EARTH -Scientists have come up with an entirely new way to monitor the health of Earth’s plants from space

Watching the planet breathe -  it is possible to pick up the chlorophyll fluorescent light that plants give off, a glow that can’t be seen with the naked eye, but that can be seen with the right instruments. (Plants photosynthesize, they use energy from sunlight to turn carbon dioxide from the air into sugars used to live and grow).
Global map of plant chlorophyll fluorescence is measured by the GOSAT satellite.
http://www.physorg.com/news/2012-03-planet.html