Earth's age is often debated, but Earth Day is 43 years old today.
Earth Day was born in 1970, a creation in large part of efforts by Gaylord Nelson, a Democratic U.S. Senator from Wisconsin, who died in 2005.
Denis Hayes, the national coordinator of that first day, said that he thought it had achieved many of its aims, despite the challenges of modern times.
Earth Day is designed to "[activate] individuals and organizations to strengthen the collective fight against man's exploitive relationship with the planet."
As for the outlook on Earth Day 2013?
"Beyond any doubt," he told The Guardian (UK), "today the basic core values are vastly more 'green,' if you will, than they were in the 60's and 70's."
It's true that the green movement has crept into our daily lives in many simple, yet profound ways. But there is also much more work to be done.
While climate change has become a political lightning rod, we can all likely agree that protecting biodiversity and natural resources are good things.
Also, the natural beauty of Earth is pretty spectacular.
The milestone is marked by one of Google's annual doodles today, a tradition for the tech giant. Here's a screen shot of Monday's animated logo:
The pastoral scene of hills, snowy mountains and a lake teeming with fish is a either a nod to the circle of life, the hydrological cycle ... or just looks neat.
You can also click on it and it does cool stuff.
What can you do on Earth Day 2013? The simplest, most apolitical way to make a difference? Grab a trash bag and some gloves and pick up your street.
Seriously. Litter sucks.