It's part of a project with Nickelodeon. The network is urging children to turn off their lights for one minute to show their commitment to saving energy.
The Empire State Building and Space Needle in Seattle will take part as well.
State's first hybrid school bus
Earlier on Wednesday, some students in south suburban Olympia Fields celebrated Earth Day by riding on a green school bus Wednesday morning.
It is Illinois' first hybrid school bus and only one of 25 hybrid school buses in the country.
Students who didn't get to ride the new bus were able to take a tour once it arrived at school.
The bus is powered by an electric battery and a diesel engine. It's quieter, cleaner, and twice as fuel efficient as a regular school bus.
Quinn to make mansion more eco-friendly
Also on Wednesday, Gov. Pat Quinn marked Earth Day by ordering state agencies to reduce waste. He's also taking steps to make the governor's mansion more eco-friendly.
The governor's mansion is reducing electricity use by installing LED lights. The mansion will also use barrels to collect rainwater for gardening.