2028
Friday, 15 October 2027
In 2027 the tithi runs from 6:49 pm on 14 Oct to 7:17 pm on 15 Oct; it is running at moonrise on Friday, 15 October 2027, so that is the day of Sharad Purnima.
2029
Sunday, 21 October 2029
In 2029 the tithi runs from 12:32 pm on 21 Oct to 2:57 pm on 22 Oct; it is running at moonrise on Sunday, 21 October 2029, so that is the day of Sharad Purnima.
How the date is fixed
Sharad Purnima falls on the full-moon day (Purnima) of the lunar month Ashwina. The date is the day on which that tithi is running at moonrise.
About
Sharad Purnima is the full moon of Ashwina, in October, the first full moon after the monsoon clears. It is a night observance, so the day whose night carries Purnima is chosen, and the Moon's rising is the moment that matters. The Kojagari vigil of Bengal and Mithila is kept for Lakshmi, who is said to ask 'who is awake' (ko jagarti); in Braj the night recalls the raas of Krishna. Kheer is left in the moonlight and eaten the next morning.
How it is observed
A night vigil with Lakshmi worship, and kheer kept under the full moon.