28 2 / 2012

jtotheizzoe: This might be a horrifically stupid question but how does a leap year work? Like, with space and the time it takes to make a revolution around the sun? I thought that’s what determined the length of our days, so every four years do we wobble off our axis? Also, you’re blog is the most informative and interesting blog, ever! Not horrifically stupid at all. Leap years are pretty odd. You’ve gotta realize that leap years are purely man-made. They don’t have to exist. Without them, the Earth would continue to orbit around the sun for the foreseeable future, with no care of how long it took to do so. But people care. We care. We have seasons, calendars, birthdays … our cultural milestones depend on a nice orderly calendar. At least for most of human history, anyway. Leap years exist because the Earth actually takes ~365.25 days to orbit the sun. If we didn’t correct for this, our calendar would be off by several hours every year. So we add a day to make up for it, assuring that equinoxes, seasons and other human calendar comforts proceed without confusion. Can you imagine if all of a sudden December was during springtime? Santa would get sweaty. Here’s the rules for determining a leap year: The year is evenly divisible by 4, AND If the year can be evenly divided by 100, it is NOT a leap year, UNLESS The year is also evenly divisible by 400. Then it is a leap year. So 2000 was a leap year, but 2100 will not be. This is because the orbit is a little less than 365.25 days when you start carrying out the decimals. In closing, thank you. I’m glad you think this is the most interesting blog ever!

jtotheizzoe:

This might be a horrifically stupid question but how does a leap year work? Like, with space and the time it takes to make a revolution around the sun? I thought that’s what determined the length of our days, so every four years do we wobble off our axis? Also, you’re blog is the most informative and interesting blog, ever!

Not horrifically stupid at all. Leap years are pretty odd.

You’ve gotta realize that leap years are purely man-made. They don’t have to exist. Without them, the Earth would continue to orbit around the sun for the foreseeable future, with no care of how long it took to do so. But people care. We care. We have seasons, calendars, birthdays … our cultural milestones depend on a nice orderly calendar. At least for most of human history, anyway.

Leap years exist because the Earth actually takes ~365.25 days to orbit the sun. If we didn’t correct for this, our calendar would be off by several hours every year. So we add a day to make up for it, assuring that equinoxes, seasons and other human calendar comforts proceed without confusion. Can you imagine if all of a sudden December was during springtime? Santa would get sweaty.

Here’s the rules for determining a leap year:

  • The year is evenly divisible by 4, AND
  • If the year can be evenly divided by 100, it is NOT a leap year, UNLESS
  • The year is also evenly divisible by 400. Then it is a leap year.

So 2000 was a leap year, but 2100 will not be. This is because the orbit is a little less than 365.25 days when you start carrying out the decimals.

In closing, thank you. I’m glad you think this is the most interesting blog ever!

Permalink 101 notes