- 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.
- Ross Dam (Wikipedia)
Ross Dam is a 540-foot (160 m)-high, 1,300-foot (400 m)-long concrete thin arch dam across the Skagit River, forming Ross Lake. The dam is in Washington state, while Ross Lake extends 23 miles (37 km) north to British Columbia, Canada. Both dam and reservoir are located in Ross Lake National Recreation Area, is bordered on both sides by Stephen Mather Wilderness and combined with Lake Chelan National Recreation Area they make up North Cascades National Park Complex.