What is the exact date for Vesak Day in years 2009 and 2010?

Vesak in 2009 is on Saturday, the 2nd of May. Vesak in 2010 is on Friday, the 21st of May. From http://www.when-is.com Not exactly, for 2009, Thailand Vesaka Bucha is at 8 May, Singapore is 9 May. It may depend on latitude and longitude. It's on May 8th 2009.In Sri Lanka they use to make wesak lanterns using bamboo and tissue papers. http://image46.webshots.com/46/0/14/92/2226014920011159810LvaHpp_ph.jpg