As we celebrate the 40th birthday of Earth Day today, many events to commemerate the anniversary are taking place, including a charitible event that involves the best nature photographs of all time... The top 40 nature photographs of all time will be auctioned off in the inaugural "Green Auction" at Christie’s in New York City this evening. Funds raised will go to conservation organizations worldwide.The collection represents a range of styles and spans 100 years of the history of photography. They were chosen by members of the International League of Conservation Photographers and among the photographers honored are Galen Rowell, Nat Geo's Editor in Chief Chris Johns & shown below, Thomas D. Mangelsen, whose "Polar Bear Dance" is a big web favorite! (These two could've taught Kate Gosselin a thing or two...Alas, too late!) To see a slide show of this image and 9 others to be auctioned off this evening, you can click onto FoxNews' slide show here: http://www.foxnews.com/slideshow/scitech/2010/04/20/best-nature-photos-all-time/?slide=1 and you can visit www.abidtosavetheearth.org for more information. ("Polar Bear Dance" photo by Thomas D. Mangelsen/ Mangelsen Stock/iLCP Collection).