一个公历年有 365.2425 天：
1 year = 365.2425 days = (365.2425 days) × (24 hours/day) × (3600 seconds/hour) = 31556952 seconds
一个儒略天文年有 365.25 天：
1 year = 365.25 days = (365.25 days) × (24 hours/day) × (3600 seconds/hour) = 31557600 seconds
一个公历年有 365 天：
1 common year = 365 days = (365 days) × (24 hours/day) × (3600 seconds/hour) = 31536000 seconds
一个日历闰年有 366 天（每 4 年发生一次）：
1 leap year = 366 days = (366 days) × (24 hours/day) × (3600 seconds/hour) = 31622400 seconds