Over six years ago I wrote a post on my old Blogger blog about what I believed the exact middle of the year was. When I had written it, I remember feeling that the computations that I did were faulty since there was just something odd about the numbers I was getting.
Today, I remembered about my old post, on this year's "Middle of the Year Day," and wanted to revisit the computations that I used. Re-reading the post, the computations made logical sense, but, again, the result just felt wrong. Especially when you introduce leap seconds into the logic, things became much more murky. But then I realized something simple that I had actually accounted for, but was subtle and forgotten as you continued to read the post: the calculations that the exact middle of the year was made by grouping 4 years together, and dividing the four into equal pieces. Therefore, the calculation of the time of July 2nd at 15:04:34 is not "the exact middle of the year", but rather the "quarter marker of the current leap year cycle". In other words, on July 2nd at 15:04:34, we would be crossing another 25% through the current leap year cycle (in my parlance, a "leap year cycle" is every 4 years).
However, we do not usually look at the calendar and think about time in 4-year cycles. We usually subdivide time based on our non-scientific concept of a year, which means 365 days on a non-leap year and 366 days on a leap year. Thus, given this, the middle of the year - to the hour - is July 2nd at noon on a 365 day year. According to Wikipedia, we keep July 2nd at noon as the middle of the year on leap years too.
But, then there are timezones, so July 2nd at noon occurs at different times for different timezones. If you remained in the same timezone throughout the year, then the exact middle of the year would be July 2nd at noon for you, but if you were in Los Angeles and talked to someone in New York, you would find that they had their exact middle of the year 3 hours before you. To alleviate this discrepency across timezones, we could use a common timezone, UTC (or GMT), and just change the time for everyone depending on where you are in the world. Thus, if the exact middle of the year is July 2nd at 12:00 UTC, for myself living in the Los Angeles timezone, the middle of the year is July 2nd at 5AM (UTC-7 during summer time; or 4AM if you don't take into account Daylight Savings, which is UTC-8). So, depending on how you look at time, you could celebrate the middle of the year at either noon or whatever time noon in UTC is in your own timezone.
So, six years ago, I sought to find the exact middle of the year, and over the last half decade, the concept of the "middle of the year" became complicated by leap years and seconds and timezones, and just the general perception of time. Though I may have missed this year's crossing into the last half of the year, I feel better in knowing that I was wrong, because being wrong gave me the opportunity to look back at the question, and gave me the opportunity to evaluate my findings in a broader context.