Archive for the 'Astronomy' Category

Calendar Reform

Thirty to forty thousand years ago, our ancestors were hunter-gatherers. Life was short and brutish, and dentistry had not been invented. Anatomically, people were just like us, lacking only our effortlessly cynical attitude. Try if you can to imagine life before fast food, deodorant, and digital stereo. Unlike us, they were not obsessed by “stuff,” since they could only use what they could carry around. The oldest human artifacts ever found date from this time. They are calendar sticks — portable pieces of wood with notches carved into them to count cycles of the Moon or Sun.

Our ancestors absolutely depended on keeping track of the time. If they foraged during the day, they would have to begin to return to camp before the Sun reached its highest point in the sky. Otherwise, mmmmm, crunchy snack for a saber-toothed cat. Keeping track of the seasons allowed them to predict when to find their favorite foods. These foods did not have names yet, so they were known as “the bright red berry that is sweet but goes right through you” or “small furry animal that tastes like pork gone off.” Each winter the shortening days and shallow slanting rays of the Sun would signal the time to migrate back to the Florida timeshare.

Five or six thousand years ago, tribes around Europe began to build large stone circles. These were multi-use buildings, Stone Age versions of a church or a town hall. The stones were perfectly aligned to mark out the positions of sunrise on the longest or the shortest day of the year. Everyone’s heard of Stonehenge, which rises like a pile of giant kid’s blocks out of a meadow in southern England. Stonehenge is now used only by modern pagans, a free-spirited tribe that annoys the hell out of the Brits who can’t shit anything larger than a BB.

Here’s the trouble with calendars. The time it takes the Earth to spin once on its axis is a day. The time it takes for the Earth to return to the same place in its orbit of the Sun is a year. If there were a whole number of days in a year, keeping track of time would be no big deal.

But there are not 365 days in a year. There are not even 365¼. There are 365.242199 days in a year. So if your calendar has 365 days, you are about 6 hours short. After 100 years, that 6 hours has accumulated into 600 hours, or nearly a month. This calendar will get steadily out of whack with the seasons. OK, you think, let’s do the leap year thing. That brings the average to 365¼ days in a year. But 365.25 is not the same as 365.242199. The tiny difference of 1/100 of a day grows into a whole day after 100 years and ten days after 1000 years.

Why not use the Moon to make a calendar? There are about 29½ days in a lunar cycle. Trouble is, 29½ doesn’t divide neatly into 365¼. It goes 12 times with 11 days left over. So a lunar calendar slips with respect to the seasons at a rate of one month every three years. Every 35 years, a lunar calendar shifts through an entire solar year.

The entire Arab world uses the Moon for their calendar. Check it out in any encyclopedia — the Islamic countries are those with a crescent Moon in their flags. They ignore the Sun for keeping time, which is a cunning strategy in a part of the world where you can fry an egg on the sidewalk most times of the year. As a result, Ramadan and the major Arab festivals could fall on any day of our calendar. Timekeeping depends on direct observation of the Moon (the word moon comes from the Greek metron, to measure). Until the new sliver of Moon is actually observed on the ninth month of the lunar cycle, the minaret hollerers cannot declare party time in Mecca. A few clouds in the wrong part of the sky, and all those camels stuffed with donkeys stuffed with goats stuffed with pigs have to be put back on ice.

They say that science marches forward. Well, the science of calendars is full of anachronisms and oddities. The Babylonians had a calendar that was accurate to 30 minutes a year over 5000 years ago. Europe did not equal it until 4500 years later. When the Spanish conquered Central and South America, they trashed the local culture and customs (but that gold work is nice, yes, we’ll take that, and here, have some devastating diseases while we’re at it). Yet, among other things, the Maya and Inca calendars were far superior.

If our culture is so advanced and rational, why do we have to remember a little ditty to figure out the number of days in each month? Why did February get left short? Why do the last four months of the year come from the roots of the words for 7,8,9, and 10, when we have 12 months in the year? Why does the year start at the beginning of January? Why does Easter shift around in the calendar, while Christmas always falls on the same day? Who thought up this stuff anyway?

The Romans. In the 7th century B.C., the time of Romulus, the ancient Romans were just one of many warlike tribes scattered through Europe. They kept track of time vaguely, with a calendar of ten months that alternated 30 and 31 days. The year started sometime in March, because that was when the snow in the Alps melted enough for the Roman legions to go off and kick some serious butt.

