Lunar eclipses occur whenever the full moon passes into the shadow of the earth.
Solar eclipses occur when the new moon slips in front of the sun and blocks it from view. The moon's shadow then falls upon the earth. The eclipse occurred on Leap Day, February 29, 1504. Columbus probably consulted an astronomical almanac such as the Calendarium of Regiomontanus to obtain full details of both eclipses. Over 2000 years before Columbus' voyages, the ancient Chinese and Babylonians had discovered a cycle that could be used to predict both lunar and solar eclipses.