Night Sky Notes – December 2017

Night sky notes for December 2017            Geoff Mitchell

The December night sky now sees the late autumn constellations prominent early evening and now heralds some familiar winter constellations. The late autumn / winter night sky contains many fine objects to view with both binocular and small telescopes.

The constellations of Cygnus and Lyra can be seen slipping into the west early evening; these are noted for the bright stars of Deneb and Vega. The Milky Way stretches from the constellation of Auriga , marked by the bright star Capella in the east up into Perseus and through the `W` shaped constellation of Cassiopeia high overhead and down along the cross shaped constellation of Cygnus low in the west . This faint band of stars best seen on dark moonless evenings

Auriga has the bright star Capella, which is circumpolar from UK latitudes and so is always visible. The constellation of Auriga contains some nice star fields and open star clusters visible in binoculars, notably M36, M37 and M38

High In the south 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 early evening mid month. Another fine globular cluster is M15 in the constellation, best seen telescopically.

In the north Ursa Major or The Great Bear, known for The Plough asterism is seen low with its handle 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 currently marking a position close to the north celestial pole.( useful when polar aligning your equatorial telescope mount )

Uranus in the constellation of Pisces is visible early evening and 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 is notable due to the blue colour, telescopes show a tiny disc rather than the sharp pinpoints of stars in the field of view.

Look to the east mid evening to see the seven sisters’ (Pleiades, M45) star cluster and constellation Taurus which heralds the autumn skies. The Hyades star cluster makes the characteristic `V` shaped asterism in the constellation of Taurus and is noted for the bright, red foreground star Aldebaren in Arabic Al Dabaran is `The follower ` of the Pleiades across the skies `, in old English colloquially known as `the eye of the bull`.

By late evening the familiar winter constellations of Orion (The Hunter) with bright red star Betelgeuse (top left) , white star Rigel (bottom right ) and the three stars of Orion’s belt Mintaka , Alnilam and Alnitak . Below Orion’s belt can be seen the misty patch that is M42 / M43, visible to the unaided eye, it is one of the gem’s of the winter skies when seen with a telescope. This nebula some 30 light years across is illuminated by a group of four hot young stars that is known as the `Trapezium `asterism, visible under moderate magnification.

The full (perigee) Moon conditions around Dec 3rd make the Geminid meteor shower peak very favourable around December 14th in moonless conditions late evening. The Ursid meteor shower peaking around Dec 23rd has favourable condition until moon rise (after midnight).

Telescopic comet 2016 R2 Panstarrs heads northward from Orion during December but at around 11th magnitude is faint and likely to be difficult to observe visually in larger telescopes even in moonless dark skies.



Planets in December 2017

Mercury is our morning twilight skies from mid month with greatest elongation on Jan 1st 2018.

Venus is poorly placed in dawn skies early in the month before heading into our daytime skies.

Mars is an early morning object in December rising at around 3am and currently presents a tiny disc telescopically.

Jupiter rises by 4am in the constellation of Libra low in our eastern early morning skies..

Saturn is in our daytime skies with conjunction on December 21st, emerging into dawn twilight around New Year.

Uranus is an evening object in the constellation of Pisces; the planet shows a tiny blue disc telescopically.

Neptune is poorly placed low in evening skies setting around 9pm.

Moons phases in December 2017

New Moon         Dec 18th                Moonless, best time for deep sky and comet observing.

First Quarter     Dec 26th               Best days to see shadow details in lunar craters (early evening)

Full Moon          Dec 3rd                 Best days to see bright ray craters like Copernicus / Tycho.

Last Quarter     Dec 10th                Moon visible in daytime skies. Do not look directly at the Sun.

Winter solstice Dec 21st (16:29 GMT) – Shortest day

Meteor showers

Geminid range December 8th to 17th, maxima 14th December – ZHR 100 /hr slow, bright meteors very favourable.

Ursid range December 17th to 25th maxima Dec 23rd – low rates ZHR just 10/ hour – favourable.

The highlights of the month.

December skies, Milky Way visible high overhead on moonless evenings in darker skies.

M31 the Andromeda Galaxy is visible on moonless evenings, best seen in binoculars.

Double cluster, on the Perseus / Cassiopeia border, nice pair of star clusters.

Pleiades (Seven Sister’s) star cluster (M45) rising in the east best seen with binoculars.

Orion Nebula (M42) is a beautiful sight seen telescopically.

Crescent Moon visibility, a 1.8 % waxing crescent moon is visible in twilight in the south west from around 20 minutes after sunset (from 4.10 pm) with moonset by 5:14 pm on December 19th

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

Sky looking south 7pm in mid December

Dec - 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. See finder maps for Uranus and Neptune.


Sky looking east at 7pm mid December

Dec - East

The constellations of Taurus, Auriga, Gemini and Orion can be seen rising mid evening in December.


The Seven Sister’s cluster (M45, Pleiades) is an easily identified star cluster. Some people with keen eyesight may see up to 13 stars, but a telescope will show over 400 faint stars in the cluster.

Sky looking north at 7pm mid December

Dec - North

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

Sky looking west at 6pm mid December2017

Dec - West

The summer triangle asterism of Altair, Deneb and Vega slip westward

LAS general finder chart for Uranus for Nov / Dec 2017


Uranus now past opposition is around 5.7 magnitude positioned in the south early evening, visible in binoculars or small telescope as a blue coloured star like point near Zeta Piscium. Use the Circlet or Square of Pegasus to star hop to the field of view. [Position RA 01h 32m, Dec +09° 57m.

General finder map   Neptune


RA 22h 53m , Dec -8° 2` , Mag 7.9   Neptune is close to Lambda Aquarii