Its a well known fact that time has seconds as one of the smallest measure. The Pendulum was the first instrument to measure second. There are other lower measures of time like nano seconds.
Minutes, hours, days weeks, month,years are the other ways to denote the passage of time. All of them are usual except for a week and month.
The revolving of the moon around the earth could almost take a month and that could be the reason of the origin of Month. I could remember the school days when i was taught the number of days in a month(30 or 31) based on the position of knuckles.
Because there isnt much significance in a week and month as per scientific issues but still its widely accepted. The other important aspect is that we rest(or given holiday) once in a week. the only solution we can get to know about week is in holy books of Hindu, Muslim and christianity(and also Jews) and may be even in Chinese ancient literatures. The most oldest claim of a week could(may) be in bible(and torah) which starts with a week and offcourse it says about the rest day(sabath). We can say that in a day the earth rotates once and in a year the earth revolves around the sun. But we cant say any such thing for a week except that we can see seven palnets in the night sky. i havent tried that though.
Lets get to other important events(on time) that might come in a year: A leap Year and a leap Second. We all know about the leap year. The rotation of the earth is slowing down at some rate each day. It is not a constant rate at which it slows down. So inorder to keep the time accurate, they observe a leap second in a day. There were 23 occasions from 1972 where a leap second was annnounced or introduced in a year.
Equinox are the days when the the earth has 12 hours of day and 12 hours of night. And the shortest day (winter solstice)and longest day (summer solstice)are either july 20-23 or december 20-23 depending on the hemisphere. Solar eclipse and lunar eclipse are two special phenomenon that might come in a year. But they dont have any significance in the time scale in earth.