So the year began with March, named after the god of war. Then came April, after Aphrodite, the goddess of beauty. Next was May, after the ancient fertility god Maia. Then June, after Juno, the goddess of women. But the Romans were simple folk. Violent, but simple. After they had run through their gods, they named the rest of the months after the numbers 5 to 10. This calendar of just over 300 days makes a poor apology for a year.

In the 6th century B.C., the emperor Pompilus added two short months of 25 days each to the front end of the year. January was named after Janus, the god of doorways and beginnings, and February was named after the festival of purification. A bit later, the emperor Priscus made more adjustments. He bumped up the length of the first two months.

However, the Romans were incredibly superstitious. Black cats, ladders, broken mirrors, salt tossed over the shoulder — you name it, they had a hand in passing it down to us. Even numbers were bad luck, so the months alternated 29 and 31 days. Under the principle that “shit happens,” the Romans came up with the clever idea of concentrating misfortune in one month. February became the short month with an unlucky 28 days. It was too cold to raise a legion and make war. It was too dark to go to the forum and see a good disemboweling. No Roman would travel at all in February. For the entire month they would hole up and satisfy carnal urges, with occasional trips to the spa or the vomitorium.

This flaky calendar became intolerable by the time of Julius Caesar. Caesar tweaked the calendar to make a neatly alternating pattern of months with 30 and 31 days. (February remained the unloved child with 29 days.) He added a day every fourth or leap year to make the average year last 365¼ days. With an ego as big as the Colliseum, Caesar grabbed the first unnamed month for himself. So Quintilus (the number 5, but the 7th month) became July. Emperor Augustus followed. His ego matched Caesar’s, and so he nabbed Sextilus as his month. Thus we have August. But Augustus saw that his month was shorter than July, so he added a day to it, and then had to adjust other months and the pattern got screwed up forever.

Why do we start the year on January 1st? The Earth repeats its orbit of the Sun endlessly and we could start the year on any day. The real reason was so Christianity could get a jump on the pagans. Since the dawn of time, humans have been Sun worshippers. Stonehenge and all those other rock piles were built to mark the longest and shortest days of the year. The biggest cheers were saved for the time just after December 21st, when the sunset position starts moving back to the north and the Sun makes a higher and warmer arc in the sky.

So early Christian leaders placed Christ’s birthday just after the winter solstice (the Good Book makes it clear he was born much later in the spring). And they co-opted the pagan calendar by starting our year on January 1. It was all a way of making converts to this new religion. This schizophrenia is really apparent in the case of Easter. In the Bible, Easter is set by the lunar calendar and should not always fall on a Sunday. Easter flops around in our calendar because it is the first Sunday after the first full moon that falls after March 21st. And March 21st is — you got it — the spring equinox, another pagan holiday. Orthodox Jews and the Eastern Orthodox group got fed up with this kluge and split off to follow their own lunar calendar.

It must have been a hard sell for those early Popes. You can have Christianity, with cold stone pews, turn the other cheek, and no real fun until the hereafter. Or you can go with paganism, which has lots of body painting, dancing, and free sex. What would you choose?

Paganism still looks pretty good. It’s an official religion in most parts of the United States. So you can claim all eight pagan holidays, the cardinal points of the solar year. In addition to the solstices and the equinoxes, there are the mid-points between them: February 1st, May 1st, August 1st, and November 1st. Most of these have long been forgotten, but we still celebrate the last as Halloween.

Even Caesar’s nifty calendar was not the final answer. It is a bit longer than the Earth’s orbit, and so by the 16th century the calendar was 10 days out of synch. In 1582, Pope Gregory added the bit about skipping leap years in century years unless they are divisible by 400. This gives a most excellent calendar, guaranteed to keep the seasons lined up thousands of years after humans have been wiped out by prions or bombs or whatever other damn fool thing we dream up.

Out of anti-papal pique, the mostly Protestant England and United States put off converting to the Gregorian system for another 170 years. And so April 1st, 1752 was followed by April 12th, as the slack was taken up overnight by government decree. (The mostly Catholic French mocked this late switch by inventing the idea of April Fools day.) Ben Franklin wrote in Poor Richard’s Almanac to reassure people over the “loss” of their 11 days. There were widespread riots anyway.

The French, bless their garlicky little hearts, once tried a rational scheme. After the French Revolution was over and all the loose heads had been cleaned up, the communal government declared a calendar of 12 thirty-day months, plus five festival days. Free of pagan relics, the months had names like Meadow, Mist, and Blossom. The festivals were titled Virtue, Genius, Labor, Opinion, and Reward. There was a ten-day week. Every day had ten hours, each of 100 minutes, each of 100 seconds. It was totally cool and post-modern. The trouble was the rest of Europe, which trundled along with the old system. Commerce became a nightmare. So after twelve years of the experiment, Napoleon kissed the ring and came back into the fold.

