(NASA)When the sun was a newborn and Earth was in its infancy, the solar system could be a cruel and chaotic place. The presence of a large, rocky satellite gave Earth a partner and protector in its dance around the sun. For 4.5 billion years the moon has stabilized Earth’s tilt, lengthened its days, summoned its tides. Our moon is uniquely large for the solar system; whereas Mars’s largest moon weighs less than 0.0000017 percent of its planet, the moon’s mass is roughly 1 percent of Earth’s. Its craters reveal periods of asteroid bombardment that pummeled the inner solar system.

Source: Washington Post June 18, 2019 15:00 UTC