What the turn of the century does for leap year

Know All, See All Matt: I have two friends who differ about leap year in the year 2000. One friend says February 29 does not occur on a century mark, while the other friend argues that in the year 2000 there will even be one extra day more, February 30, because the earth’s speed and rotation still give us extra time after all the other February 29ths pass by. Who’s right? A third friend’s birthday is February 29, so I need to know. — Bernie in Kearny (Mesa)

Start scouting the malls for a gift, Bernie. Only 1272 more shopping days till February 29, 2000. And while you’re at it, pick up a couple of calendars for the other two. Consider this traditional memory aid to help the three of you keep track of time. “Thirty days hath September, April, June, and November. All the rest have 31, except February, which has 28, except in years evenly divisible by 4, when it has 29, except in years evenly divisible by 4 that end in 00, when it has 28, except in 00 years evenly divisible by 400, when it has 29.” The last leap year on a century mark was in 1600; the next will be 2000. Your March rent will be a day late if you believe that February 30 fantasy. Should I even mention that we add leap seconds to our years (on June 30 or December 31) to keep Earth clocks in synch with the less-regimented solar time? Naw, you’ve got enough troubles already.