Whether you like it or not, today may be the real 'Earth Day'. The famous Arch Bishop James Ussher Chronology states that God created the world on the evening before October 23, 4004 BC. This date is followed by many in the Reformed faith as well as many evangelical Christians.
So, if you are a big-time creation science person- happy earth day. Almost all of creation science dating is based on Arch Bishop Ussher's work.
On a personal note, I do not think that we should be too dogmatic about 4004 BC, and definitely not dogmatic about October 23rd... nevertheless, it is fun part of our Christian heritage to note that men have spent substantial time and energy attempting to figure out when God created the world.
Buy Ussher's work here.