Ganesh Chaturthi, also known as Vinayaka Chaturthi, is the Hindu festival centred on God Ganesha, celebrated on Shukla Paksha Chaturthi (fourth day of the waxing moon period) of Bhadrapada month. According to the Gregorian calendar, the days fall in the month of August or September. It is said that on this day, Lord Shiva placed the head of the elephant on Ganesha after he decapitated the boy for stopping him from meeting Goddess Parvathy. He then declared him superior to all the other gods while they blessed him with many more boons.
According to the Hindu calendar, this year, Chaturthi falls on 13th September. If the muhurat begins at night on the previous day and gets over by morning on the next day, then the upcoming is observed as Vinayaka Chaturthi. Normally, Ganpati Visarjan takes place after a day and a half, and on the fifth, seventh and eleventh day of the festival. However this year Gauri Ganpati Visarjan will take place on the fifth day. 7 popular Ganpati pandals in Mumbai to visit this festive season.
In many parts of India, primarily Maharashtra, Gauri is also worshipped along with Lord Ganesha. It is said that Gauri or Goddess Parvati, who is the mother of Lord Ganesha comes down in search of his son during Ganesha Chaturthi. The arrival of Goddess Gauri depends on the status of Anuradha Nakshatra according to the Hindu calendar. Her pooja takes place on Jeshtha Nakshatra and her visarjan takes place on Moola Nakshatra. This year, the arrival of Gauri, or Aavahan as it is called, will take place on the third day of the festival -- on 15th September. And her visarjan along with Lord Ganesha's will take place on 17th September. Why is the festival of Lord Ganesha celebrated for 10 days?
The Gauri Aavahan and poojan can be done any time in the day this year according to famous astrologer Damodar Krishna Soman.