Celebrities paid tribute on Twitter, mourning the loss of the American hero.

Renowned astrophysicist Neil deGrasse Tyson wrote, Arent many Heroes left, before listing Glenns impressive accomplishments.

Thanks for your dignity and bravery and for opening the universe to all of us.

ALL CROPS: 150803741 Astronaut and former Ohio Senator John Glenn talks to members of the media prior to the game between the Cleveland Indians and the New York Yankees at Progressive Field on August 26, 2012 in Cleveland, Ohio

Credit: Jason Miller/Getty Images

The heavens are now yours.

Read a sampling of reactions below: