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
Iditarod Trail Sled Dog Race Seavey with a time of 8 days, 11 hours, 20 minutes, and 16 seconds. As of 2012, Dallas Seavey was also the youngest musher to win the race at the age of 25. In 2017, at the age of 57, Dallas's father, Mitch Seavey, is the oldest and fastest person ever to win the race, crossing the line in Nome in 8 days, 3 hours, 40 minutes and 13 seconds. Dallas finished second, two hours and 44 minutes behind. Teams generally race through blizzards causing whiteout conditions, sub-zero temperatures and gale-force winds which can cause the wind chill to reach