Wanted to share the astronomical importance of the time frames which we observe as festivals or feel auspicious days.
At first, As we all know the inner planets and outer planets , for getting an accurate calculation our rishis made earth as center ( Geo-centrical ) and replaced earth with Sun.That is why, we say sunrise and sunset but where actually we (Earth is ) are rotating in the 360 degrees circular zodiac . Names of the months are given based on moons position on the full moon day of the every month , for Example, Moon on”Chitra nakshatram” on the pournami day of the month is named as”Chaitra Maasam” similarly”Visakha naskhatram” as”Vaisakha Maasam” etc…. Now chitra nakshatram in the zodiac is pointed at the end of kanya ( Virgo ) raasi and starting of Thula ( Libra ) , but the question is the constellations start from Aswini so why is not the Aswayuja masam the first month of the year , we start our hindu year with Chaitra Maasam middle of the zodiac.
The reason is in Chaitra Maasam sun transits on Aswini nakshatra which literally means earth, as we replaced it with sun because of Geo-centrical calculations , so sun ( I.e earth ) transiting the first star in the middle of the month is the first month chaitra maasam and so on months occurs.
Now earth while revolving around sun towards northward on the celestial sphere will go closer to sun where we get summer season and sunlight will be brighter for us. Now at current period that is in Aswiyuja masam earth will be transiting on the southern side of the celestial sphere and little far away from the sun and, we get winter season , These ten days of the Navarathri earth will be at the center of the zodiac at the 180th degree point , Hence it is observed as most powerful and auspicious time where we should be more keen in practicing religious activities , if you observe keenly the first navaraathri’s , that is”Vasantha navarathri” comes when earth is at 0 degree point and second navarathri is this”Sarannavarathri” at the 180th degree point of the 360 degrees zodiac.
I know this info is a little confusing and lengthy to read , yet very valuable to recognize our ancestors’ knowledge on celestial objects way before so-called science was born.
Once again Happy Dussehra. God bless you all.