Harvard University

Astronomy Lab and Clay Telescope


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The Spectrum of the Blue (or cloudy) Sky

Spectral lines are universal signatures of elements; for example, sodium lines have exactly the same wavelengths from our lamp as in the Sun, if we measured in the center of the Sun where there is no radial velocity componet from its rotation. Precise measures of the wavelengths of lines seen from stars can be used to uniquely identify the elements. We are not going to point the telescope at the Sun because the Sun is much too bright for our detectors. We will instead point away from the Sun to capture the sunlight scattered by the earth's atmosphere towards our detector.