but still not near the age of our Sun.This beautiful cluster contains about 80 stars, 20 of which are very bright and visible through binoculars or a small telescope.You will know if you’ve led eyes on stellar beauty as it has the impressive ‘X’factor!Now it won’t belt out a pop tune for you but it does form an impressive ‘X’ shape in the sky and these stars have drifted across the sky to take up an impressive 5 light years of sky.
Moving on from these deep sky objects we can look at how the planets are moving this month.Both Mercury and Venus are early sky objects this month with Mercury getting brighter as the month goes on.It will rise in the north east in the constellation of Cancer the Crab and on 18 August at around 04:00 UT with a magnitude of 1.4 and by 31 August it will rise and hour before sunrise with an impressive magnitude of -1.3. Venus is also very bright this month and rises roughly the same time as Mercury in the east in the constellation of Gemini with an apparent magnitude of -4.2!
Now for all you Moonwatchers out there, August is bursting with lunar loveliness as we are being treated to two full Moons.Normally there are 3 full moons in each season and the Maine Farmer’s Almanac has them categorised as the ‘early, ‘mid’ and ‘late’ Moons.But occasionally a fourth full Moon creeps in and to save the naming of the ‘late’ Moon they referred to the 3rd as a ‘blue’ moon.But another astronomical publication in later years misinterpreted this and called the fourth moon the ‘blue’ moon and this in turn lead to a radio show in the 1980’s doing the same which can lead to some confusion but meaning in popular culture today, this sneaky fourth Moon being referred to as the ‘Blue’ Moon.The first full Moon fell on 2 August and the ‘Blue’ Moon is on 31 August but remember do not search the sky for an aqua blue moon unless you want to add a bit of festivity to your star gazing and put a blue filter on your telescope!
We are nearing the end of summer and although that means kids go back to school and the onset of chillier weather, it does mean darker skies so perhaps less late night and early morning stargazing.But August is providing us with a fantastic end to the summer so fingers crossed we have clear skies for the welcomed return of the celestial fireworks, the Perseids!