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.


August 2017

Mercury

Mercury

Mercury may be glimpsed low down in the West after sunset at the beginning of the month.

The planet passes through inferior conjunction on 26th.

Venus

Venus

Venus is a brilliant morning object rising three hours before the Sun throughout the month. The planet is visible among the stars of Gemini moving into Cancer on 25th.

On 25th Venus will be in a straight line with the twin stars of Gemini.

On 19th the crescent Moon will be visible below Venus.

Mars

Mars

Mars remains too close to the Sun to be seen this month.

Jupiter

Jupiter

Jupiter is a brilliant evening planet among the stars of Virgo above that constellation's brightest star, Spica.

At the beginning of August the planet sets around two hours after the Sun but by the end of the month the planet becomes lost in the evening twilight.

Jupiter is close to the Moon on 25th.

Saturn

Saturn

Saturn is an evening object low in the South after sunset and setting around 1:30am at the beginning of the month.

The planet is among the stars of Ophiuchus, a constellation ignored by astrologers. This places Saturn well South of the equator this year so the pale yellow, star-like planet does not rise very high from UK latitudes.

Look for the planet below the Moon on 3rd.

Through a telescope the magnificent rings are easy to see and this year they are at an open angle. If you have access to a telescope, use the Moon to locate Saturn and look at it through a telescope on a clear night. The sight of the rings is one of the best views in the sky. During 2017, we are looking down onto the planet's North Pole so the rings appear to be wide open. The rings are open wide every fifteen years.

By the end of August, Saturn will be settting around 11pm.

Sun

The Sun

The Sun continues to move south which causes the days to get shorter, now at a gathering pace. On 1st August the length of day is 15 hours 23 minutes. This decreases to 13 hours 37 minutes by the end of the month, a decrease of nearly two hours.

During August the time of midday (when the Sun is due South and at its highest in the sky) is just after 13:00 (remember the clocks went forward in March) until the final day of the month.

The Sun begins the month in Cancer and enters Leo on 10th.

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-Aug
05:24
13:06
20:48
15h 23m
56.4°
 
02-Aug
05:25
13:06
20:46
15h 20m
56.1°
 
03-Aug
05:27
13:06
20:44
15h 17m
55.9°
Moon close to Saturn
04-Aug
05:28
13:06
20:43
15h 14m
55.6°
 
05-Aug
05:30
13:06
20:41
15h 10m
55.3°
 
06-Aug
05:32
13:06
20:39
15h 07m
55.1°
 
07-Aug
05:33
13:06
20:37
15h 04m
54.8°
Full Moon at 18:11 - Partial Lunar Eclipse (not UK)
08-Aug
05:35
13:06
20:36
15h 00m
54.5°
15 hour day
09-Aug
05:36
13:05
20:34
14h 57m
54.2°
 
10-Aug
05:38
13:05
20:32
14h 54m
53.9°
Sun "enters" Leo
11-Aug
05:39
13:05
20:30
14h 50m
53.6°
 
12-Aug
05:41
13:05
20:28
14h 47m
53.3°
Perseid Meteor Shower Maximum
13-Aug
05:42
13:05
20:26
14h 43m
53.0°
 
14-Aug
05:44
13:05
20:24
14h 40m
52.7°
 
15-Aug
05:46
13:04
20:22
14h 36m
52.4°
Morning Half Moon
16-Aug
05:47
13:04
20:20
14h 32m
52.1°
 
17-Aug
05:49
13:04
20:18
14h 29m
51.8°
 
18-Aug
05:50
13:04
20:16
14h 25m
51.4°
 
19-Aug
05:52
13:04
20:14
14h 21m
51.1°
Moon close to Venus
20-Aug
05:54
13:03
20:12
14h 18m
50.8°
 
21-Aug
05:55
13:03
20:10
14h 14m
50.5°
New Moon at 18:30 - Total Eclipse of the Sun (Partial in UK)
22-Aug
05:57
13:03
20:08
14h 10m
50.1°
 
23-Aug
05:58
13:03
20:06
14h 07m
49.8°
 
24-Aug
06:00
13:02
20:04
14h 03m
49.4°
 
25-Aug
06:02
13:02
20:01
13h 59m
49.1°
Moon close to Jupiter - 14 hour day
26-Aug
06:03
13:02
19:59
13h 56m
48.7°
 
27-Aug
06:05
13:01
19:57
13h 52m
48.4°
 
28-Aug
06:06
13:01
19:55
13h 48m
48.0°
 
29-Aug
06:08
13:01
19:53
13h 44m
47.7°
Evening Half Moon
30-Aug
06:10
13:01
19:50
13h 40m
47.3°
 
31-Aug
06:11
13:00
19:48
13h 37m
47.0°
 

Moon

The Moon

The Moon will be close to Saturn on 3rd.

The Moon will be close to Venus on 19th.

The Moon will be close to Jupiter on 25th.

Meteor Shower

The Perseid meteor shower reaches its peak on the night of the 12th-13th. This year the Gibbous Moon will be visible and this will blot out the fainer meteors.

Look towards the North East towards midnight for a few days on either side of this date.

Shooting stars should be visible for a few days on either side of the maximum date. The best nights for UK observers will be the night of 12th-13th.

