Earthshine Project


The Earth's climate depends on the net sunlight deposited on the globe, which is critically sensitive to the Earth's albedo. A global and absolutely calibrated albedo can be determined by measuring the amount of sunlight reflected from the Earth and, in turn, back to the Earth from the dark portion of the face of the Moon (the `earthshine' or `ashen light').

To make a systematic determination of the the Earth's albedo, a groundbased earthshine observing project, supported by NASA, was re-started at Big Bear Solar Observatory in the summer of 1998. The project is led by Prof. Goode, director of Big Bear Solar Observatoy, and Prof. Koonin at California Institute of Technology. A detailed description of the project is available here.

We take the nightly observations using our earthshine 'coronagraph' and its Apogee7 digital camera. Reports of the nightly observations are available here. The data are analyzed to obtain the Earth's albedo from the ratio of the earthshine intensity to the moonshine intensity. From this, an accurate calibration is achieved. Preliminary results also can be viewed here.

In the meanwhile, we analyze daily cloud-cover data from Intellicast and compare the result with the analysis from the observed earthshine. The integrated albedo obtained from our observations will then provide a unique check on recent 'scene' models, the description of which can be seen here.

The earthshine logs can be found here.

The Science May 28 earthshine images may be found here.


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© BBSO/NJIT - Last modified: May 26, 2004.