Astronomy Picture of the Day . The Color of the Moon . ... The familiar Sea of Tranquility ( Mare Tranquillitatis ) is the blue area right of center. White lines radiate from the crater Tycho at bottom left, while purplish tones mottle the crater Copernicus left of center. ... Calibrated by rock samples from the Apollo missions, similar multicolor images from spacecraft have been used to explore the Moon's global surface composition. ... Publications with keywords: Moon - color . ...