Sundial - Hemispherium

thingiverse

Note: dial46.5degreesN.stl is a custom-made dial for my specific latitude. For step-by-step instructions on how to create your own dial, see "How I Designed This". A Hemispherium is an educational sundial that showcases the Earth's motion around the sun in a visually engaging way. By placing the shadow of the sun on a partial sphere, it clearly demonstrates the sun's apparent motion through the day and year, including Daylight Saving Time (Summer Time) effects, solstices, equinoxes, and calendar development. This sundial is particularly useful for illustrating how time can be determined not only by the hour but also by the season. The design emphasizes the importance of understanding solar time in relation to standard timekeeping methods used in watches and clocks. The celestial equator is marked on this sundial by a long line. When the gnomon's shadow crosses this line, it signals the arrival of Spring (Vernal) or Fall (Autumnal) Equinox. The upper edge of the partial sphere represents the Tropic of Capricorn. As the gnomon's shadow touches this edge, it indicates the Winter Solstice in the Northern Hemisphere and marks the sun's lowest point in the sky for that day. Conversely, the lower edge of the partial sphere marks the Tropic of Cancer. When the gnomon's shadow reaches this edge, it signifies the Summer Solstice in the Northern Hemisphere, where the sun is at its highest point in the sky. The short lines on this sundial divide the partial sphere into 24 equal parts, each representing an hour of the day. These evenly spaced divisions are a result of dividing the total degrees in a circle (360) by the number of hours in a day (24), yielding 15 degrees per hour. A noticeable gap within the partial sphere signifies solar noon, the time when the gnomon's shadow falls into this specific area, indicating that the sun is at its highest point in the sky for that particular day. While standard watches and clocks display Standard Time or Summer Time, a solar time sundial offers a more intuitive representation of the sun's movement through the sky.