A hotly-debated subject is at last put to rest as scientists announce that they have conclusively confirmed that there is, in fact, life on Earth. They discovered this by looking at the Moon. It may seem like a pointless exercise — but this discover could help us find life on exoplanets.
It has long been rumored, despite many satirists' claims to the contrary, that the Earth was capable of sustaining life. That rumor could never be substantiated, since all professional biologists had an obvious economic interest in confirming the rumor. At last astronomers were able to step in and put the controversy to rest: There is life on Earth.
There were three major astronomical players helping in this discovery; the Earth, the sun, and the moon. The sun projects light out towards the other objects, the Earth reflects light, and some of that reflected light hits the moon, which then reflects that light to telescopes. Looking at that light's polarization allowed scientists to determine the atmosphere of the Earth, and spot life on its surface.
Light comes out of the sun without any polarization whatsoever. However, when light hits a surface, for example the flat surface of a pond or the glass on a window, it reflects from that surface with all its waves oscillating in the same direction. Looking at polarized light can show the properties on a planet's surface. And then there's circular polarization. This is when the waves spin around in circles as they travel. Scientists looked at the waves coming off the leaves of plants and showed that the light coming off the surface of the leaves was circularly polarized.
Scientists have also observed a 'red edge' - a high incidence of reflected light between the 700 and 750 nanometer wavelength range - which keeps the plant cool and keep the chlorophyll from degrading inside it. Seeing a high degree of reflection in this range indicated vegetation on the surface of the planet.
By observing the polarity and the color of the light from the Earth reflected from the moon, scientists were able to determine that the Earth is cloud-covered part of the time, that there are oceans on Earth, and that there is vegetation on the Earth's surface. Although it may be some time before these techniques can be applied to exoplanets, climatologists, oceanographers, and botanists will be gratified to know that their work can now be accepted by the scientific community. Since animal life can't be confirmed yet, zoologists will just have to hang in there.