Nadir is employed during remote sensing of the atmosphere, as well as when an astronaut faces the Earth while performing a spacewalk. The term nadir can also be used to represent the lowest point reached by a celestial body during its apparent orbit around a given point of observation. This can be used to describe the location of the Sun, but it is only technically accurate for one latitude at a time and only possible at the low latitudes. The sun is said to be at the nadir at a location when it is at the zenith at the location's antipode
Point-to-point transit focus cities. In Europe, for example, most traditional full-service airlines operate seasonal point-to-point service outside their hubs to serve Mediterranean and Alpine holiday resorts. Point-to-point transit Point-to-point transit refers to a transportation system in which a plane, bus, or train travels directly to a destination, rather than going through a central hub. This differs from the spoke-hub distribution paradigm in which the transportation goes to a central location where passengers change to another train, bus, or plane to reach their destination. The point-to-point model is used widely by low cost carriers, including Allegiant Air and Southwest Airlines in the U.S.,