Venus remains very low above the west horizon all month but as twilight shortens once again it becomes a little easier to spot.
The moon lies nearby on August 10. Saturn is also getting low, visible in the WSW for a few hours after sunset to the left of Spica, chief star in Virgo.
Through the eyepiece Saturn is still a fine spectacle with the rings favourably orientated. A scope will also reveal the most conspicuous of Saturn’s moons, Titan.
Our moon is nearby Saturn on the 12th. The dawn sky is home to Jupiter, Mars and Mercury. Look for them low in the ENE from 4:30am. Conspicuous Jupiter soon moves ahead of fainter Mars which is decidedly deep amber in hue. Mercury trails in their wake 3-5 degrees above the ENE horizon. By mid-month Mercury will have dropped down to the horizon, leaving Jupiter and Mars to pull away from the horizon haze.
Meteor Watch - The Perseids
One of the celestial highlights of the year, the Perseid meteor shower, peaks on August 12th and weather conditions permitting the prospect of spotting a few shooting stars over the Regatta weekend nights should be favourable.
The nights of 11th/12th or 12/13th will be the optimum time to view Perseids, but even 10/11th should not be ruled out. There will be little moonlight to interfere, the crescent moon will be setting in the late evening.
Zenith hourly rates (ZHR) for the Perseids are normally around 60-80 under ideal conditions, but actual observed rates are always substantially lower. Expect between 10-20per hour on the late evening of both the 11th and 12th, rising to 30-40 by the early morning hours.
In some regions of the world the Perseids are also known as “The Tears of St. Lawrence”, because the feast day of that saint falls on Aug 10th, just two days before the meteor peak. Laurentius, a Christian deacon, was said to have been martyred by being roasted alive on an iron outdoor stove by the Romans in 258 AD.
It was in the midst of this torture that Laurentius cried out: “I am already roasted on one side and if thou wouldst have me well cooked it is time to turn me on the other.”
Perseids are associated with the periodic comet Swift Tuttle which has deposited debris over many thousands of years. Each August Earth ploughs through this giving rise to the Perseids. This ‘debris’ is about the size of instant coffee granules, with the occasional pea or marble sized fragment. Typically these fragments ‘burn up’ at an altitude of around 60 miles having reached speeds of 39 - 45 miles per second. I have found over the years the most rewarding regions of the sky for spotting Perseids are high to the south-within the ‘Summer Triangle’ also around Ursa Major and the Square of Pegasus. As part of their Regatta events program, the Whitby and District Astronomical Society will be hosting a Perseid meteor party on the Archery green (opposite the skate park) West Cliff on both the 10th and 11th starting from 9pm.
‘Dark Nights’ Return.
Late August sees the resumption of astronomical twilight, the deepest level of ‘darkness’ experienced and amateur astronomers begin to turn their attention and telescopes toward all those deep sky objects previously masked in the summer twilight. With the majority of stars visible shortly after 10pm, the casual observer will also find it somewhat easier to identify constellation patterns. The most familiar of these; the saucepan outline of the ‘Plough’, which is part of Ursa Major – the Great Bear, can be located high in the NW. The curved ‘starry’ handle points down in the direction of Arcturus, brightest of our summer luminaries, situated at the foot of Bootes – the herdsman. Note the delicate starry circlet of Corona Borealis situated to the upper left of Arcturus. By utilizing the ‘pointer stars’ in the bowl of the Plough, one can pinpoint isolated Polaris, the pole star in Ursa Minor. The star often wrongly mistaken for the ‘North star’ at this time of year, Capella, scintillates low to the north in the circumpolar constellation of Auriga.
Much of the SW aspect of the sky is occupied by two large and sprawling constellations. The figure of Hercules, best identified by the ‘keystone’ asterism, stands upper left of Corona, whilst the vast, rather faint outline of Ophuichus – the Serpent Bearer extends down from Hercules towards the WSW horizon. Arcing just above the southern horizon, the stellar asterism known as the ‘Teapot’; the most distinctive part of Sagittarius may be traced if sky transparency is good. It is a pity that from UK latitudes the Archer is too far south to be fully appreciated, especially as this region contains many fine deep sky objects.
Much of the aquatically themed SE aspect is occupied by zodiac constellations, including Capricornus, the Sea Goat, Aquarius - the Water Bearer and Pisces the Fish. Dark skies are required to pick out the outlines of these less conspicuous constellations.
High overhead to the south and east reside three bright stars. Steely blue Vega in the small geometric pattern of Lyra is the most conspicuous, whilst to the east Deneb sits at the tail of Cygnus the swan. Pearly white Altair in Aquila the Eagle shines midway up in the South. These three stars are also known as the ‘summer triangle’ a term first used in the fifties by Sir Patrick Moore which has subsequently passed into popular usage. On the edge of the ‘triangle’ note the small arrow shape of Sagitta- the Arrow, together with the close-knit pattern of Delphinus - the Dolphin situated to its left. Sagitta certainly gives the impression of an arrow and with a little imagination, Delphinus does resemble the outline of a dolphin leaping out of water. Bizarrely Delphinus is sometimes known as ‘Jobs coffin’
Over in the NE the great hero Perseus begins to climb away from the horizon, whilst above, the familiar “W” pattern of Queen Cassiopeia holds court. Her daughter, Princess Andromeda, located to the lower right is marked by a chain of stars extending away from the winged horse Pegasus which occupies the mid regions of the E sky. Pegasus is best identified by ‘the great square’, an arrangement of four stars which enclose a sparsely populated area of sky. As the constellations associated with summer wing their way westwards, the appearance of the winged horse heralds the onset of a new season in the sky. Autumn approaches.
With darker skies returning, Whitby and District Astronomical Society will be hosting numerous star party events over the coming fortnight. First up is Regatta, where you will find us carrying out solar observations from the Sunken Garden, top of Spa drive, West Cliff on both the 10th & 11th, 2.30pm to 4.15pm.
Our evening regatta star parties (same dates) will commence at 9pm from the Archery green – Just across from the skate park, West Cliff.
Further public star parties will be held on August 17, 24, 25 and 31 from our usual location near Captain Cook’s statue. All from 9pm.