Monthly Skywatchers' Page

For London and the UK

Sun And Nine Planets
The Sun and eight major planets (plus KBO Pluto) to scale. Earth is third planet from the left.


Introduction

The location of the stars and constellations can be learnt throughout a single year from books, mobile phone applications or planetarium software. Each month of the year, the same stars are visible from a given location. Different stars and constellations are visible as the year progresses. For example, in London, the constellation of Orion is always visible in the evenings of winter months of January and February. Scorpius is visible in the summer months of June and July around midnight.

The planets resemble stars except that, generally, they do not twinkle. Unlike the stars whose patterns are fixed, planets wander through the sky changing their positions amongst the starry background. This means that their periods of visibility change as the relative position of the Earth, Sun and planet vary. In one year Mars may be visible in August at midnight. In another year it may be behind the Sun and invisible from Earth during August.

This page gives the details of visibility for the five naked eye planets: Mercury, Venus, Mars, Jupiter and Saturn. It also gives information about comets, meteor showers and non-regular phenomena like eclipses, transits and occultations.

The Observers' Glossary explains the terms used. Alternatively run the mouse cursor over terms in maroon.


The descriptions below are for viewers in the Northern Hemisphere, especially London and the United Kingdom.
The planetary information is valid for any location at the same or similar Latitude (51.5°N).
Note that a degree in the sky is twice the apparent diameter of the Moon.

All times on this page are London (UK) times. This is normally GMT (Greenwich Mean Time also known as Universal Time).
In the United Kingdom, the clocks go forward by one hour for British Summer Time (BST) between mid March and late October.
A 24 hour clock is used so that 7pm is written 19:00.


December 2018

Mercury

Mercury

Mercury makes its final morning appearance of 2018 this month becoming visible after the first few days of the month.

The planet can be found low in the South East, rising around 6:15am. Look for it after 6:50am when it will be clear of the horizon but the sky will still be reasonably dark.

On 5th the very thin crescent Moon will be above Mercury and below the more brilliant Venus.

The planet resembles a silvery white star and is brighter than most stars.

After the middle of the month, Mercury is joined by Jupiter, itself emerging from the morning twilight. The two planets will be seen close together in the pre-dawn sky on 21st and 22nd, Jupiter the brighter of the pair.

By the end of the month Mercury will disappear into the morning twilight.

Venus

Venus

Venus is a brilliant morning object rising over four hours before the Sun among the stars of Virgo.

The planet is at its greatest brilliancy at the beginning of December when it will shine 16 times brighter than Sirius, the brightest star.

Look for Venus on the mornings of the 3rd and 4th as the crescent Moon will form a stunning pairing with the planet (and again on 1st and 2nd of January).

Venus begins the month to the left of the blue star Spica, the brightest of Virgo, but moves away during December. The planet's rapid motion carries it into Libra on 14th.

This month will see Venus at its best for this morning apparition in Northern latitudes.

Mars

Mars

Mars continues as an evening object shining with its distinctive red colour in the South after it gets dark. The planet continues fading and begins the month in Aquarius.

As in November, Mars continues moving Northwards, getting higher in the sky as the month progresses. This causes the planet to continue setting around 11:30pm throughout December.

The rapid motion of Mars moves it into Pisces on 22nd.

The Moon will be close to the planet on 14th and 15th.

At the end of the month, Mars will still be visible in the South in the early evening but will be noticeably higher and fainter than at the beginning of December.

On 7th observers with a telescope will be able to see Mars very close to the distant planet Neptune.

Jupiter

Jupiter

Jupiter appears in the morning sky around the middle of the month when it can be found close to Mercury and below Venus.

Saturn

Saturn

Saturn is now too close to the Sun to be visible.

Sun

The Sun

Since June the Sun has been moving southwards causing the days to get shorter.

This continues until 22:22 on 21 December, the shortest day of the year in the Northern Hemisphere. This is the time of the Winter Solstice. On this day the Sun will be above the horizon for less than 7 hours 50 minutes, less than 30 percent of the 24 hours of a calendar day.

On the shortest day the Sun at noon will be only 15 degrees above the horizon as seen from London. Compare this to 62 degrees in June. The Sun is barely getting above the trees at this time of year. The low Sun and the few hours of daylight are the reasons the days are cold at this time of year.

The time of midday (when the Sun is due South and at its highest) begins December at 11:49. During the month, the time of midday moves forward reaching 12:00 on 24th and 25th. On these days, Sun Time is equal to Clock Time. This only happens four times a year. By the end of the month midday will be occurring at 12:03.

The fact that the time of midday is moving forward during the month has two effects. The shortest day is on 21st but the earliest sunset (15:51) is on 13th, eight days earlier. Also the latest sunrise (08:06) is at the end of December. This happens because the times of sunrise and sunset are almost stationary relative to the time of midday because we have reached the shortest day. The movement of midday forward is dragging these times forward with it.

The Sun begins the month in Ophiuchus, the "serpent bearer", a constellation ignored by astrologers.

The Sun enters Sagittarius on 18th.

Note that the astronomical Zodiac dates (the actual Zodiac dates) do not tie in with astrology as astrologers are using dates from two thousand years ago.

