UGears is proud to present the Mechanical Tellurion, an accurate wooden model representation of our corner of the universe. A tellurion (also spelled tellurian, tellurium, and sometimes called a loxocosm), is an ingenious mechanism that depicts the cosmic dance between Sun, Earth and Moon. The causes of day and night, the phases of the moon, and the changing seasons are seen and understood according to the movements of this 3D puzzle. Turn the handle to set the closely calibrated system of gears in motion. One turn of the handle = one rotation of the earth on its axis = one day. Point to a spot-on Earth's surface, observe the spinning earth's position relative to the sun, and visualize sunrise and sunset, the passage of day into night. The Tellurion shows the phases of the moon are a function of the moon's position relative to the sun and earth. When rotating, the moon rises and falls slightly, thereby changing its trajectory. The earth's orbit around the sun, together with a correct depiction of the 23.5-degree inclined orientation of the earth on its axis, shows why we experience changing seasons (outside the equatorial regions). The Tellurion charts the passage of the seasons, while also giving a handsome graphic representation of the zodiac, showing the sign and constellation under which you were born.

It can be manually adjusted or "tuned" to provide an accurate depiction of the relative positions of the sun, earth and moon on any given day. When "tuning" the mechanism, set the pointer to the middle of winter or summer on the seasons dial. The earth, on its tilted axis, can be rotated (using a gear under the phases of the moon) to have either hemisphere be farthest from the sun in the bleak midwinter, or closest to the sun in summer. Turn the handle the correct number of days forward or back, from whichever solstice is closest in time, to set the present day. After consulting a lunar calendar, use the upper gear disk to adjust the position of the moon to its correct phase. Your Tellurion is now "set." With each passing day, give the model one turn of the crank to chart the earth's progress around the sun, and the moon's lunar cycle as it orbits the earth. At UGears, a rough approximation or "close enough," isn't really our style. In representing the orbital periods of our planet and the moon, our design engineers have given the Mechanical Tellurion a sophisticated gear system (first worked out by Dutch mathematician Christiaan Huygens in the 17th C) to have the most accurate approximations possible in a wooden mechanism at this scale. The earth gearing has a 365.256-day orbital period, while the moon-earth gear system has an orbital period of 27.323, giving accuracies within one thousandth of a day.

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Warranty applies to any damaged or defective part within 30 days of purchase.