Look between the zenith (overhead point) and the North East after 22:00 and wrap up well. At its best this annual shower should provide about one shooting star per minute.

Moon

Partial Eclipse of the Moon

A Partial Eclipse of the Moon occurs on 7th.

The eclipse is entirely visible in the Central Asia, India, Pakistan, East Africa, Madagascar, most of Australia, South East Asia and Antarctica.

No part of this eclipse will be visible from the UK.

The eclipse will last for just under two hours and at maximum 25% of the Moon will be in the Earth's shadow.

Sun

Total Solar Eclipse

On 21st, a Total Eclipse of the Sun occurs.

From the UK, a small partial eclipse will be visible at sunset.

Event Time
(London Time - BST)
Eclipse Begins 19:40
Mid-Eclipse (4%) 20:04
Sunset 20:10

The path of totality of a total solar eclipse is a long narrow strip, never more than a few hundred km wide. The spectacular effects of totality are only visible within this region. The Moon's dark shadow (or umbra) covers only a small percentage of the Earth's surface.

Outside the path of totality, a partial eclipse is visible. Partial eclipses are less interesting, with far less to see. Even if the Sun is 99% covered by the Moon, the spectacular phenomena of totality will not be seen and special filters or glasses MUST be used to look at it.

On 21 August 2017, the next total eclipse of the Sun will take place.

This shows the eclipse details projected onto a globe of the Earth. The path of totality is the shown by the dark blue lines. A partial eclipse is visible where there are turquoise and red lines. The Moon's shadow moves from left to right. The red asterisk along the path of totality shows the location of the longest duration.

For this eclipse, the Moon's shadow (umbra) touches down on the Earth at 16:48 GMT (which is 5:48pm London Time - this is daylight saving time) in the Pacific Ocean south of Alaska. At this point the width of the shadow will be 62km and the duration of totality will be 0m 52s and the eclipse will be total at local sunrise.

The shadow then moves eastwards across the sea for 28 minutes travelling at just under 7km per second when it touches Earth and slowing down as the Earth bulges up to meet it. It reaches dry land in the North Western USA at 17:16 when it will be travelling at 1.2km per second. On the coast the path width will be 99km and the duration of totality will be 1m 59s. Here the eclipse will be total at mid-morning.

The shadow then crosses several states of the USA including Oregon, Idaho and Wyoming.

In Casper (where we will be based), the path width will be 110km (67 miles), the shadow speed under 800m per second (1700 miles per hour) and the duration 2m 26s. Totality occurs around 11:45am local time.

The umbra continues through Nebraska, the Kansas - Missouri border and into a small part of Illinois.

The small town of Carbondale is close to the place of maximum duration (2m 40s) and the widest shadow path (115km) moving at 650 m per second. The local time of totality will be around 1:20pm in this region.

Totality is longest here because this is the part of the Earth closest to the moon during the eclipse (remember the Earth is a sphere). The umbra is its widest and is moving at its slowest relative to the spinning Earth - this gives more shadow taking longer to pass.

Carbondale has a second claim to fame. It is also within the path of totality of another total eclipse in April 2024. This small town will see two total eclipses of the Sun in seven years. The average wait for two total eclipses of the Sun in one place is about 400 years. London, gets no total solar eclipse between 1715 and 2151.

The umbra then continues through Kentucky, Tennessee, Georgia and South Carolina. It leaves North America at 18:48 travelling at 670 m per second with a path width of 114km and a duration of 2m 34s. The eclipse is now occurring in the afternoon (local time).

The umbra spends the next 75 minutes moving over the Atlantic Ocean. There are no major landfalls during this period. No doubt, ships will position themselves to see the eclipse at sea.

The umbra finally leaves the Earth at 20:02 (GMT) in the ocean south of the Cape Verde Islands. The duration of totality is now 0m 47s and the path width has shrunk to 57km (as these regions at the edge of the Earth are further from the moon) with the eclipse occurring at local sunset. The shadow sweeps off the Earth travelling at more than 4km per second.

The umbra will have been in contact with the Earth for 3 hours 13 minutes marking out a narrow band with a length of 13,900km and a maximum width of 115km. Totality will have been visible over an area covering 0.26% of the Earth's surface, a tiny amount.

The smallness of the area where totality is visible is what makes these eclipses so rare. Although total eclipses are frequent for the Earth as a whole, totality occurs in a single location roughly every four hundred years on average. As I have stated before, in London the last Total Eclipse of the Sun occurred on 3 May 1715 and the next will not be seen until 14 June 2151. If we look at a larger area, like the UK, total solar eclipses are more common. Even so, the last two eclipses were in 1927 and 1999 and the next will be in 2090.

On either side of the path of totality, a partial eclipse will be visible. The lighter partial shadow (or penumbra) is much wider than the dark umbra. A partial eclipse will be seen over all of North America, all of Central America and the northern part of South America, parts of Eastern Siberia, Western Africa, Iceland, Greenland and the extreme West of Europe. The closer a location is to the path of totality, the larger the partial eclipse will be.

21 August 2017 will be the first total eclipse of the Sun since 9 March 2016. The next one occurs on 2 July 2019.

All maps copyright Fred Espenak, Xavier Jubier.


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

Saturn in the evening. Venus, Mercury and Mars in the morning. Equinox.


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.