DateTime::Astro implements functions used in astronomical calendars: - Solar Longitude - Solar Terms - Lunar Longitude - New Moons ... etc This module is best used in environments where a C compiler and the MPFR arbitrary precision math library is installed. It can fallback to using Math::BigInt, but that would pretty much render it useless because of its speed and loss of accuracy that may creep up while doing Perl to C struct conversions. WWW: http://search.cpan.org/dist/DateTime-Astro/