Mars and Saturn just about remain on view, very low in the WSW evening twilight sky, becoming increasingly difficult to spot if your horizon is cluttered.
Saturn is lost by the end of the month, whilst Mars lingers, slowly sinking down toward the SW horizon.
Comet C/2013A1 Siding Spring, a binocular object, lies very close to Mars on the 19th (7.30pm).
The moon lies nearby Mars on the 28th and Saturn on the 25th.
Uranus comes to opposition on the 7th and hence is due south at midnight. N
eptune is visible in a telescope and lies near Sigma Aqr.Jupiter is a bright object in the dawn sky, moving into Leo by the month’s end. The moon is nearby on Oct 18th.
Mercury pops into the dawn sky during the final week of October and into November for its best morning apparition of the year. Look for it 30 minutes before sunrise (around 6am GMT) a few degrees above the east horizon.
Discovered in Jan 2013, comet Siding Spring is a comet from the Oort cloud, a giant swarm of debris chunks left over after the formation of the solar system which resides some 5000-100,000 AU from the Sun.
Containing up to 2 trillion chunks, this particular Oort fragment will pass exceptionally close to Mars on the 19th, skimming just 132,000 km above the red planet’s surface.
At mag +8.3 the comet should be an easy binocular target, though will be better seen in a short focal length scope just a few arc minutes from Mars. As astronomical twilight exists by 7.45pm look from 7.30pm, it will be a little bit of a challenge as Mars will only be five degrees above the SW horizon.
The Orionids (Oct 16-27) are the months most reliable shower, peaking on the 21st with hourly rates approaching 25.
Like May’s Eta Aquarids, Orionids are associated with Comet Halley, but are more favourable for northern hemisphere observers due to the radiant being situated high in the S by early morning hours. Orionids are swift, often producing persistent trains.
With the moon just a couple of days off New, this year offers up an excellent opportunity to catch some shooting stars - especially in the early dawn sky
The autumn night sky contains several ‘signpost’ stellar patterns which may be employed to locate various other constellations or stars. 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 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 and is the jumping off point to locate the Andromeda galaxy, our sister 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’.
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 almost directly 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 Menkar or Alpha Ceti, 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.
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 and looking only at her reflection in his shield, decapitated 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.
The first full Whitby and District Astronomical Society meeting of the new season will be on October 7 at Caedmon College, Normanby site (Whitby college as was) main block, room H1 from 7.30pm.
The next open nights at the Bruce observatory are on October 12 ,19 & 26 from 7pm.
Beginners/new members most welcome.
For more information email Mark at firstname.lastname@example.org, call 605516 or visit www.whitby-astronomers.com