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.


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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.


January 2017

Mercury

Mercury

Mercury makes a brief appearance in the morning sky for about a week in the middle of January.

This is not a great apparition but, with a clear horizon, the planet may be glimpsed low above the South Eastern horizon about half an hour before sunrise.

Mercury will brighten during its brief apparition.

On 26th, the crescent Moon will be to the left of the planet but the two will be very close to the horizon.

Mercury and the Moon
Looking South East at 7am on 26th.
Mercury can be seen to the right of the thin crescent Moon.

Venus

Venus

Venus is a brilliant object visible in the South West after sunset. The planet sets more than four hours after sunset throughout January.

On 1st the thin crescent Moon will be visible to the right of Venus. On 2nd, the Moon will be closer to the planet and to its left.

Venus will dominate the evening sky throughout January and this will be the best time to see this brilliant planet, shining more than 14 times brighter than the brightest star.

On 12th Venus will be at greatest elongation. That means that the planet will be at its furthest away from the Sun as seen from Earth. After 12th, the planet will appear to move back in towards the Sun

The planet's rapid motion takes it through Aquarius and it passes into Pisces on 23rd.

During January, the brilliant Venus will be seen to approach the fainter but distinctly red-coloured Mars. On the last day of the month the two planets, just a few Moon widths apart, will be joined by the crescent Moon.

The Moon and Venus
Looking South West at 5:30pm on 2nd.
The brilliant Venus can be seen below the crescent Moon. The fainter Mars is above and to the left.

Mars

Mars

Mars is an evening object visible in the Southern skies among the stars of Aquarius setting around 9:30pm throughout the month.

On 19th the planet moves into Pisces and continues to fade slightly as it moves away from the Earth.

The planet continues to move Northwards and its motion against the background stars is apparent from night to night.

On 3rd the Moon will be seen close to Mars.

Throughout January the faster moving Venus moves closer to Mars. By the end of the month the two planets will be close together just a few Moon widths apart. On 31st, the pair are joined by the crescent Moon forming a spectacular view in the early evening sky.

The Moon with Venus and Mars
Looking South West at 5:45pm on 31st.
The Moon is below the brilliant Venus and the fainter Mars.

Jupiter

Jupiter

Jupiter continues to dominate the after-midnight sky rising at 1am at the beginning of January and before midnight by the end of the month.

The planet is in Virgo above that constellation's brightest star, Spica.

Jupiter is close to the Moon on 19th.

Jupiter and the Moon
Looking South East at 2am on 19th.
Brilliant Jupiter can be seen below the Moon.
The star, Spica, can be seen below the planet and Moon.

Saturn

Saturn

Saturn becomes visible in the morning sky after the middle of the month.

The planet will be rising in the South East among the stars of Ophiuchus. The planet will not be easy to find but it can be seen below the crescent Moon on 24th.

Sun

The Sun

After the Winter Solstice in late December, the days now begin to get longer in the Northern Hemisphere.

During January the length of the day in London increases from 7 hours 56 minutes to 9 hours 08 minutes, an increase of over an hour.

The time of midday (as measured by the Sun) begins the month at 12:04 but moves quickly forward to end the month at 12:14. This causes the slowly increasing daylight to be shunted into the afternoon.

For example on 14th, the Sun rises at 08:00 (giving exactly four hours of daylight before 12:00 Noon) and sets at 16:20 (giving 4 hours and 20 minutes of daylight after 12:00 Noon). From 1st to 15th, the time of sunrise changes from 08:06 to 07:59. This is a 7 minute change over two weeks. During the same period the time of sunset changes from 16:02 to 16:21, an increase of 19 minutes. During the first half of January, the evenings begin to get lighter while the mornings stay dark.

On 4th January at 14:17, the Earth will be at its closest to the Sun in its annual orbit. This is called Perihelion from the Greek for "near" and "Sun".

