Telling Time

At the Encyclopedia Foundation, we are obviously big fans of science fiction. And yes, we are nerds, in that we take it seriously to the extent that even while enjoying it, we nit pick it and try to one up each other on who can spot the glaring scientific flaws in it. Star Trek obviously provides fertile ground for this (and for those who enjoy that kind of thing, google “SF Debris” and watch his great reviews) and as to Star Wars…let’s not get us started!

One of the favorite things to show in both sci fi movies and to be described in sci fi books is also one of the more laughably inaccurate things we know of. That’s where a spaceship arrives at a new star system, and they basically look out the window and see the planet, big and bright, right in front of them. Then they can pretty much manually fly the ship straight into a parking orbit. Wow. So easy.

Kind of hard to reconcile that with how hard it was for those who actually live in that star system. For assuming that other aliens are not much smarter or dumber than we are (a reasonable assumption for reasons not relevant to this article), they would have had a hard time finding all their planets themselves.

Take our own species, since obviously that’s the one we know best. It took us quite awhile to discover all of our planets, and Pluto wasn’t discovered until the 20th century. (Yes, I know what the IAU said!) You see, planets don’t actually give off light. Sure, they reflect light, but this just means that entering our Solar System would be like entering an area 20 football fields long. In the center, a bowling ball is glowing not much brighter than the other stars. And somewhere there are nine items ranging in size from a pinhead to a chestnut. Earth would be a peppercorn.

Care to guess how long it would take you to notice the reflection off of a peppercorn in circle two kilometers in diameter? And what if it was on the wrong side of the Sun to observe the reflected light? And you are not an entity the size of a human wandering about those hundreds of football fields looking for a peppercorn. No, you are the size of an atom, and are looking about that giant sphere, 20 football fields in diameter, and oh, yeah, it’s not just two dimensions! That peppercorn could be 2 kilometers above you or below you, or anywhere in between!

Or do you use your “sensors” to find the planets? One wonders what science fiction writers imagine “sensors” to be. Apparently things that let them scan a volume of space inconceivably vast for the few rocks or wisps of gas we call “planets”. After all, the diameter of the Solar System – if we confine ourselves to Pluto being the end – is very roughly 4 billion miles in radius. Or 67 billion cubic miles in volume. And 99.85 percent of all matter in that vast volume is the Sun. And the planets are part of the remaining .0015%.

Oh, and whatever those “sensors” are, Pluto is about four light hours from the Sun. So this hypothetical spaceship “scans” and one single beam the send out takes 16 hours to get all the way to the opposite end and return with whatever information it might be able to pick up. Even if we assume their “beam” is one mile in width…well, I’m not going to do the math on that, but suffice to say, that ship had best have a sustainable environment.

What we have are telescopes and math. And the couple of centuries it took when we got serious about finding the not so obvious planets. What they apparently have in books and movies is magic. But I suppose that’s understandable. Imagine if every time the Enterprise entered a new stellar system, Captain Picard announced, “All hands, you have two weeks leave to play in the holodeck while cartography pulls double shifts looking for the planet we were sent to!” (This assumes the planet is unoccupied, or by radio waves they could simply be given instructions as to where to go, though one can imagine the “no, no, my left and down” hilarity that could entail!)

(Note to sci fi nerds: The solution is that an arriving ship would confine itself to the “life zone”, greatly reducing the area to be searched. That would still be an enormous volume. But if they observed some gas giants, and could orient on the planetary plane, this would allow them to position their ship “above” or “below” the sun, closer than 90,000,000 miles to it, so that they could look about in a roughly 300,000,000 mile circle for a planet. A series of rapid photographs of each segment would be taken, and a computer would check all the thousands of photos for any points of reflected light that were changing position. Time to do this would involve many variable factors. Have they spotted a gas giant, thus being able to determine the galactic plane? How long did it take the ship to reposition within the star system? How fast are their telescopic cameras? I am picturing anywhere from a single day to months. But not seconds, minutes or hours. And a day would seem to involve some advance knowledge, some lucky breaks, or a staggering array of telescopes.)

