BrightStar Astronomy Night Sky Guide December 2017 - header image

Welcome to our December Night Sky Guide – the final one for 2017!

Are you confused about constellations or confounded by conjunctions? Perhaps just puzzled trying to pinpoint the position of the planets?

No problem! Here’s this month’s guide to “what’s up” in the night sky.

While this night sky guide is written for southern hemisphere amateur astronomers, much of the content is still relevant for those in the northern hemisphere – the precise time and location in the sky may vary to those noted, though.

Observing Highlights

  • 14th  – Geminids meteor shower
  • 22nd – Solstice


Mercury starts this month in the western, evening sky, but over the coming days will rapidly drop back towards inferior conjunction  (i.e. Mercury’s orbit puts it between the Earth and the Sun). It will emerge from the Sun’s glare in late December, when it can be found rising before the Sun in the eastern sky. **

Venus, like Mercury, spends December too close to the Sun for safe observation. Unlike the smaller planet, Venus is approaching superior conjunction, which will place it behind the Sun on the far side of the solar system **

Mars rises in the early morning during December, where it can be found first in the constellation of Virgo, and later Libra as the month progresses. Towards the end of the month, it will begin to noticeably close the gap with Jupiter, and the pair will be separated by less than one degree early next year.

Jupiter rises early in the pre-dawn sky for much of December, rising earlier as the month progresses. On the 14th and 15th, it will be joined by Mars and the crescent Moon.**

Saturn is still placed on the far side of our solar system and will be in conjunction with the Sun on the 22nd of this month. This rules out any chance of safe observations during December.

Uranus can still be found high in the northern sky (southern, if you happen to live in the northern hemisphere) this month. It can be found in the constellation of Pisces, close to its borders with Aries and Cetus.

Neptune is located in the constellation of Aquarius during December and will sink below the western sky before midnight. The best time to observe this distant planet is around the New Moon, which occurs on the 18th of this month.

** Observations close to the Sun should not be attempted by inexperienced observers! Instant and permanent blindness can occur as a result of small errors. For maximum safety, the Sun should be obscured by a structure or by the ground.

The Moon

Full Moon

December 4th .svg

Last Quarter

December 11th

New Moon

December 18th*

First Quarter

December 26th


December 19th

406,603 km


December 4th

357,492 km

 * The best time for viewing the Milky Way, Nebulae, Galaxies, and other faint objects is around this date


  • 3rd    –  Aldebaran 0.8° from the Moon
  • 6th    –  Saturn 1.4° from Mercury
  • 14th  –  Jupiter 4° from Moon
  • 14th  –  Mars 4° from Moon
  • 24th  –  Neptune 1.4° from Moon
  • 25th  –  Jupiter 0.8° from Alpha 1 Librae


Bright Comets




C/2017 T1 (Heinze)Hydra, Cancer~9th
(3200) Phaethon (2018)See Link~10th


Meteor Showers


Thought to arise from the object 3200 Phaethon (which also happens to be visible this month), the Geminids are one of only two regular meteor showers thought to arise from an asteroid, rather than a comet.

They are one of the most reliable showers in recent years, with hourly rates regularly exceeding 100 meteors per hour.

This year, conditions are excellent for viewing the Geminids, as the peak is predicted to occur on the 14th – only a few days before the new Moon on the 18th of December.


The constellation of Aries - Constellation lines, constellation art, and location.


The Ram“: Aries is one of the 12 constellations that comprise the zodiac, and is located between Taurus and Pisces. In Greek mythology, it represents the ram with the golden fleece.

Brightest Star: Hamal (Alpha Arietis)

Eridanus constellation - constellation art, constellation lines and location.


The River Eridanus“: Eridanus is home to a region of space almost one billion light-years across that contains very few galaxies and is known as the Eridanus Supervoid.

Brightest Star: Achenar (Alpha Eridani)

The constellation of Fornax - constellation art, constellation lines and location


The Furnace“: Partly ringed by the constellation of Eridanus, Fornax is home to some of the most distant galaxies ever photographed, as it was the location chosen for the Hubble Ultra-Deep Field image.

Brightest Star: Alpha Fornacis

The constellation of Horologium - constellation lines, constellation art and location in the sky


The Pendulum Clock“: Horologium is one of thirteen southern constellations that were named after scientific instruments of the enlightenment by Nicolas Louis de Lacaille in the mid-1700s.

Brightest Star: Alpha Horologii

The constellation of Hydrus - constellation art, constellation lines, and location in the sky


The Male Water Snake“: First established by Dutch astronomer Petrus Plancius in 1598, this small, southern constellation became known as Hydrus, meaning “The male water snake”, to distinguish it from the much larger constellation of Hydra, which refers to the female.

Brightest Star: Beta Hydri

The constellation of Perseus - constellation lines, constellation art, and location in the night sky


Perseus“: Known since antiquity, the constellation of Perseus represents the Greek hero of the same name that slew Medusa, a Gorgon that could turn all that gazed upon her to stone – a fact that is often depicted in the constellation art.

Brightest Star: Mirfak (Alpha Persei)

The constellation of Triangulum - constellation art, constellation lines, and location in the night sky


The Triangle“: Triangulum is a small constellation in the northern sky. It is home to the Triangulum Galaxy(M33), which is one of the closest large spiral galaxies to our own Milky Way.

Brightest Star: Beta Trianguli