At perihelion, the Sun's distance from the Earth is 147.1 million km (as compared to 152.1 million km in early July). This is a difference of some 5 million km (or 3% of the total distance). The closer Sun gives the Northern Hemisphere winter 7% more heat than it would otherwise receive from the Sun. Also, the Earth is moving faster in its orbit around the Sun. This speed variation makes winter in the Northern Hemisphere 89 days long whereas the Northern Hemisphere summer lasts for 93 days. The speed variation is also one of the causes of the variable time of midday described above.

The Sun's distance from the Earth does not cause the seasons. These are caused by the Earth's axis being tilted at an angle of 23.5° to the plane of its orbit around the Sun. It is this that causes both the length of the day and the noon day altitude of the Sun to vary throughout the year. It also causes the seasons to be reversed in the Southern Hemisphere.

The Sun begins the month in Sagittarius and enters Capricornus on 19th. Note that the 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
01-Jan
08:06
12:04
16:02
07h 56m
15.6°
Moon close to Venus
Latest sunrise
02-Jan
08:06
12:05
16:03
07h 57m
15.7°
Moon close to Venus
03-Jan
08:06
12:05
16:05
07h 58m
15.8°
Moon close to Mars
04-Jan
08:06
12:06
16:06
08h 00m
15.9°
Perihelion at 14:17
8 hour day
05-Jan
08:05
12:06
16:07
08h 01m
16.0°
Evening Half Moon
06-Jan
08:05
12:06
16:08
08h 03m
16.1°
 
07-Jan
08:05
12:07
16:10
08h 05m
16.2°
 
08-Jan
08:04
12:07
16:11
08h 06m
16.4°
 
09-Jan
08:04
12:08
16:12
08h 08m
16.5°
 
10-Jan
08:03
12:08
16:14
08h 10m
16.7°
 
11-Jan
08:02
12:09
16:15
08h 12m
16.8°
 
12-Jan
08:02
12:09
16:17
08h 14m
17.0°
Full Moon at 11:34
Venus at Greatest Elongation
13-Jan
08:01
12:09
16:18
08h 17m
17.2°
 
14-Jan
08:00
12:10
16:20
08h 19m
17.3°
8am sunrise
15-Jan
07:59
12:10
16:21
08h 21m
17.5°
 
16-Jan
07:58
12:10
16:23
08h 24m
17.7°
 
17-Jan
07:58
12:11
16:24
08h 26m
17.9°
 
18-Jan
07:57
12:11
16:26
08h 29m
18.1°
 
19-Jan
07:56
12:11
16:28
08h 32m
18.3°
Morning Half Moon
Moon close to Jupiter
Sun "enters" Capricornus
20-Jan
07:54
12:12
16:29
08h 34m
18.5°
 
21-Jan
07:53
12:12
16:31
08h 37m
18.7°
 
22-Jan
07:52
12:12
16:33
08h 40m
19.0°
 
23-Jan
07:51
12:12
16:34
08h 43m
19.2°
 
24-Jan
07:50
12:13
16:36
08h 46m
19.5°
Moon close to Saturn
25-Jan
07:49
12:13
16:38
08h 49m
19.7°
 
26-Jan
07:47
12:13
16:40
08h 52m
19.9°
Moon close to Mercury
27-Jan
07:46
12:13
16:41
08h 55m
20.2°
 
28-Jan
07:44
12:13
16:43
08h 58m
20.5°
New Moon at 00:07
29-Jan
07:43
12:14
16:45
09h 01m
20.7°
9 hour day
30-Jan
07:42
12:14
16:47
09h 05m
21.0°
 
31-Jan
07:40
12:14
16:48
09h 08m
21.3°
Moon close to Venus and Mars

Moon

The Moon

The Moon will be close to Venus on 1st, 2nd and 31st.

The Moon will be close to Mars on 3rd and 31st.

The Moon will be close to Jupiter on 19th.

The Moon will be close to Saturn on 24th.

The Moon will be close to Mercury on 26th.

Vesta

Vesta, the brightest asteroid, reaches Opposition this month. Binoculars are needed to see it.

The asteroid is in Cancer.


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

Venus and Mars in the evening. Jupiter and Saturn in the morning. Annular Eclipse (not UK).


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.

© 2017 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.