So here we are, stuck with pagan relics and Roman ego trips. Surely there is a better way. Me? — I’m signing up with Islam. That lunar calendar sounds pretty good right now.

Chicken Little

was right. The sky really is falling. Maybe not today or tomorrow. And not necessarily on you. But eventually, and without a doubt, a big hunk of space junk will fall out of a bright blue sky and ruin our collective day. A hard rain is gonna fall.

Big meteorites are the cruel trick that space plays on life. Like the kid at playschool that waits until you have painstakingly built the Lego city and then smashes it to the ground. Evolution is the slow process of accumulated change where organisms adapt to the world and take their place in the Chain of Being as either an eater or an eatee. Nothing dramatic, one generation looks much the same as the next. It takes many millions of years to grow a claw, or a penis, or a wing. Then in comes a big piece of space junk and overrides natural selection by wiping out a good chunk of life’s rich diversity.

The Romans called it decimation — the random removal of ten percent of the population. They would march into a newly conquered town full of skulking goths or visigoths and kill one in ten just to maintain fear and public order.

Out there in space it’s like a big old grinder. Asteroids and big chunks collide and make debris of smaller pieces. Collisions are rare because the space between space rocks is so large, but over billions of years large gets ground down into small. The result is a sparse interplanetary beach, with a few boulders, a bunch of pebbles, and countless grains of sand.

This stuff rains in on Earth at speeds of tens of thousands of miles per hour. Luckily the atmosphere burns up most of the small chunks. Yet every day, a trillion or so dust motes from space settle onto the Earth’s surface, and about a million sand grains fall. How do we know? After all, dirt from space looks just like dirt. Scientists go down to the perfect blue-white ice pack of the Antarctic, and the space dust is just lying on the surface. Nothing else there, except the occasional penguin. So they push sticky rollers up and down the ice to trawl for the dust, like crazed Zamboni drivers on an ice rink.

Larger space junk is rare, but more worrying. Every week or so a car-sized chunk careens toward us. Most of these break up or detonate in the upper atmosphere, with the force of a Hiroshima blast. In the early 1960s, during the frosty depths of the Cold War, both sides noticed these atmospheric blasts. Each side assumed the other was welshing on arms agreements, and nervous fingers were poised over buttons. Scientists figured it out and the Dr. Strangeloves went back to their bunkers. But debris from space nearly pushed us over the nuclear brink.

About once per century a rock the size of a small apartment building slams into the Earth and makes a crater five football fields wide. The last time it happened was in Siberia in 1908. An area of forest the size of a big city was leveled and tremors were felt as far away as London. Siberia is big and empty so almost no one was killed. Some herdsmen were burned, one was thrown into a tree, and a few were thrown off their porches. Many more must have felt the blast and looked with new respect at their jug of potato vodka. With the last jolt nearly 100 years behind us, you can do the math. We’re due.

Then there are the big sonsofbitches. About every million years, a meteor the size of a small mountain hits Earth and flattens an area the size of Belgium or New Jersey. Such an impact would be seriously bad news (unless you have no sympathy for really bad drivers and really bad sports teams), releasing an explosive force equal to a billion tons on TNT, or the sum of all the world’s arsenals. Hundred-foot tidal waves would sweep across the oceans, throwing enough dust into the atmosphere to dim the Sun and cause massive crop failure and famine. And these are not the really big impacts.

Don’t ask. You don’t want to know. Oh, all right. Every hundred million years, give or take ten million, a monster the size of a city nails the planet. The oomph is ten million times that of Mount St. Helens blowing its top. There’s nowhere to hide. Thousand-foot tidal waves circle the world over and over. Global forest fires rage. The sky darkens long enough to disrupt the food chain. Plankton die and grass withers. Extinction. Bummer.

Sixty five million years ago a monster rock slammed into the Gulf of Mexico. Its effect would even have penetrated the margarita daze of the partiers in nearby Cancun. For tens of millions of years, mammals had scurried around nervously in a reptile’s world. Then the Big One falls and the dazed mammals are left to inherit the world and eventually spin off an unfinished experiment called humanity.

It makes you think about destiny. Somewhere out there is a silent assassin sailing through space with our number on it. The events that will bring it on a collision course with the Earth have not yet taken place. Maybe it is a comet. On one of its passages from the deep-freeze of the solar system it gets a nudge from Neptune then a tug from Jupiter and then it’s trawling through the inner regions where the terrestrial planets dwell. Many orbits later, its trajectory will cross that of the innocent Earth. As an outfielder races across the grass toward the lazy arc of a fly ball, the two objects will meet in space and time.

