Scientists use the term "dark energy" to describe the mysterious phenomenon that our universe is expanding at an accelerated rate.

We don't yet know what dark energy is. But we might soon find out, thanks to the work of scientists at Kitt Peak National Observatory in Arizona.

Follow their story in this MNN exclusive film.

Bryan Nelson ( @@brynelson ) writes about everything from environmental problems here on Earth to big questions in space.

'Streetlights of the Universe': Can we solve the mystery of dark energy?
"Streetlights of the Universe" is an MNN exclusive film by Bryan Nelson that follows three scientists trying to solve the mystery of dark energy by mapping it.