The edge of the Horsehead nebula, where it touches the empty space outside it, is rich in carbon. Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA)
by Michael Burton, The Conversation
The carbon cycle is central to life on Earth. It describes how carbon flows between living organisms, and the ocean, atmosphere and rock of our planet, and is driven by the energy from our sun.
But a carbon cycle also exists for our galaxy, and astronomers are opening new windows into space that let us watch this galactic carbon ecosystem in action.