- Thanks to the limestone bluffs and hills that surrounded Red Wing, the town became a Minnesota lime-making and stone quarrying center from 1870 to 1910. Those forty years are sometimes known as the city’s “Stone Age.”
- Earth–Moon system (Wikipedia)
The Earth and the Moon form the Earth-Moon satellite system with a shared center of mass, or barycenter. This barycenter stays located at all times 1,700 km (1,100 mi) (about a quarter of Earth’s radius) beneath the Earth’s surface, making the Moon seemingly orbit the Earth.