Night sky notes for October 2018 Geoff Mitchell
The October night sky now sees the autumn constellations prominent early evening and heralds some familiar winter constellations rising by late evening and contains many fine objects to view with both binocular and small telescopes. Short period Comet 46P Giacobini- Zinner continues to move southward through the constellations of Monoceros and Canis Major. The comet should be visible as a faint `smudge` at around 8.5m magnitude in small telescopes / binoculars (see notes) but in our midnight skies. It is worth noting just what difference the change to GMT (UT) on Sunday 28th October makes on the night skies at the end of the month.
The constellations of Cygnus, Lyra and Aquila can be seen slipping westward early evening; these are noted for the bright stars of Deneb, Vega and Altair respectively forming the `Summer Triangle ` asterism.
The Milky Way stretches from Perseus rising in the east, through the `W` shaped constellation of Cassiopeia high in the north east and along the cross shaped constellation of Cygnus. This faint band of stars best seen on dark moonless evenings continues down through the obscure constellation of Scutum and on in the direction of the centre of the Milky Way (not visible from the UK) low on the horizon. Over head the particularly rich star fields running through Cygnus show the spiral arm of our galaxy and some of the obscuring dust in the form of the dark banding of the Cygnus Rift – Binoculars show these star fields well. Cygnus also contains a beautiful yellow / blue double star, Albireo (β Cygnii) visible in binoculars / small telescopes [60mm OG, X 25 magnification]
Auriga has the bright star Capella and can be seen low in the north east early evening, Capella is circumpolar from UK latitudes and so is always visible. In the east the constellation of Pegasus, noted for its `Square ` shape and the adjacent constellation of Andromeda noted for The Andromeda Galaxy (M31) , visible to the unaided eye as a faint fuzzy patch on moonless evening can now be seen mid evening . Also in Andromeda the blue /orange coloured double star Almach (γ Andromedae) visible telescopically [60mm OG, X 35 magnification]
The Square of Pegasus is a useful sign post constellation and also is a good test for sky conditions, (how many faint stars you see within the square is indicates just how good your seeing conditions are). Follow the two end stars (Scheat and Markab) down to find the star Fomalhaut in the constellation of Pisces Australis (The Southern Fishes), visible very low on the southern horizon late evening at the end of the month. Another fine globular cluster is M15 in the constellation, best seen telescopically.
In the North West, Ursa Major, The Plough (asterism) or The Great Bear is seen low with its handle or tail parallel to the horizon mid evening. Use the right hand pair of stars Dubhe and Merak (The pointers ) to find the faint pole star Polaris and hence the position of North . Follow the curve of Ursa Major’s tail to the orange star Arcturus in the constellation Bootes (The Herdsman) low in the west. To the east of Bootes find the `horse shoe ` shaped constellation of Corona Borealis (Northern Crown) and the `Keystone asterism ` in the constellation of Hercules also noted for the globular cluster M13 containing around 750,000 stars, a good view with modest telescopes. Also in the constellation of Hercules is M92 another striking telescopic globular cluster.
Uranus in the constellation of Pisces and reaches opposition on October 24th and Neptune in the constellation of Aquarius are now both evening objects that can be located using binoculars and a suitable finder chart. A good starting point is to locate the Square of Pegasus and the ring of stars below the Square known as the `Circlet` in the constellation of Pisces (The Fishes), then star hop using the finder chart. Uranus and Neptune are notable due to the blue and green colour, Telescopes show a tiny disc rather than the sharp pinpoints of stars in the field of view. Saturn sets in twilight by late October, Mars shines brightly low in south western skies early evening.
In the east mid evening the seven sisters’ (Pleiades, M45) star cluster and constellation Taurus heralds the autumn skies. The Hyades star cluster makes the characteristic `V` shaped asterism in the constellation of Taurus and noted for the bright, red foreground star Aldebaren , which now rises by early evening.
The recent close approach of parent comet Giacobini-Zinner 21P may give rise to increased activity of the Draconid Meteor shower , peak around October 8th in favourable moonless conditions [ 20 to 50 per hour ?]
Short period Comet 46P Wirtanen brightens during October poorly place from UK low in early morning skies but will be better placed in November / December reaching naked eye visibility in evening skies.
