The earth is painted green with chlorophylls, the molecules that harvest solar energy and funnel it into the photosynthetic system that converts it into sugar molecules. Chlorophyll a is bright blue-green, chlorophyll b a more muted olive color. The a form dominates the b by 3 to 1 in most leaves, but the balance is evener in plants that grow in the shade, and in aging tissues, where the a form is degraded faster. The chlorophylls are concentrated in cell bodies called chloroplasts, where they’re embedded in the many folds of a membrane along with the other molecules of the photosynthetic system. Each chlorophyll molecule is made up of two parts. One is a ring of carbon and nitrogen atoms with a magnesium atom at the center, quite similar to the heme ring in the meat myoglobin pigment. This ring portion is soluble in water, and does the work of absorbing light. The second part is a fat-soluble tail of 16 carbon atoms, which anchors the whole molecule in the chloroplast membrane. This part is colorless.