The "Planet Clock" very useful tool to get familiar and orientated with the movements of the planets. It is not difficult to construct and need not cost anything.
Planet Clock Building Instructions
by Brian Keats
The stars spake once to Man.
It is world-destiny
That they are silent now.
To be aware of the silence
Can become pain for earthly Man.
But in the deepening silence
There grows and ripens
What Man speaks to the stars.
To be aware of the speaking
Can become strength for Spirit-Man.
Rudolf Steiner (1861-1925)
Aim: To make a circular clock face with a diameter of 30 cm. On this clock face will be drawn the 12 constellations of the Zodiac instead of the numbers 1 -12. The hands of the clock will be the planets, the hour hand being the Sun. N.B. This will be a manually driven 24 hour clock.
Considerations for choice of materials:
Somehow the hands of the clock have to stay in position on the clock face which will be standing vertically when finished. If you use fridge magnets for planets and the clock face is metal like a small 20 litre paint drum lid then this combination will work. You could also use felt for the face and planets as they will stick to each other. You could also use a pin-up board and pins for the planet.
Construction example (using drum lid and magnets):
i) Obtain a small drum lid and cut a circular piece of card that will fit neatly inside the drum lid i.e. the diameter of the card will be the same as the diameter of the drum lid without its rim. This card will be later pasted onto the lid.
ii) Using a compass draw a circle on the card such that there is a 5 cm margin (or a third of the radius of your card if it is a different size to the example) between it and the edge of the card (which is a bigger circle). In the drawing below the dotted portion would be 5 cm wide.
iii) In the dotted portion we now want to draw in the 12 constellations that the Sun, Moon and planets pass in front of each year. These 12 constellations constitute the Sidereal Zodiac where sider means star (Latin) and zodiac means animal circle (Latin). Note that their paths are constrained to a particular band of the sky. When you get to know these constellations it will be easier to find the planets. This zodiac does not have 12 equal divisions, each constellation is not the same size. In a later part of the course comparisons with and discussions of other zodiacs will be gone into. Most of them have 12 equal divisions. The zodiac we are using here is what you see in the sky when you look up. Some constellations are small and some big albeit we cannot actually see the divisions between them. There are differing opinions where these boundaries should be. Traditionally they were decided upon by the International Astronomical Union and it could be argued upon that they may not be correct. However it is helpful to have a yardstick with which to swap notes with others observing the sky. For this project the boundaries are going to be 30 degrees apart.
Using a protractor mark off 0, 30, 60, 90, 120,150,180,210,240,270,300,330 and back to 00 (same as 360) degrees.
The clockwise sequence is:-
Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpio, Sagittarius, Capricorn, Aquarius, Pisces.
See diagram below. When you have drawn this up you will have a clock face similar to the drawing below. Add the symbols next to each constellation.
Lightly colour Aries, Leo and Sagittarius Fiery colours like red;
and Gemini, Libra, Aquarius airy colours like yellow;
and Cancer, Scorpio, Pisces watery colours like blue;
and Taurus, Virgo and Capricorn earthy colours like brown.
The reason for the choice of the colours is that they correspond to the 4 elements Fire, Air, Water and Earth.
Planet Clock Sidereal Zodiac
Note 1] if you are making this clock in the northern hemisphere the zodiac sequence would be anticlockwise!
iv) Glue card onto the drum lid.
v) Drill a hole through the centre of the drum lid (and card) to fit a 6 mm bolt about which the drum lid can rotate.
vi) Make a stand on a base and attach the drum lid to the stand with the bolt.
Base and Stand
vii) Make a horizon profile (green in figure). This horizon profile also serves to block out that part of the Zodiac which would be below the horizon and therefore not visible. Half of the Zodiac is not visible at any one time.
viii) Make the planets by cutting out flexible magnetic strips that often used to adorn refrigerators
- Reading and Adjusting the Clock
i) Place the Sun magnet onto the clock in front of the relevant constellation. The current Sun position can be found by referring to calendars like the Antipodean Astro Calendar or one from an Astronomical Society, or from some newspapers that provide astronomical information. Please note that obtaining the Sun’s position from a horoscope would not be correct for this purpose. It would be 250 out and this will be dealt with in a later course.
ii) Do the same for the Moon and planets
iii) Rotate the clock so that the Sun magnet corresponds to the actual position of the Sun in the sky (or below the Earth if it is at night - remember it is a 24 hour clock). If for example the time is midday the Sun would be culminating (overhead) and so the clock can be rotated until it shows the Sun at the top of the clock. If it was midnight the Sun would be at the bottom (6 o'clock in a normal clock) but not visible as it would be behind the screen of the horizon profile you have built. In Fig 5 the Sun represents 4 pm as it is low down on the western side where the Sun sets.
