Traditional dandiya raas.
www.flickr.com user euthman
It happened last year and it's going to happen again this year -- although Navaratri is usually a nine night festival, it will only have eight nights in 2012. The festival gets underway on October 16 and ends with Dussehra on October 24.
The reason why is because of how the Hindu calendar, which is based on lunar cycles, functions. Astrologically, days 3 and 4 (Sindoor Tritiya and Varad Vinayak Chaturthi) both occur on the same date -- October 18. More information about this is available on Hindu Blog.
Find out about how Navaratri is celebrated and the best places to experience it in India.