The late great Dr. Isaac Asimov actually discussed some of this in his Foundation series, when he had Golan Trevize explain some of the difficulties in finding planets to Janov Pelorat. More notably, Robert Heinlein mentioned telling time by the planets in “Time Enough for Love” when a time traveler was going to look at the position of the planets, input them into a computer that had the data on those planets, and thus know when he was. He pointed out that unless you already had all the data on the planets, it would be easier just to ask a native what year it was!
Granting then that finding planets isn’t always as easy as it’s made out to be, can one in real life tell the time by the planets?

Yes. The planets of our Solar System have given speeds and rates of rotation and rates of revolving about our Sun that are well known, well documented and susceptible to analysis. We know where each of the planets are right now. That is, when we wish to view one, we do not then spend months or years scanning the sky hoping to come across it and recognize it – we know where it is supposed to be, and we aim our telescopes there.

We are at a point in our history where we can do this now. But we have not always been. And may not always be. So it would be wise to get a series of static shots of our Solar System now, while we can. But how does that work, what good does that actually do?

The means of telling time by the planets is simple to say, harder to do. It takes into account the varying speeds of the planets revolving about the Sun. Earth takes (obviously) one year to do this. Mars, roughly twice as far, takes 1.88 of our years to make a circle (actually an ellipse) about the Sun. Jupiter, about 12 years. Pluto (I know!), about 248 years. Mercury, conversely, only about 88 days.
Western man loves clocks, and it was Lorenzo Valpaia who in the 16th century built a very clever one that was designed to show the motions and position of the major planets. Regrettably it was destroyed. But it shows it can be done. Were a new version to be built – and I think it would be great if one was – it could have a Pluto that literally took about 247 years to circle one time. And a Jupiter taking 12 years. And even “fast” Mercury taking 88 days. (His was not configured to show a literal motion, but did show where they’d be.)

However, more simply than a clockwork mechanism or an orrery, which might not last 10,000 years, would be to have still shots of the configurations of the planets at given intervals. And all the information on the planets, how to observe them, the math involved, as described in other articles.

A person coming across this in, say, the year 6,011, might have an entirely different system for naming years. To him, it may be 441 AC (After the Cleansing) as he counts from the destruction of civilization by rogue nanites that took place 441 years before his present. Or he may think of it as 5432 AH, due to an Islamic civilization having gained world wide supremacy some millennia before.

Whichever years he uses, the odds of it being ours would seem small. However, he may yet have some knowledge of our history. He may have been taught by an Imam that man set foot on the moon in the year 1390 AH, and he could then see by a chart of historical events that we called 1390 AH “1969 CE”. A one to one correlation could be made, and all our data would make sense in historical context.

But possibly he thinks in terms even worse for us – such as regarding it as the eleventh year of the reign of Emperor Daly LXII of the Chicago Imperium, Lord of the Eastern Dominions, Protector of the Western Wastes. If he is an educated man, he may know his emperors back for more than a few centuries. However, ultimately, if knowledge of Common Era dating has been lost, it would be difficult to get a one to one correlation with our historical dates. The time before Emperors may just be a murky “ancient times”, and while they could learn all about it from our books, they’d not know for sure how long had passed since then, unless there had been a fortuitously – and improbably – unbroken line of Imperial succession back to some historical date we already knew of.

This is where the static pictures of the Solar System would come in handy. Once they know what they are, they can chart the skies for what the configuration is during their time. And as the math works backwards as well as forwards, they can know what it looked like a year or five years or 1,000 years ago. Or 4,011 years ago, back to the year 02000 CE.

And given that we’d have those pictures, one of each millennia, possibly each century, they could quickly (well, okay, not so quickly, but at least surely) find out how long ago things like the moon landing were in relation to them. The hypothetical Chicagoan scholar could report to his Imperial Highness that “the moon landing of the ancients took place 2157 years before the ascension of the First Emperor. Our year, by the ancient’s dating, is 6,011. And our observations show that the planets were in the exact formation shown on this plate 11 years ago, at the time of your coronation.”

And thus time can be told again, and all humanity, past and present and future, is on the same page again. This may seem unimportant, but as any disaster could happen any time, and inevitably some disaster will happen some time, such records of the planetary configurations and what they correspond to would be (and will be) invaluable.

So much so that at the Encyclopedia Foundation, we are going to see about adding such to our collection.