Q: New Year

[AmitaSarin at aol.com]

I'm curious to know why April 13th is the solar New Year for so many Indian
communities.  In Punjab also, Baisakhi celebrates the New Year on the same
date.  The Persian New Year Navroze, however, although also solar, is on the
21st of March.  Other Indian solar festivals, Pongal in Tamil Nadu, Lohri in
Punjab and Makara Sankranti in many other regions, are celebrated around the
13th/14th of January.  Most other Indian festivals - Diwali, Holi, Dussera
etc. are calculated on a lunar system and do not have a constant date on the
western calendar.  
Can anyone explain the origins of these two systems?    
Thanks, Amita Sarin