There are roughly 200 billion stars in the Milky Way and 400 billion trees on Planet Earth. Astronomers and Earth scientists both deal with images at many wavelengths, time series, and catalogues of objects; and to get science out of the data, it is important in both cases to combine multiple datasets. We feel that there should synergies and lessons to learn in each direction about how we deal with these problems.

Here we provide some background on the two sides of this endeavour - Forest Monitoring, and The Virtual Observatory .