I've always found space fascinating, and among my first books was a book about astronomy. It was just a small, general guide that had a number of interesting facts about the solar system and the stars and galaxies. This was 1980 or before, and we've made a LOT of discoveries since then, and I've kept up on it, partly thanks to Ars Technica, the Science Channel, and NASA.
Today's topic: the third rock from the Sun, known to the locals as Earth.
There's a lot about the Earth you don't know. I could fill the entire internet with that kind of thing, and in fact, lots of people are doing just that. So instead of me giving you a list of interesting physical facts about the place you live, I thought I'd share with you an essay I wrote many years ago for school, to help human minds grasp just how enormous the universe is. Enjoy!
We are Tiny
We are tiny. The world we live in is huge. We don’t really grasp how small we are, because we can see maps of the whole world, and we can travel to the other side of it in the space of a few hours or days. We can drive a mile in a minute or less, we can fly a mile in a few seconds, we have spacecraft that can travel a few miles in 1 second, but what if you had to walk? It takes about a third of an hour to walk a mile. Not a whole lot of time in the scale of our lives, but we get tired of it after only a few miles. It would take about two years to walk all the way around the Earth.
There are a lot of things on the Earth that you have never seen before, and may have read about in books, but what about if you hadn’t had those books? You would think these things mostly tall tales, told to amuse children, or the boastings of drunks. It would take too much time and money to go traveling. Something like Disneyland would be a life’s aspiration rather than one choice among many.
The Solar system today is much like the Earth of just 100 years ago. Sure, spacecraft can fly several miles in a second, but with the number of miles to travel, we may as well be walking. It takes days just to reach our nearest celestial neighbor: the moon. It takes months or years to reach the world we are most likely to colonize next: Mars. It would take centuries or millennia to reach the closest visible star: Alpha Centauri. This is a journey the likes of which no one has ever experienced, and no one can really imagine it.
Our knowledge is growing. As we before could not imagine traveling to the ends of the Earth in a mere day, one day we may be able to go much faster than we do now. But even if we are able to instantaneously reach the speed of light itself, the nearest star is still over 4 years away, a journey even Magellan and Drake did not know, and there will be no stops along the way to reprovision or let the crew out to relax and blow off steam.
The galaxy is huge. At the speed of light, it would take about 100,000 years to cross it. This is a journey so huge the mind cannot hope to comprehend it. Along the way, you would see strange things that you didn’t think were possible, and people you tell your stories to would not believe you.
Let us suppose it is possible to build a warp drive, capable of traveling 1000 times the speed of light. A journey to Alpha Centauri would take only a day and a half; still a long time by today’s standards, and no reason to commute to work; it would be equivalent to a long train ride, from one side of a continent to the other. The galaxy-spanning trip still requires 100 years to accomplish.
So let us build a warp drive that travels a million times the speed of light. It now takes about 5 weeks to cross the galaxy; an hour’s travel will carry you over 26 lightyears away; there are an awful lot of visible stars within that range, and quite a few more that we don’t yet know about.
But even at this incredible speed, to reach our galactic neighbor Andromeda would still take 225 years! If we bump up to a billion times the speed of light, the trip takes less than 3 months, meaning intergalactic colonization becomes possible, and we can commute to any place in our own galaxy. It would take only 10-20 years to reach the edge of the universe itself*, a trip so important that you know some one will attempt it.
But until that time, when we can travel almost instantly to almost anywhere, we must remember that the world is a big place. The local group of the closest stars is a big place. The galaxy is a big place, and it will take a long time for it to become small. Until it does, think of space travel as what travel was like before mass production of the automobile: not very fast.
* Recently (2009), I have learned that the most current estimate for the age of the universe is 13.7 billion years, HOWEVER, the universe has been expanding considerably in all that time such that it is approximately 39 billion lightyears to reach the edge of the VISIBLE universe, and the ACTUAL edge may be another billion or two further out. Still, a journey that lasts less than 100 years (there and back) to discover something so important is almost certain to be attempted._______
Further reading to whet your appetite for knowledge:
Solar System - Mars
Hey baby, what's your sign? (Updated!)
Solar System - Venus