concept

The green gap

The stretch in the middle of the visible spectrum — roughly 500 to 600 nm — where chlorophyll absorbs only weakly, so green light mostly bounces off or passes through a leaf. The oddity is that our Sun delivers most of its photons right there, meaning life on Earth left the richest part of the sky on the table. Two credible explanations: either the ancestors of plants grew up beneath purple bacterial mats that had already claimed the green photons, or absorbing on the two flanks rather than at the peak buys a steadier energy supply, sparing the machinery from surges that would wreck it. Do not conclude that green light is useless: because it is absorbed weakly it penetrates deeper into a leaf and feeds cell layers the blue and red never reach.