Planets in October 2018
Mercury is poorly placed in October emerging into evening twilight
Venus is poorly placed, too close to Sun in evening twilight; Inferior conjunction is on October 26th.
Mars is unmistakable, orange and bright (-1.3m) but very low in the south/ south west in the constellation of Capricornus. Telescopes show a disk but the low elevation from the UK results in poor quality views
Jupiter is visible low in evening twilight, setting by 18.30 BST – poorly placed.
Saturn is an early evening twilight object in the constellation of Sagittarius low in the south west in October.
Uranus is visible mid evening in the constellation of Aries. (Binocular / Telescope required). See notes.
Neptune in Aquarius visible early evening (Binocular / Telescope required). The constellation of Aquarius is positioned low in the south east by mid evening. (See notes)
Moons phases in October 2018
New Moon Oct 9th Moonless, best time for deep sky observing and Comets .
First Quarter Oct 16th Best days to see shadow details in lunar craters (early evening)
Full Moon Oct 24th Best days to see bright ray craters like Copernicus / Tycho.
Last Quarter Oct 2nd/31st Moon visible in daytime skies. Do not look directly at the Sun.
Note – Clocks change to GMT (i.e. go back 1 hour), Sunday October 28th 2018.
GMT is the same as UT (Universal Time, Greenwich Mean Time beginning at midnight)
Meteor shower s
Orionids range October 16th to 30th, maxima 21st to 23rd – Fast meteors with persistent trails, unfavourable
Taurids range October 20th to November 30th – Maxima Nov 5th /12th slow meteors, some bright events. Unfavourable –moonlight interferes.
Draconids maxima October 9th, parent comet Giacobini- Zinner, period 6.6 years favourable (increased activity? )
The highlights of the month .
October skies, Milky Way visible high over head on moonless evenings in darker skies.
Uranus and Neptune, binocular objects to find using suitable finder charts (see notes)
M31 the Andromeda Galaxy is visible on moonless evenings, best seen in binoculars, low magnification.
Double cluster, on the Perseus /Cassiopeia border, nice pair of star clusters, binocular, medium magnification.
Albireo, the star Beta Cygnii is a nice blue/ yellow double star seen telescopically, moderate magnification.
Comet 21P Giacobini-Zinner within 6 degrees of bright star Sirius October 12th (early morning)
Waxing crescent Moon visibility . Caution. Do NOT look at the Sun directly with or without optical aid.
A thin 0.6% waxing crescent moon is visible from 15 minutes after sunset on October 9th to moonset at 7 pm BST.
Note the dimly lit part visible by Earthshine is readily seen with binoculars or small telescope October 10th and 11th in evening twilight Only look for the crescent Moon after the sun has completely set.
Sky looking south 8.30 pm BST in early October 2018
Follow the stars Scheat and Merkab in the square of Pegasus down to find the star Fomalhaut in the constellation of the `Southern Fishes ` Pisces Australis. Planet Neptune is located in the constellation of Aquarius – see LAS finder chart below
More detailed sky notes and LAS Newsletters , Finder charts are available to LAS members via the Members` page on the LAS Website www.lutonastrolink.org.uk
Sky looking east at 8.30 pm BST early October 2018
M45 (Seven Sister’s) star cluster a familiar sight in autumn skies
Use the corner stars of the Square of Pegasus to point (roughly) to Uranus and then use the finder charts and a pair of binoculars to find the `blue` coloured star that in fact is the planet Uranus.
Sky looking north at 8.30 pm BST early October 2018
Follow the pointer’s Dubhe and Merek to find the polestar Polaris
Sky looking west 8.30 pm BST in early October 2018
The familiar summer constellations head towards the evening twilight. Arcturus is easily spotted due to its orange colour . Saturn low in the south west can be seen early evening .
Additional notes Finder chart for binocular / telescopic short period comet 21P Giacobini Zinner.
Visible low in the east but in the early morning – best observed in moonless conditions from a dark sky site . The comet is located just 6 degrees (a binocular field east of the bright star Sirius around 12th October. [Magnitude 8.5m]
More detailed finder charts and newsletters are available to LAS members on the member’s page