Constellation, Sidereal Zodiac, and Tropical Zodiac Dial

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:
  1. Carefully cut out the small Tropical Zodiac Dial on the outermost circle.
  2. Poke a small hole in the center of the Tropical Zodiac Dial.
  3. Poke a small hole in the center of the big Constellation/Sidereal Zodiac Wheel.
  4. Insert a brad into the Constellation/Sidereal Wheel from the bottom.
  5. Place the Tropical Zodiac Dial over the Constellation/Sidereal Wheel.
  6. Now you can spin the Tropical Zodiac Dial.
Things to Observe:
  1. No constellation is exactly 30 degrees. Find the longest and the shortest constellations.
  2. The sidereal zodiac signs mostly align with the constellation of the same name, but not perfectly, due to unequal size of the constellations.
  3. 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.
  4. Spin the Tropical Dial slowly CLOCKWISE to show effect of precession, one degree per 72 years. One entire spin equals almost 26,000 years.
  5. 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.
  6. 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.

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