Lunar calendar traces of its origin in the earlier lunar calendar, which continued to be used alongside it for religious and agricultural purposes. Present-day lunisolar calendars include the Chinese, Hindu, and Thai calendars. Synodic months are 29 or 30 days in length, making a lunar year of 12 months about 11 days shorter than a solar year. Some lunar calendars do not use intercalation, such as most Islamic calendars. For those that do, such as the Hebrew calendar, the most common form of intercalation is to add an additional month every second or third year. Some lunisolar calendars are also calibrated by
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