Friday, April 22, 2011 is Earth Day across the US.

Earth Day began on April 22 in 1970, making this the 41st Anniversary. The first Earth Day, according to Wikipedia, was originally a teach-in held by US Senator Gaylord Nelson, and 20 million people participated. It is now celebrated in 175 countries, and over 500 million join in.

Earth Day in Baltimore brings a number of activities to celebrate.

In Towson, the Towson ARTS Collective has an exhibit, “The Process of Peace”, running through May 20. Friday is a free reception from 6-8 pm to celebrate Baltimore Earth Week’s 8th Anniversary.

On Saturday, The Maryland Science Center in Downtown Baltimore will have Earth Day and recycling activities from noon-4pm which is included in the cost of admission.

The Irvine Nature Center in Owings Mills has multiple events going on Saturday — with the Junior Naturalists in the morning, and then “rainy day” Earth Day activities from 1-2:30pm. They’ll be using broken crayons, old magazines, and more to recycle into new products and projects! For non-members there is a cost.

The Oregon Ridge Nature Center in Hunt Valley will also have its’ “Earth Day Greening” from 1-4pm, where those ages seven and older will be able to help plant trees, and assist in cleaning up the trail & park. This event is free!

You can always celebrate Earth Day at your own Baltimore home too. Plant trees, change lightbulbs to those that use less energy, turn off lights when you are not using them, and recycle materials!