December 2017

Welcome to SkyEye, your guide to this month's celestial events.

The Calendar

Date Event
Friday 1
Saturday 2 Moonlight disrupts observations of the Phoenicid meteor shower.
Sunday 3 Moon occults first magnitude star Aldebaran: visible from central and eastern Asia and northwestern North America, and beginning around 11:30 UT.
Neptune at east quadrature
Full Moon
Monday 4 Moon at perigee just 17 hours after reaching full phase
Tuesday 5
Wednesday 6
Thursday 7 The waning gibbous Moon ruins any chance of seeing the poorly-studied Puppid-Velid meteor shower.
Friday 8 Moon occults first magnitude star Regulus: visible from most of Europe and northern Asia, and beginning around 21:20 UT.
Saturday 9
Sunday 10 Last Quarter Moon
Monday 11
Tuesday 12
Wednesday 13 Mercury at inferior conjunction
Thursday 14 The waning crescent Moon does not unduly affect observations of the ever-reliable Geminid meteor shower. The maximum is predicted to occur at 06:30 UT.
Friday 15
Saturday 16
Sunday 17
Monday 18 New Moon
Tuesday 19 Moon at the farthest apogee of the year
Wednesday 20
Thursday 21 Earth at solstice: the word solstice means 'sun stands still' so that on this day, the solar declination reaches an extreme. In this case, the Sun appears directly over the Tropic of Capricorn in the southern hemisphere. From now until the solstice in June, days will be getting shorter in the southern hemisphere and longer in the northern hemisphere.
Saturn at conjunction
Friday 22 The waxing crescent Moon leaves the evening skies dark to see the Ursid meteor shower. Maximum activity occurs around 15:00 UT.
Saturday 23
Sunday 24
Monday 25
Tuesday 26 First Quarter Moon
Wednesday 27
Thursday 28
Friday 29
Saturday 30 Moon occults first magnitude star Aldebaran: visible from eastern North America, Greenland, Iceland, northern Europe and western Asia, and beginning around 23:00 UT.
Sunday 31

The Solar System

The word planet is derived from the Greek word for 'wanderer'. Unlike the background stars, planets seem to move around the sky, keeping mostly to a narrow track called the ecliptic, the path of the Sun across the stars. Dwarf planets and small solar-system bodies, including comets, are not so constrained, often moving far above or below the ecliptic.

Sun OphiuchusSagittarius

Although Ophiuchus is not a member of the zodiac, the ecliptic passes through it.

Mercury Ophiuchus

The closest planet to the Sun disappears from western skies early in the month as it heads towards conjunction on 13 December. It reappears in the east before sunrise late in the month, rising rapidly for southern hemisphere viewers and becoming quite high above the horizon.

Venus LibraScorpiusOphiuchusSagittarius

The morning star is very low in the east, rising not long before the Sun.

Mars VirgoLibra

The red planet rises ever earlier in the morning, approaching the brighter planet Jupiter in the sky.

Jupiter Libra

Like its neighbour Mars, Jupiter spends the month drawing away from the Sun in the morning sky and brightening slightly as it does.

Saturn Sagittarius

The ringed planet is soon lost to view this month as it undergoes solar conjunction on 21 December. It reappears next year in the morning sky.

Uranus Pisces

This faint planet, the most distant object in the solar system visible to the naked eye, sets around midnight.

Neptune Aquarius

A small telescope is necessary to view the most distant planet in the solar system but you will need to look for it in the early evening as it sets well before midnight. It is at east quadrature on 3 December.

The Celestial Sphere

Constellations are patterns of stars in the sky. The International Astronomical Union recognises 88 different constellations. The brightest stars as seen from the Earth are easy to spot but do you know their proper names? With a set of binoculars you can look for fainter objects such as nebulae and galaxies and star clusters or some of the closest stars to the Sun.

Descriptions of the sky for observers in both the northern and southern hemispheres are available for the following times this month. Subtract one hour from your local time if summer (daylight savings) time is in effect.

Local Time Northern Hemisphere Southern Hemisphere
1730 hours (1830 hours summer time) 45° N 30° S
1930 hours (2030 hours summer time) 45° N 30° S
2130 hours (2230 hours summer time) 45° N 30° S
2330 hours (0030 hours summer time) 45° N 30° S
0130 hours (0230 hours summer time) 45° N 30° S
0330 hours (0430 hours summer time) 45° N 30° S
0530 hours (0630 hours summer time) 45° N 30° S