Lunar month circular, the speed of Earth's progression around the Sun varies during the year. Thus, the angular rate is faster nearer periapsis and slower near apoapsis. The same is so for the Moon's orbit around the Earth. Because of these variations in angular rate, the actual time between lunations may vary from about 29.18 to about 29.93 days. The long-term average duration is days (29 d 12 h 44 min 2.8016 s). The synodic month is used to calculate eclipse cycles. It is customary to specify positions of celestial bodies with respect to the vernal equinox. Because of Earth's precession of
Dundrod Circuit the 2017 Ulster Grand Prix. The race record for the Dundrod Circuit is an average speed of set by Bruce Anstey during the 2017 Ulster Grand Prix. The lap record for the RAC Tourist Trophy on the Dundrod Circuit is 4 minutes and 42 seconds at an average speed of 94.67 mph (152.3582 km/h) held by Mike Hawthorn driving a Jaguar D-Type set during the 1955 RAC Tourist Trophy. The race record for the RAC Tourist Trophy on the Dundrod Circuit is 7 hours, 3 minutes and 12 seconds an average speed of 88.32 mph (142.139 km) for 84 laps