- A sphere (from Greek σφαῖρα, sphaîra) is a geometrical object that is a three-dimensional analogue to a two-dimensional circle. Formally, a sphere is the set of points that are all at the same distance r from a given point in three-dimensional space. That given point is the center of the sphere, and r is the sphere’s radius. The earliest known mentions of spheres appear in the work of the ancient Greek mathematicians.
- Bay Area Rapid Transit (Wikipedia)
Bay Area Rapid Transit (BART) is a rapid transit system serving the San Francisco Bay Area in California. BART serves 50 stations along six routes and 131 miles (211 kilometers) of track, including a 9-mile (14 km) spur line running to Antioch, which uses diesel multiple-unit vehicles, and a 3-mile (4.8 km) automated guideway transit line serving the Oakland International Airport. With an average of 146,500 weekday passengers as of the fourth quarter of 2022 and 41,286,400 annual passengers in 2022, BART is the fifth-busiest heavy rail rapid transit system in the United States.
