Golf ball

A golf ball comprising a core and a cover, wherein the cover is formed primarily of polyurethane, the ball has a diameter of at least 42.8 mm and a weight of not more than 44.9 g and, in an impact test carried out by fitting a golf swing robot with a metal head driver having a loft angle of 9.5°, striking the golf ball at a head speed (HS) of 40 m/s, photographing the golf ball during impact and analyzing the captured images, the sum t1+t2 of the time t1 required from initial contact by the driver with the ball for deformation of the ball to reach a maximum state and the time t2 required from the state of maximum ball deformation for the ball and the driver to separate is not more than 660 μsec, and wherein the maximum state is the instant at which the diameter of the golf ball in the direction of flight from the plane of contact between the clubface and the ball reaches a minimum, and

• wherein the core has a diameter of at least 37.0 mm and a hardness profile in which, letting Cc be the Shore C hardness at a center of the core, Cs be the Shore C hardness at a surface of the core, Cm be the Shore C hardness at a midpoint M between the core center and the core surface, Cm−2, Cm−4, Cm−6 and Cm−8 be the respective Shore C hardnesses at positions 2 mm, 4 mm, 6 mm and 8 mm inward from the midpoint M and Cm+2, Cm+4 and Cm+6 be the respective Shore C hardnesses at positions 2 mm, 4 mm and 6 mm outward from the midpoint M, and defining surface areas X and A to F as follows
• 1/2×2×(Cm−6−Cm−8) surface area X:
• 1/2×2×(Cm−4−Cm−6) surface area A:
• 1/2×2×(Cm−2−Cm−4) surface area B:
• 1/2×2×(Cm−Cm−2) surface area C:
• 1/2×2×(Cm+2−Cm) surface area D:
• 1/2×2×(Cm+4−Cm+2) surface area E:
• 1/2×2×(Cm+6−Cm+4), surface area F:
• the core satisfies the condition:
• (surface area D+surface area E+surface area F)−(surface area A+surface area B+surface area C)>0.