Geocentric Coordinate Time system. When the Earth is at perihelion in January, TCG ticks even more slowly than it does on average, due to gravitational time dilation from being deeper in the Sun's gravity well and also velocity time dilation from moving faster relative to the Sun. At aphelion in July the opposite holds, with TCG ticking faster than it does on average. Geocentric Coordinate Time Geocentric Coordinate Time (TCG - Temps-coordonnée géocentrique) is a coordinate time standard intended to be used as the independent variable of time for all calculations pertaining to precession, nutation, the Moon, and artificial satellites of the Earth.
National Register of Historic Places listings in Central Chicago Chicago architecture. Architect Louis Sullivan's work is represented by the Carson, Pirie, Scott and Company Building, and Auditorium Building. Though Frank Lloyd Wright worked downtown early in his career as an assistant to Sullivan - including work on the James Charnley House - his own work in the central city is represented only by a renovation of the lobby of Daniel Burnham's and John Wellborn Root's Rookery Building. At least three sites relate to the city's role in nationwide retailing. Included also are several religious buildings, six hotels, and four theaters. National Register of Historic Places listings in Central Chicago