There is no 1st Onam or Second Onam .. Actually Onam celebrating 10 .. 1st day & Last day Onam is important .. Last day is called Thiruvonam .. The day having Thiruvonam star is called Onam Festival .. So Thiruvonam Star commencing today after 4pm today till tommorow 5pm .. So Thiruvonam celebrating tommorow ie) 31st August 2020