This is a precessional dial.This clever device shows:
- The constellations
- The Sidereal Zodiac — so you can see that the signs do not exactly match the constellations
- A Tropical Zodiac removable dial which will spin, demonstrating the effects of precession
*Some assembly required. I developed this so I could understand precession better. It worked for me, and hope it works for you, too! Enjoy!
To create your own Tropical Zodiac Dial, follow these simple steps:
- Carefully cut out the small Tropical Zodiac Dial on the outermost circle.
- Poke a small hole in the center of the Tropical Zodiac Dial.
- Poke a small hole in the center of the big Constellation/Sidereal Zodiac Wheel.
- Insert a brad into the Constellation/Sidereal Wheel from the bottom.
- Place the Tropical Zodiac Dial over the Constellation/Sidereal Wheel.
- Now you can spin the Tropical Zodiac Dial.
Things to Observe:
- No constellation is exactly 30 degrees. Find the longest and the shortest constellations.
- The sidereal zodiac signs mostly align with the constellation of the same name, but not perfectly, due to unequal size of the constellations.
- Once the Tropical Dial is attached, line up 0 degrees Aries on both zodiac circles. This is approximately equivalent to the time 200 C.E.
- Spin the Tropical Dial slowly CLOCKWISE to show effect of precession, one degree per 72 years. One entire spin equals almost 26,000 years.
- Currently, the difference between the most common sidereal zodiac and tropical zodiac is almost 24 degrees. Therefore 0 dcgree of Aries in the tropical zodiac is equivalent to 6 degrees of Pisces sidereally.
- Notice that 0 degrees Capricorn Tropical – the Winter Solstice — is aligning with the Galactic Center, located at 3 – 6 degrees of the Archer (27 -Sagittarius to 0 Capricorn tropically). Solstices align with Galactic Center twice in 26,000 years.