The centres of the 12 pentagons are at the points where 5 meridians cross. Two of the 12 centres lie on the equator at the precise moment when the sun passes over the zenith at the Spring ( or vernal 20 March, Aries) and Autumn (23 September Libra) equinoxes. The two centres of the pentagons are on opposite sides of the earth at 0°N 40°W (10° East of the amazon delta) and 0°N 140°E ( a few degrees North of Jayapura, New Guinea)

From these two centres the meridian of the solar ecliptic can be found and naturally, the tropics of cancer and capricorn.

Between the tropics of cancer and capricorn the sun passes over the zenith (90°) when the declination of the sun is equal to the latitude of the place. The declinations of the sun as it enters the different signs of the zodiac are listed below.

Declination

-23°26 21 December Capricorn

-20°09 20 January Aquarius

22 November Sagittarius

-11°28 19 February Pisces

23 October Scorpion

0° 20 March Aries

23 September Libra

+11°28 20 April Taurus

23 August Virgo

+20°09 21 May Gemini

23 July Leo

+23°26 21 June Cancer

Therefore the sun passes over the zenith at latitudes of 23°26S and 23°26N as it enters the signs of Capricorn and Cancer, hence the ‘tropics’ of Capricorn and Cancer. Beyond the limits of the tropics the sun never passes over the zenith.

Six of the 12 pentagons have their centres between the tropics of Cancer and Capricorn. They are at the same latitude as the declination of the sun as it enters the signs of the zodiac in the previous table. Their exact positions are listed below.

23°26S 102°W (7° East of Easter Island) -the sun passes over the zenith as it enters the

sign of - Capricorn

11°28S 26°E (North Western Zambia) - Pisces and Scorpio

0°N 40°W (10° East of the Amazon delta) - Aries and Libra

0°N 140°E (New Guinea)

11°28N 154°W (8° South of Hawaii) - Taurus and Virgo

23°26N 78°E (Nagpur, India) - Cancer