Armillary Sphere Working model to understand Ecliptic

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Let us understand the movement of the Sun throughout the year with this simplified version of the armillary sphere. • This is a simplified version of an Armillary sphere. • It is an early astronomical device used to represent various celestial objects and related terms. • Brahmagupta,(AD 628) a famous indian mathematician and astronomer in his book Brāhmasphuṭa-siddhānta devoted complete chapter to Armillary sphere also known as Gola-yantra. • The armillary sphere was used as a teaching device and not a measuring tool. • Armillary means consisting of hoops and rings. • These two rings represent the celestial sphere. • This is the celestial North Pole. • This is the celestial South Pole. Ring has degrees marked on it on the upper part. • This is the celestial equator. • This tilting plane represents the Observer's horizon. [Earth] which is at 90 degrees to the observer's latitude. These are the cardinal directions for the Observer. East West , North and South. • The Equator and Poles of the Celestial sphere can be considered as an extension to the Earth’s equator and poles. • This outer ring represents Ecliptic. This is the path Sun takes throughout the year. It is inclined at an angle of 23 and half degrees to the celestial equator. • Celestial sphere rotates while the Earth or horizon in the middle remains stationary. • This is our SUN. • The Sun moves on the Ecliptic east to west one revolution per day, but also has a long term motion west to east along the ecliptic of 1° per day. • Calendar marked on the ecliptic can be used to position SUN to understand movement on 21st Mar - Vernal Equinox, 21st June Summer Solstice , Autumn Equinox - 21st September and Winter Solstice 22nd December. • Whole sphere can be tilted like this. Platform can be adjusted to remain horizontal after the tilt. • Calendar on the ecliptic will help in understanding various concepts. • At these two points, the ecliptic crosses the celestial equator. • This is Vernal Equinox - March 21st • This is Autumnal Equinox - Sept 21st • Maximum elevation of the ecliptic above the equator is the point of Summer Solstice. Longest day of the year June 21st • This point is the Winter Solstice - Dec 21st. • Let us tilt the plane for location Pune India which is at a latitude of approximately 18 degrees N. • North celestial pole has an altitude of 18 degrees. • Celestial equator is 72 degrees above the horizon. • Lets position SUN here. This point is vernal Equinox - March 21st. When days and nights are equal. At this point celestial equator and Ecliptic meet at a point. SUN moves along the celestial equator. • On this day, SUN rises exactly in the East and sets exactly in the West. • Summer solstice is on 21st June. Sun rises north of East and sets North of West. • Sept 22 is Autumn Equinox. Sun rises exactly in the East and sets exactly in the West. • Dec 22 is the winter solstice . Shortest day and longest night in the Northern Hemisphere. On this day SUN is at its lowest daily maximum elevation. • How about the North Pole ? Let's place it vertically up like this. • Can you guess the duration of days and nights at different times of the year ? • Planning to use metal rings instead of plastic one in the next version with more markings • This is the first version I built with acrylic and 3D printed parts. Ecliptic was inside and too small to cover the letters. • Planning to replace existing plastic rings with metal ones. • Credits • I would like to thank https://astro.unl.edu/ for educating me on this interesting early astronomical device. • Thank You. • #astronomy • #geography • #sun

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