Night Sky Notes – October 2017

Night sky notes for October 2017                 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. Comet 2017 01 ASSINI moves northward through the constellations of Taurus and Perseus as a binocular object, reaching perihelion (October 14th), its closes point to the Sun in its orbit, visible in our eastern early evening skies by mid October. (see notes)

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.

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 . 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.

Uranus in the constellation of Pisces 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. Venus may be glimpsed in dawn twilight with Mars, conjunction October 5th.

In the east mid evening the seven sisters’ (Pleiades, M45) star cluster and constellation Taurus heralds the autumn skies. It is worth noting just what difference the change to GMT (UT) on Sunday 30th October makes on the night skies at the end of the month. 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 Orionid meteor showers, parent comet periodic Comet 1P / Halley, have low rates peaking late October.

Planets in October 2017

Mercury is poorly placed in October with superior conjunction on October 8th

Venus shines brightly low in morning twilight skies; the phase 95%. Conjunction with Mars Oct 5th

Mars is visible very low in the south/ south west in the constellation Leo s in pre dawn skies

Jupiter is now in our daytime skies with conjunction on Oct 26th

Saturn is a evening twilight object in early October and has conjunction with the Sun in mid December

Uranus is visible mid evening in the constellation of Pisces. (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 2017

New Moon         Oct 19th       Moonless, best time for deep sky observing and Comets

First Quarter     Oct 27th      Best days to see shadow details in lunar craters (early evening)

Full Moon          Oct 5th          Best days to see bright ray craters like Copernicus / Tycho.

Last Quarter     Oct 12th       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 29th 2017.

GMT is the same as UT (Universal Time, Greenwich Mean Time beginning at midnight)

Meteor showers

Orionids range October 16th to 30th, maxima 21st to 23rd – Fast meteors with persistent trails, quite favourable.

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 (no activity listed for 2017)

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 2017 O1 ASSINI a binocular object in the early evening eastern aspect in the constellation of Perseus
  • Waxing crescent Moon visibility    . Caution. Do NOT look at the Sun directly with or without optical aid. A thin 1% waxing crescent moon is visible from 15 minutes after sunset on October 20th to moonset at 6:43 pm BST. Note the dimly lit part visible by Earthshine is readily seen with binoculars or small telescope October 21st and 22nd. Only look for the crescent Moon after the sun has completely set.



Sky looking south 8.30 pm BST in early October 2017

Oct - South

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

Binoculars show the Milky Way, the dark rift through Cygnus and the rich star field down through the constellation of Scutum and to the south west horizon – best seen from a dark observing site on moon less evenings.

Oct - Neptune Finder

More detailed sky notes and LAS Newsletters , Finder charts are available to LAS members via the Members` page on the LAS Website

Sky looking east at 8.30 pm BST early October 2017

Oct - East

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.

Oct - Uranus

Sky looking north at 8.30 pm BST early October 2017

Oct - North

Follow the pointer’s Dubhe and Merek to find the polestar Polaris

Sky looking southwest at 6.50 pm BST early October 2017

Oct - South West

The summer constellations slip westward into evening twilight.

Additional   notes   Finder chart for binocular / telescopic comet 2017 O1 ASSINI – Visible low in the east in late evening – best observed in moonless conditions from a dark sky site – Refer to for updates .

Oct - Comet 01 Assini

More detailed finder charts and newsletters are available to LAS members on the member’s page