Nivea billboard activated by sun

A billboard for sunscreen in Brazil that can only be seen when the sun shines. Here's how it works. Artist Simon Fernandez used a million beads that change color when exposed to the sun. "Viva o verao de perto" means "Make the most of sumer". At night, all you can see is the text (because that is white, withoud any sunlight-activated beads) while the rest of the billboard is black.