Of the bright naked eye planets on show only Jupiter and Mars are readily visible.
Conspicuous Jupiter rises around midnight and is located below the ‘twins’ in Gemini over in the east.
Always worth observing with any telescope, look in particular for the dark banding on the disk and the Galilean moons. On the morning of the 26th, Jupiter lies nearby a waning moon.
Mars rises a few hours after Jupiter, passing above Regulus, the chief star in the ‘sickle’ of Leo around mid-October. Mars has an obvious orange hue, but as yet shows no detail when observed through all but the largest of scopes. The Moon joins Mars and Regulus on the 29th and 30th.
The Celestial Ocean – The ‘Winged Signpost’
The autumn night sky contains several ‘signpost’ stellar patterns.
One of these, currently well placed high to the south by mid evening, is known as the ‘Square of Pegasus’, part of the constellation of Pegasus itself.
Pegasus is often depicted as the winged steed of Perseus, which sprang forth from the blood of the gorgon Medusa after Perseus had decapitated her.
However in mythology Pegasus was actually ridden by another hero, Bellerophon, who was sent on a mission to kill the Chimaera, a fire-breathing monster, part lion, part snake, and part goat.
The stars forming the ‘square’ are not particularly brilliant, but do encompass a seemingly sparse area of sky and therefore appear relatively conspicuous.
Starting from the top left hand star, Alpheratz, travelling clockwise around the ‘square’ we in turn encounter Scheat, Markab and Algenib.
Alpheratz is actually the chief star of Andromeda, the body of which extends away to the east.
It is the jumping off point to locate our sister galaxy, the Andromeda galaxy. At a distance of 2.65 million light years the Andromeda galaxy is considered the most remote object visible to the unaided eye if skies are dark and transparent. It is astonishing to reflect that this faint smudge of light emanates from over 300 billion suns arranged in a spiral system spanning some 160,000 light years across.
Projecting a line diagonally from Alpheratz down through Markab (alpha Pegasi), you will be guided to a zig-zag asterism of stars representing the ‘water jar’, part of the constellation of Aquarius, the Water Bearer. According to one legend this group represents Zeus pouring down the waters of life from heaven. Several stars in Aquarius have names beginning with ‘Sad’ which in Arabic means ‘luck’ (sa’d ).
Let’s now track down Fomalhaut, the most southerly 1st magnitude star to rise over Britain.
Conveniently, the two right hand stars in the ‘square’ point down to it just above the S horizon. Fomalhaut marks the mouth of Pisces Austrinus, the Southern Fish, into which the waters of Aquarius pour. At a distance of 25 light years, Fomalhaut has at least one planet orbiting around it.
The southern fishes’ northern counterpart – Pisces, occupies a large portion of the sky below Pegasus and Andromeda but is devoid of any notable stars.
According to Greco–Roman mythology Pisces was associated with Aphrodite and her son Heros who in order to escape from the monster Typhon jumped into the Nile, turning themselves into fish.
From minnows to whales, or a sea monster to be more precise, as we seek Cetus, in legend said to represent the gargantuan Cracken.
Although large, the stars of Cetus are mostly quite faint. Alpheratz and Algenib may be used to locate the whale’s brightest member, Diphda, which marks the tail of the creature.
The head, an irregular loop of faint stars highlighted by Alpha Ceti or Menkar, lies below Aries. The most celebrated object in Cetus is a variable star called Mira “the wonderful”, an extraordinary pulsating red super giant star over 250 million miles in diameter. When at maximum, a period lasting some 10 days, the deep orange hue of Mira is visible to the naked eye and can rival Menkar. Mira’s slow decline to minimum then takes seven months by which time even binoculars struggle to pick it out.
The whole period takes 332 days. Scheat and Algenib point down in Mira’s general direction so try and spot ‘wonderful Mira’ in the coming weeks.
A Celestial Halloween – Part 1
As we approach that time of year associated with All Hallows eve or Halloween and the fearsome witches Sabbath or Black Sabbat, the ghoulish and macabre is not surprisingly manifest amongst the constellations of the autumn night sky.
We shall begin in Perseus, who’s outline is well placed high to ENE, below the ‘W’ pattern of Cassiopeia.
Central to all the deeds of Perseus is the quest to kill the Gorgon; Medusa, a hideous creature with snakes for hair, a face covered with dragon scales complete with tusks and a gaze to die for; turning anyone instantly to stone.
Given this arduous task by King Polydectes, the gods secretly furnished Perseus with a polished bronze shield, a sword of diamond, a helmet of darkness and winged sandals. Useful items!
Perseus caught Medusa unawares by using her reflection in his shield before decapitating her with one stroke of his sword. On his homeward journey Perseus used the head to his good fortune, rescuing Princess Andromeda as she was about to sacrificed to the monstrous sea Craken, thereby winning her hand in marriage. Perseus later took his revenge on King Polydectes by turning him into a pillar of stone.
The constellation of Perseus partly lies within the rich Milky Way and is well worth exploring with optical aid of any type.
Its chief star is called Mirphak (or Mirfak), however, Beta Persei, or Algol is of far more interest.
In early antiquity it was noted with much consternation that this star appeared to ‘wink’ every third day. The star became known as ‘the demon’s head’ from the Arabic word ra’s al-ghul and on old star charts marks the decapitated head of Medusa. Today, the true nature of Algol is understood, an eclipsing binary, consisting of two stars orbiting close together, the fainter component passing directly in front of the primary every 2.9 days; the eclipse process or ‘wink’ lasting almost ten hours.
A twin cluster of stars known as the Double Cluster, an exquisite object when viewed at low magnification, marks the sword hand of Perseus. The cluster lies midway between Perseus and Cassiopeia.
Next time, the beautiful, but sinister Pleiades and news of perhaps a bright comet.
The next full meeting of Whitby and District Astronomical Socuety will be on November 5 at Whitby Community College, main block, room H1 from 7.30pm.
The next open nights at the Bruce observatory – Whitby college drive are on October 20 & 27 and November 3 & 10 from 7pm. All welcome.