Well, it’s the last of March, the Eve of April Fools’ Day, and also my birthday.
I am now about 0.04847 years old — wait, that’s Eris years, for the dwarf planet Eris (Eris the mgt.) goes around the Sun once every 557 Earth-years.
Ah, I guess that’s one way of feeling young. In Earth years I’m 27; I have no idea whether that is young, but in my case that ain’t mature yet, not if being mature means prune-faced silence and acknowledging that You Should Conform. (Then again, shrill cries of “I’m a rebel! Honestly! Look at the Iron Maiden decal on my attache case!” are a sure sign of not being young anymore; ah well.)
Also, I’m around one-third of a Uranian year (84 Earth-years) old. Insert the inevitable joke about not being a prune-arsed old coot though I am but a third of Uranus, and so on.
In Venusian years I’m almost 44. That fills me with dread; surely there can be no world where I’m over forty?
112 Mercurian years. Aaargh.
This is all done with the help of Wikipedia, by the way, plucking the orbital period of each planet from there and into my calculator.
You might have noticed I spoke of years and years, though numbers like 0.04847 usually convert down to months and days — that’s because I’m not desperate enough to start thinking how many Saturnine self-rotations or Jovian moon flybys (and which moon?) have gone by since arrived, wet, tiny, and quite puzzled.
Since the timing of my arrival must be a matter of singular indifference to you, consider instead Europa, a moon of Jupiter, that goes around the planet every 3.5 Earth-days (every astronomy-related number in this post is more or less rounded), and rotates synchronously, the same side always facing Jupiter. This would mean that on Europa…
A local year is the time it takes to go around the Sun: an Earth-year is familiar to us, and an Eris-year is around 557 Earth-years.
A local month, relative to some moon, is the time it takes that moon to go around you: on Earth, a Moon-month (heck, a pure bare month) is that thirty or so (see endnote) days it takes for the Moon to go sailing once around us, and on Mars, a Phobos-month would be seven and a half hours, and a Deimos-month would be a day and some six hours.
Now, what the bleeding tick would be a colloquial word for the time it takes you to go around a planet? Both month and day suppose that you’re on a planet and either observe it going around the sun, or a moon going around it.
Clearly, unless we’re going to use this highfalutin’ “orbital period” tomfoolery, we need a word for “the period of time it takes the object I’m on to travel once around the planet or other non-solar body it’s going around”, just like a year is “the period of time it takes the object I’m on to travel once around the Sun“.
This day being what it is, I modestly propose that the word for that be a moe, from “Masks of Eris”, pronounced like the character on the Simpsons.
If on, say, Europa, you would have an (Europan) Jupiter-moe of 3.5 Earth-days.
Or on our own Moon, you could observe an Earth-moe of around thirty Earth-days.
Or, stretching things a bit, on the International Space Station you can talk of an Earth-moe of ninety-one and a half Earth-minutes.
And generally, if X is a planet and Y its moon, the people on X reckon that their X-month (by the moon Y) is of the same length as the X-moe reckoned by the pseudopods on the moon Z. This is useful since if the moon Z has moons of its own, the pseudopods will get plenty confused if they try to use the same word to refer to both movement around them, and their own movement around something else.
You could say that month and moe are body-specific timekeeping measures that look in different directions: month is a word for “reckoning by bodies that orbit me”, and moe is a word for “reckoning by the bodies that I orbit”, leaving, for obvious reasons of tradition, the basest Solar System moe, orbiting around the Sun, to be called a year.
If you are confused, scared and terrified, my mathematical-astronomical-conceptual job is done for yet another day, and we both can move on. Have a nice day.
* * *
Since you have continued reading, I assume you are not terrified yet. Well, then I must pull out, with the help of Wikipedia for refreshing my memory, a mathematical fact that is usually really uncomfortable for the first-timer.
First, consider the decimal number 0.999…, or the number where you have nine tenths, nine hundredths, nine thousandths, and so on, forever.
Okay. That number is the same as one.
That is, .
Are you terrified yet? If not, or if you don’t quite believe a mere assertion (good boy!) or think this is some symbolic nonsense, let me give you a quick, easy proof of this.
You presumably accept that , right? Well, if you take three times the left side, and three times the left side, you still got equals, right? And what you got is exactly what we desire.
This thing is actually a rather nice mathematical fact; Wikipedia has a splendid article on the matter, including more complicated and rigorous proofs and examples of why humans get this burning itch between their brain lobes when trying to understand why ’tis so.
Humans… well, in the academic world there are rocks, plants, animals, laymen (“humans”), students, graduate students, particularly bright pets, and faculty. More or less in that order. (And, as you surely know, the departmental secretary is at the top of the chain. If this is unfamiliar, see the second endnote.)
And, so, a good day to you, too, birth- or otherwise.
* * *
endnote, “a month is around thirty days” : Yes, I know a month is of different length depending on whether you wait for it to return to the same spot by the stars or by the Sun or by the coloring of your trousers; I’m ignoring all that here because it gives me… well, not headache since I almost never get actual physical headache (I’m either too cool, or just a freak of nature), but a deep feeling of nonsensical and existential dread.
* * *
second endnote, on secretaries, or an old, old, old mathematical joke:
- Leaps tall buildings in a single bound
- Is more powerful than a locomotive
- Is faster than a speeding bullet
- Walks on water
- Gives policy to God
THE DEPARTMENT HEAD
- Leaps short buildings with a single bound
- Is more powerful than a switch engine
- Is just as fast as a speeding bullet
- Takes a few steps on water
- Talks with God
- Leaps short buildings with a running start and favorable winds
- Is almost as powerful as a switch engine
- Is faster than a speeding BB
- Walks on water in an indoor swimming pool
- Talks with God if a special request is honored
- Barely clears a quonset hut
- Loses tug of war with a locomotive
- Can fire a speeding bullet
- Swims well
- Is occasionally addressed by God
- Makes high marks on the walls when trying to leap tall buildings
- Is run over by locomotives
- Can sometimes handle a gun without inflicting self-injury
- Treads water
- Climbs walls continually
- Rides the rails
- Plays Russian Roulette
- Walks on thin ice
- Prays a lot
- Runs into buildings
- Recognizes locomotives two out of three times
- Is not issued ammunition
- Can stay afloat with a life jacket
- Talks to walls
- Falls over doorstep when trying to enter buildings
- Says “Look at the choo-choo”
- Wets himself with a water pistol
- Plays in mud puddles
- Mumbles to himself
- Lifts buildings and walks under them
- Kicks locomotives off the tracks
- Catches speeding bullets in her teeth and eats them
- Freezes water with a single glance
- She is God
(Cannot give source; there are myriad versions of this joke and this is a longish one, saved from the net a long, long time ago.)
(Oh, one more thing. This post started with me seeing someone had hit on this blog with a google query “how old would you be on eris”, and I couldn’t think what that could mean except these redefinitions of years and other things.)