What's My Age Again?

This nifty little website will calculate how old you would be if you had been born on one of the solar system's other planets. It apparently dates back awhile and still includes Pluto as a planet, a status astronomers revoked back in 2006.

When I entered my birthday, I found out that my age varied widely depending on what planet I was considering -- I am nearly two centuries old on Mercury, for example, but on Mars I just passed the legal age three years ago, on Jupiter I'm not quite ready for preschool and on Pluto I'm just starting to recognize the giant male and giant female who are always around as specific individuals who are somehow important to me.

Of course, these "years" represent how long it takes the respective planets to orbit the sun. One orbit Earth orbit around the sun equals one year. We get to say that because we're the ones doing the counting; should there turn out to be Mercurian or Jovian life forms we can discuss it then. Mercury, being much closer to the sun than Earth is, goes around it much faster. Mercury takes just under 88 Earth days to complete an orbit around the sun, so Mercury's years are much shorter when measured in terms of Earth's days than Earth's years are. Jupiter, quite a bit of a ways beyond us, is slower. It takes it a little under a dozen Earth years to make a single Jovian year.

The calculator also gives you your age in days on the planet chosen -- that is, the number of times that planet has turned on its axis since you were born. Again, we got to pick, so one rotation of the Earth on its axis equals one Earth day. The speed of rotation depends on a lot of factors, not just distance from the sun. Although second from the sun, for example, Venus has such a slow rotation rate that its year is actually longer than its day. I would be fewer Venusian years than Venusian days old if I had been born there. Mars turns on its axis just a little bit slower than the Earth does, meaning my age in Martian days is just 400 days less than my age in Earth days, out of a total of about 17,000.

One neat feature of the page is that it will calculate when your next birthday on that planet would be, given the birthday you enter and the number of Earth years it takes for that planet to get around the sun. I am highly likely to see my next Mercury birthday (it's next week), Venusian birthday (next January), Martian birthday (next month, about a week after my Earth birthday) and my next Jovian birthday (next February). I can reasonably expect to see my next Saturnian birthday (2023; I'll be 59) and could very well make it to my next Uranian birthday (2048; I'll be 84). On the other hand, I'll have to be a record setter extraordinaire to see my next Neptunian birthday (2129; I'd be 165) and I imagine some sort of amazing medical developments will have to have happened for me to see my next Plutonian birthday in 2213, when I would be 249. And probably telling those 150-year-old punks to get off my lawn.

There's apparently a wrinkle in the website algorithm though, because it predicts that my next Earth birthday will happen a day after it actually does. No big deal to me now, but that sure would have been a bummer back in 1980 as I would have had to have waited another entire day to get my driver's license. Which wouldn't be nearly as bad as if I had been born on Pluto, because I would not get my license there until sometime in 5948.