Date Sunrise Midday Sunset Length of Day Sun's Noon Altitude Notes
28-Nov
07:39
11:48
15:57
08h 17m
17.2°
 
29-Nov
07:40
11:48
15:56
08h 15m
17.0°
 
30-Nov
07:42
11:49
15:55
08h 13m
16.9°
Morning Half Moon
01-Dec
07:43
11:49
15:55
08h 11m
16.7°
Venus at Greatest Brilliancy
02-Dec
07:45
11:49
15:54
08h 09m
16.6°
 
03-Dec
07:46
11:50
15:53
08h 07m
16.4°
Moon close to Venus
04-Dec
07:47
11:50
15:53
08h 05m
16.3°
Moon close to Venus
05-Dec
07:48
11:51
15:52
08h 03m
16.2°
Moon close to Mercury
06-Dec
07:50
11:51
15:52
08h 02m
16.0°
 
07-Dec
07:51
11:51
15:52
08h 00m
15.9°
New Moon at 07:20
08-Dec
07:52
11:52
15:51
07h 59m
15.8°
 
09-Dec
07:53
11:52
15:51
07h 57m
15.7°
 
10-Dec
07:54
11:53
15:51
07h 56m
15.6°
 
11-Dec
07:55
11:53
15:51
07h 55m
15.5°
 
12-Dec
07:56
11:54
15:51
07h 54m
15.5°
 
13-Dec
07:57
11:54
15:51
07h 53m
15.4°
Earliest sunset
14-Dec
07:58
11:55
15:51
07h 52m
15.3°
Moon close to Mars
15-Dec
07:59
11:55
15:51
07h 51m
15.3°
Evening Half Moon - Moon close to Mars
16-Dec
08:00
11:56
15:51
07h 51m
15.2°
8am sunrise
17-Dec
08:01
11:56
15:51
07h 50m
15.2°
 
18-Dec
08:01
11:57
15:52
07h 50m
15.2°
 
19-Dec
08:02
11:57
15:52
07h 50m
15.1°
 
20-Dec
08:03
11:58
15:52
07h 49m 50s
15.1°
 
21-Dec
08:03
11:58
15:53
07h 49m 44s
15.1°
Solstice at 22:22 - shortest day - Mercury close to Jupiter
22-Dec
08:04
11:59
15:53
07h 49m 44s
15.1°
Full Moon at 17:49 in Orion - Mercury close to Jupiter
23-Dec
08:04
11:59
15:54
07h 49m 51s
15.1°
 
24-Dec
08:05
12:00
15:55
07h 50m
15.1°
Midday at 12 Noon
25-Dec
08:05
12:00
15:55
07h 50m
15.2°
 
26-Dec
08:05
12:01
15:56
07h 50m
15.2°
 
27-Dec
08:05
12:01
15:57
07h 51m
15.2°
 
28-Dec
08:06
12:02
15:58
07h 52m
15.3°
 
29-Dec
08:06
12:02
15:58
07h 52m
15.3°
Morning Half Moon
30-Dec
08:06
12:02
15:59
07h 53m
15.4°
 
31-Dec
08:06
12:03
16:00
07h 54m
15.5°
Latest sunrise - 4pm sunset
01-Jan
08:06
12:03
16:01
07h 55m
15.5°
Moon close to Venus
02-Jan
08:06
12:04
16:02
07h 56m
15.6°
Moon close to Venus

Moon

The Moon

The Moon will be close to Venus on 3rd.

The Moon will be close to Venus on 4th.

The Moon will be close to Mercury on 5th.

The Moon will be close to Mars on 14th.

The Moon will be close to Mars on 15th.


It is easy to depend on astronomy or CMMS software to perform daily computational activities and to keep track of data. Astronomy enthusiasts can choose from a wide variety of software options, while facility managers may have fewer options if they require CMMS software for their business.


Next Month

Mars in the evening. Venus and Jupiter in the morning. Perihelion. Total Eclipse of the Moon.


All times on this page are London (UK) times.

Sources: Astronomy Now magazine, Cybersky, Starry Night Pro, USA Naval Observatory and UK Nautical Almanac Office.

© 2018 KryssTal
All sky images by Starry Night Pro Plus 6
Eclipse predictions (maps) courtesy of Fred Espenak, NASA's GSFC


Books From Amazon.co.uk


Observers' Glossary

An explanation of the terms used by sky observers. Includes descriptions of how the objects of the solar system behave in the sky as seen from Earth (especially the Northern Hemisphere high latitudes).


KryssTal Related Pages

Tables and data about the Sun, Earth, Moon, planets, asteroids and comets. All terms used are explained.

An account of how various properties of stars can be measured by studying starlight. Includes brightness, distance, luminosity, temperature, mass, radius, density and an introduction to the H-R Diagram.

A table containing a list of the 20 brightest stars in the Earth's sky. Explanations of all the associated terms like magnitude, spectral type and radial velocity.

A detailed account about eclipses, transits and occultations. These are irregular phenomena that can be observed in the sky. Includes eclipse trips around the world with photos and well as photos of recent transists of Mercury and Venus.

An easy-to-understand scaling of the Universe in space. Distances in space are represented by the time light takes to travel there.

An easy-to-understand scaling of the Universe in time. The chronology of the Universe is compared to a real year.

How humanity came from believing Creation Myths to postulating the Inflationary Big Bang Theory. The key stages in our understanding of our place in the cosmos and the people who broadened our understanding.

What do we mean by the words day, week, month, year? Who invented our calendar? When did the third millennium begin? The relation between time and astronomy.

The force that moves apples and planets. A short introduction to the ideas of Kepler and Newton that culminated with the theory of Universal Gravitation.

A look at the mathematics of a sphere with a section on sundials and the equation of time.


External Skywatching Links

These links will open in a separate window

StarDate Online
An excellent online skywatchers' magazine featuring detailed monthly information about astronomical events.

Astronomy Picture of the Day
A different image each day with an extensive archive and explanations.

Society for Popular Astronomy
Monthly planet and star gazing details with maps for young people.

Telescope House
A London based source of astronomical equipment, telescopes, software, maps and books.

Southern Sky Watch
Sky watchers information for the southern hemisphere.

Starry Night Pro
Superb planetarium software. Simulate the sky from anywhere on the Earth and any time.