years : February 29th, or Leap Day. You know that we have Leap Day to sync up the number of days in a year , because the earth revolves around the sun every...  ...every 365.25 days. We add an extra day every four *strong class="matched-kw...

(YouTube link) You may have noticed that tomorr...  ...t tomorrow is February 29th, sometimes labeled as Leap Day. Even if you haven't, you probably noticed th...  ...the U.S. presidential election is happening this year , which means this is a Leap Year . C.G.P. Grey explains...