when did tennis balls changed from white to yellow
Tennis ball Modern tennis balls must conform to certain criteria for size, weight, deformation, and bounce criteria to be approved for regulation play. The International Tennis Federation (ITF) defines the official diameter as 6.54–6.86 cm (2.57–2.70 inches). Balls must have masses in the range 56.0–59.4 g (1.98–2.10 ounces). Yellow and white are the only colors approved by the ITF, and most balls produced are a fluorescent yellow known as "optic yellow", first introduced in 1972 following research demonstrating they were more visible on television.
Tennis court Of the current four Grand Slam tournaments, the Australian and US Open use hard courts, French Open is played on clay, and Wimbledon, the only Grand Slam to have always been played on the same surface, is played on grass. The Australian Open switched to hard courts in 1988 and in its early years the French championship alternated between clay and sand/rubble courts. The US Open is the only major to have been played on three surfaces; it was played on grass from its inception until 1974, clay from 1975 until 1977 and hard courts since it moved from the West Side Tennis Club to the National Tennis Center in 1978.