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.


April 2018

Mercury

Mercury

Mercury is too close to the Sun to be visible this month.

-

Venus

Venus

Venus is visible in the West as a brilliant evening object, six times brighter than the brightest star. The planet begins the month setting two hours after the Sun but this period increases to two and a half hours by the end of April.

The planet is moving among the stars of Aries passing into Taurus on 19th.

The Moon will be close to Venus on 17th.

Venus passes close to the bright star cluster, the Pleiades (Seven Sisters) on 24th. By the end of April, the planet will be close to the star, Aldebaran (the eye of the bull) and the v-shaped cluster, the Hyades.

Venus and the Moon
Looking West at 8:45pm on 17th.
The brilliant Venus can be seen above the crescent Moon.
The v-shaped star cluster (Hyades) with the star Aldebaran
and the compact Pleiades (Seven Sisters) can be seen above the planet.

Mars

Mars

Mars rises before 2am during April.

The planet begins the month among the stars of Sagittarius close to and to the right of yellow Saturn.

The faster moving Mars passes below Saturn on 3rd when the two planets will be a couple of moon-widths apart. After that date, Mars will be seen to the left of Saturn.

Mars continues to brighten noticeably during the month. At the beginning of April the planet is the same brightness as Saturn but by the end of the month it will be twice as bright.

On 7th Mars and Saturn can be seen just below and to the left of the Moon.

Mars, Moon and Saturn
Looking South at 5am on 7th.
Yellow Saturn is to the left of the Moon. Red Mars is to the left of Saturn.

Jupiter

Jupiter

Jupiter is now visible for much of the night among the stars of Libra.

The planet rises around 10pm at the beginning of April and just after 8pm by the end of the month. It is brighter than any star but not as brilliant as Venus.

The planet is close to the Moon on 3rd and 4th and again on 30th.

Through a small telescope, the planet's four large moons can easily be seen.

Saturn

Saturn

Saturn rises after midnight among the stars of Sagittarius close to Mars.

Look for the yellow star-like planet on the 7th when it will be close to the Moon, with Mars to its left.

During 2018, Saturn will be low in the sky as it is now at its furthest south in its 30 year cycle.

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 2018, 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.

Sun

The Sun

Following the Spring Equinox in March, the Sun continues to move Northwards during April. This causes the days to get longer. At the beginning of the month the day is 12 hours 57 minutes long. By the end of April the day length is 14 hours 47 minutes, an increase of 1 hour 50 minutes.

The time of sunset begins the month at 19:33 and ends the month at 20:21, nearly an hour later.

At the beginning of the month the time of midday is 13:04 (remember the clocks are one hour ahead now). By the end of April the time of midday has drifted back to 12:57. The time of midday is at 13:00 for five days around the 14th. On these dates sun time (as measured by a sundial) agrees with clock time. This only happens four times a year.

The Sun begins the month in Pisces and enters Aries on 18th.

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
29-Mar
06:43
13:05
19:28
12h 45m
42.0°
 
30-Mar
06:40
13:04
19:30
12h 49m
42.4°
 
31-Mar
06:38
13:04
19:31
12h 53m
42.8°
Full Moon at 12:37 (Virgo)
01-Apr
06:36
13:04
19:33
12h 57m
43.1°
 
02-Apr
06:33
13:04
19:35
13h 01m
43.5°
13 hour day
03-Apr
06:31
13:03
19:36
13h 05m
43.9°
Mars close to Saturn - Moon close to Jupiter
04-Apr
06:29
13:03
19:38
13h 09m
44.3°
Moon close to Jupiter
05-Apr
06:27
13:03
19:40
13h 13m
44.7°
 
06-Apr
06:24
13:02
19:41
13h 16m
45.0°
 
07-Apr
06:22
13:02
19:43
13h 20m
45.4°
Moon close to Mars and Saturn
08-Apr
06:20
13:02
19:45
13h 24m
45.8°
Morning Half Moon
09-Apr
06:18
13:02
19:46
13h 28m
46.2°
 
10-Apr
06:16
13:01
19:48
13h 32m
46.5°
 
11-Apr
06:13
13:01
19:50
13h 36m
46.9°
 
12-Apr
06:11
13:01
19:51
13h 40m
47.3°
 
13-Apr
06:09
13:01
19:53
13h 44m
47.6°
 
14-Apr
06:07
13:00
19:55
13h 48m
48.0°
Midday at 13:00
15-Apr
06:05
13:00
19:57
13h 51m
48.4°
 
16-Apr
06:03
13:00
19:58
13h 55m
48.7°
New Moon at 01:57
17-Apr
06:00
13:00
20:00
13h 59m
49.1°
Moon close to Venus - 8pm sunset
18-Apr
05:58
12:59
20:02
14h 03m
49.4°
14 hour day
19-Apr
05:56
12:59
20:03
14h 07m
49.8°
 
20-Apr
05:54
12:59
20:05
14h 10m
50.1°
 
21-Apr
05:52
12:59
20:07
14h 14m
50.4°
 
22-Apr
05:50
12:59
20:08
14h 18m
50.8°
Evening Half Moon
23-Apr
05:48
12:58
20:10
14h 21m
51.1°
 
24-Apr
05:46
12:58
20:12
14h 25m
51.4°
Venus close to the Pleiades (Seven Sisters) star cluster
25-Apr
05:44
12:58
20:13
14h 29m
51.8°
 
26-Apr
05:42
12:58
20:15
14h 32m
52.1°
 
27-Apr
05:40
12:58
20:17
14h 36m
52.4°
 
28-Apr
05:38
12:57
20:18
14h 40m
52.7°
 
29-Apr
05:36
12:57
20:20
14h 43m
53.0°
 
30-Apr
05:34
12:57
20:21
14h 47m
53.3°
Full Moon at 00:58 (Libra) - Moon close to Jupiter

Moon

The Moon

The Moon will be close to Jupiter on 3rd.

The Moon will be close to Mars on 7th.

The Moon will be close to Saturn on 7th.

The Moon will be close to Venus on 17th.


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

Jupiter visible all night long. Mars and Saturn in the morning. Venus in the evening.


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.