Do you have an irrational fear of meteoric impacts? Let’s look at that. The rarest condition is a level 1 phobia — the fear of mass extinction by a catastrophic collision. Its most acute sufferers glance nervously upward every few minutes. They make no long-term investments. They know that the impactor will travel much faster than sound, and they imagine it is streaking towards them. In their minds, they freeze the instant when it is poised just overhead; a mountain looming in the sky as they walk to the Quickie Mart.

Relax. Take a load off. At one event in tens of millions of years, the chance of the Big One in our lifetimes is tiny. The human race is much more likely to be taken out by its trashing of the environment than by a rock from the sky. Anyway, our weapons guys have got it covered. Out at Los Alamos and Livermore, they have thought about this a lot, since Ivan has been de-fanged and we have all these useless piles of plutonium glowing among the yucca and mesquite of the western deserts. Astronomers scan the skies to look for anything large headed in our general direction. We then use supercomputers to calculate the orbits. Only if a big object is truly headed our way do we send out the nukes to save the day. It’s got to be done delicately, with a bank off to the side like a good pool shot. Nailed head-on we face a hail of deadly bullets instead of a single cannonball.

Level 2 phobia is fear of medium-sized impacts. Every thousand years or so, a country or region of the world is thrown into turmoil when the sky is lit up by meteors and people die as a few big chunks get through the atmospheric shield. Is it a coincidence that a new major religion springs up about every thousand years?

If you suffer from this fear, the only therapy is to start your own cult. Find some chunk of eastern Oregon that isn’t already taken by militias and declare yourself the Bhagwan of Tunguska. File for tax-exempt status and gather as many gullible minds as you can. (Plan on turning many people away…) As for the form of your new religion, the constitution pretty much allows you to roll your own. A mixture of yoga, micro-brewing, and free sex is highly recommended.

The fear of a personal impact is a level 3 phobia. Every year, about 100,000 chunks of space rock that are small but big enough to kill you hit the Earth’s surface. Most of them fall into the oceans and most of the rest must hit land that does not happen to have a person standing on it. But every now and then, someone’s in the wrong place at the wrong time. What are the odds?

In 1650, a monk in Milan was praying when he was killed by a meteorite. That God, he’s such a kidder. This century, we know only of a dog killed in Nahkla, Egypt in 1911. (Dogs reading this are probably thinking, what does he mean “only.”) There have been close calls. An Alabama woman was asleep when a meteorite came through the roof and ricocheted off her hip, burning her badly. Mrs. Hodges survived to become the person with the best ever story to tell at a cocktail party. Two houses in the same small town of Wethersfield, Connecticut were hit within a span of eleven years. In 1992, Michelle Knapp’s 1980 Chevy Malibu was hit in the trunk by a 30-pound meteorite. The space rock fused with her car, so collectors offered $69,000 for the whole thing.

Maybe you’re getting twitchy by now. But that’s not a long list given the huge number of people in the world. Your odds of dying from a meteorite impact are about the same as your odds of dying from botulism. You are 100 times more likely to die in an air crash and you are 10,000 times more likely to die in a car crash. We all gotta go sometime, and it might be better to be taken out this way. It’s quick, it’s relatively painless, and you would get commemorated in the name of the bolide that hit you. Beats an old gravestone covered with moss and dog pee any day.

Let’s face it, we’re not very rational about risk. We lock our doors at night, then drive without a seat belt. We watch our cholesterol count, then have unprotected sex. So if you still have some residual phobia, here are practical tips to avoid being nailed by space junk:

1. Don’t fly. The atmosphere is your friend, burning up most of the rocks that meet us from space. When you fly, you place yourself above most of that cushioning layer. Plus do you really think those guys up front ever concentrate on what they’re doing?

2. Sleep standing up. Surface area is the problem. The bigger the target, the bigger your chances to getting hit. So lose a few pounds by all means, but also reduce your impact area by favoring the vertical over the horizontal. Mrs. Hodges had no one to blame but herself. Try sleeping in your closet hanging in a sleeping bag.

3. Build a bunker. After midnight, the Earth’s forward rotation combines with its motion through space to increase the chances of a meteorite making it to the ground. In the early morning hours, and during any meteor shower, you are far better off surrounded by cans of Spam and your favorite CDs in the bomb shelter.

Sweet dreams and don’t look up!