- Reading the Clock
With the Sun magnet in the right position and the Moon in planets in front of the correct constellations we can have fun with the clock. Using the Fig 5 example we can see that at 4 pm Mercury, Sun, Venus, Pluto, Uranus and Saturn would be above the horizon. As the Sun is above the horizon we would not be able to see any of the planets at that time anyway. However we know that in a few hours time when the Sun is below the horizon it will be dark. If sunset was at six o’clock we could rotate the clock 300 anticlockwise (the sky, and all the planets with it, are moving from East to West 150 an hour). The Sun magnet would be in the same position as 9 o' clock in a normal clock. By then Sun and Mercury would be below the horizon. Uranus, Neptune and Pluto would still be above the horizon but, as they are invisible to the unaided eye, we would need a telescope to see them. Venus the evening star would be visible in the western sky and Saturn in the eastern sky. If at 4 pm Mars, or another planet, had been 30 below the eastern horizon we would now (at 6 pm) be able to watch it rising.
The clock needs daily adjustment as the interrelationships between the planets as well as their positions against the star background are constantly changing. Calendars or an ephemeris are handy but it is possible, if you know the constellations, to look into the sky, note the Moon or planets position and move its magnet to the appropriate position. The Sun provides a challenge in that you have to deduce its position as you cannot see its star background due to the glare. A rough way is to note the first Zodiac constellation visible in the west after sunset . The Sun will be approximately 200 to the west of that. The sky 200 either side of the Sun will be glare. Once you have established the Sun’s position you can move it 10 a day. The Sun moves 3600 (full circle) in a year of 365 days. Therefore the Sun moves just under 10 a day on average.
The Moon moves 12-130 daily and at the other extreme Uranus, Neptune and Pluto you will not need to move on your clock for years.
The Antipodean Astro Calendar and Northern Star Calendar have charts showing the positions for each planet at the middle of each month.
- Fine Tuning the Clock
When you have had some practice with the clock and past the beginners stage you can leave off the horizon profile. This is because in this model the Sun only rises in the east and only sets in the west giving you a constant 12 hour day throughout the year. The reality is different. In Summer the Sun is rising in the south east and setting in the south west and you could be having a 16 hour day. The horizon profile in this model limits the truthfulness of the model. If you like making models it would be better to have a 3600 horizontal horizon profile and a stand that would swivel on the base. The swivel action would overcome the limitation of the clock only rotating about an east-west axis.
The model is an aid to help you to picture various fundamental planetary movements and interrelationships. Once you can easily visualise these, you will no longer need the model.
Learn the names, the sequence and the symbols associated with the zodiacal constellations.
You might like to learn the short poem:-
The Ram, the Bull, the Heavenly Twins
And next the Crab, the Lion shines,
The Virgin and the Scales,
The Scorpion, Archer and Sea Goat,
The Man who held the watering pot
And Fishes with glittering tails.
Isaac Watts (1674-1748)
These are the end of the instructions.
Hopefully they will empower you to enjoy, and get to know, the heavens above a lot more.
Riddles untold in the widths of space,
Riddles untold in the rounds of time!
Only the wakened spirit can solve them,
Holding its own,
Beyond the confines of Space, beyond the flow of time.
TITLE AUTHOR ISBN
Collins Guide to Stars and Planets* Ian Ridpath
Astronomy And The Imagination Norman Davidson 0140190783
Sky Phenomena Norman Davidson 086315168X
Betwixt Heaven and Earth Brian Keats 0646382071
Antipodean Astro Calendar Brian Keats
(annual for southern hemisphere)
Northern Star Calendar Brian Keats
(annual for northern hemisphere)
Local Astronomical Society’s Skywatch Guides
Copyright Brian Keats January 2002