when Han says that line. Maybe he is wincing at his pilot’s braggadocio; I choose to think Obi Wan knows his units.
If you go far from the lights of a city on a clear night and wait long enough, chances are you’ll see a shooting star. The proper name for it is a meteor. Of course, meteors aren’t stars at all. They are tiny bits of gravel or dust that have evaporated off the surface of comets during their long voyages around the Sun. Some are the shrapnel from collisions between asteroids. Most of them are very small; an average one is about the size of a grain of sand.
While they are out in space, these specks are called meteoroids. They orbit the Sun as the Earth does, and sometimes their paths cross ours. When one does, the little piece of flotsam enters our atmosphere, and the tremendous pressure generated by its travel through our air causes it to heat up tremendously, so hot that it glows. That glow is what we call a meteor. If it impacts the ground, it’s called a meteorite.
These three names cause a lot of confusion. A meteoroid glows as a meteor when it moves through the air, and it becomes a meteorite when it hits the ground. I got into an argument once with a friend about what to call meteors during various parts of their travel. I said they are meteorites when they hit the ground. He asked, “What if they hit a house and stop on the second floor?” I countered that the house is in direct contact with the Earth, so it’s still a meteorite. He rebutted by asking, “What if it hit an airplane and stopped?”
I had to scratch my head over that one. Is it a meteorite when the plane lands? What if the plane crashes? At this point we decided we were being silly, and decided to just go outside and look for meteors. That may have saved our friendship.
Anyway, meteors start off in space and then fall to the Earth. They appear dramatically, flashing into our view, and burn out suddenly as they descend through the atmosphere toward the ground, sometimes leaving a long trail of glowing ash behind them. They start off bright, then fade away.
Enter bad astronomy. I was reading a major metropolitan newspaper one day and was amused when it referred to a Russian official’s “meteoric rise” in the political structure of that country. Of course, the reporter meant that the official appeared out of nowhere and made a quick, brilliant rise to the top of his heap. The
I had the misfortune one morning to wake up to the radio playing the song “Dream Weaver.” I’ll admit I used to love that song when I was a kid, but as a friend of mine likes to say, “We are not responsible for songs we liked when we were 15 years old.” Anyway, as the tired, hackneyed verses went on, one in particular caught my ear: “Fly me away to the bright side of the moon, and meet me on the other side.”
Of course, there is a bright side of the Moon, and you can go to it. But if you sit still, you can only be there for two weeks, max. The bright side, and therefore the dark side as well, is not a fixed place, but appears to move as the Moon rotates.
Seen from the surface of the Earth, the Moon does not appear to rotate. It seems to show the same face to us all the time. Actually it does spin; it’s just that it spins once for every time it goes around the Earth. Its rotation teams up with its revolution in such a way that it always shows that one face to us. We call that face the near side of the Moon. The other side, the one we never see, is called the far side. The far side of the Moon has only been seen by probes or by astronauts who have actually orbited the Moon. Since it’s remote and not well known, the far side of the Moon has become synonymous with something terribly far away or unexplored.
The problem is, people confuse the
Like the Earth, the Moon spins. The Earth spins once every 24 hours, so that someone standing on its surface sees the Sun go up and down once a day. As seen from outside the Earth, that person is on the dark side of the Earth when he or she is on the half that is facing away from the Sun. But the dark side is not a permanent feature! Wait a few hours, and the Earth spins enough to bring that person back into the sunlight. He or she is now on the bright side of the Earth. No part of the Earth is on the dark side forever.
The same goes for the Moon, except its day is 29 of our Earthdays long. Someone on the Moon will see the sun set two weeks after it rises! Since half the Moon is in sunlight and half in darkness, there
You can see that the dark side of the Moon is simply just the
One of the best selling music albums of all time is Pink Floyd’s
Incidentally, at the end of that album there is a quiet voiceover: “There is no dark side of the moon. As a matter of fact, it’s all dark.” In a sense that line is correct: the Moon is actually very dark, only reflecting less than 10 percent of the sunlight that hits it. That makes it about as dark as slate! The reason it looks so bright is that it is in full sunlight, and that means there’s a lot of light hitting it. Ironically, even though six Apollo missions landed on the near side of the Moon, they only explored the tiniest fraction of the surface. In essence, even the
Now, to be honest, there may be a part of the Moon that’s always dark. Near the poles there are deep craters with raised rims around them. From that region the Sun is always near the horizon, just like at the poles on Earth. Since the craters on the Moon can be deep, the Sun may always be hidden by the rim of the crater. Sunlight never reaches the bottom of such craters! There is tantalizing evidence of ice at the bottom of such craters, untouched by the warming rays of the Sun. If it’s true, there are two major implications. One is that the ice can be used by lunar colonists for air and water, negating the need to carry it along with them from Earth. That saves a vast amount of money, fuel, and effort.
The other implication is that the phrase “dark side of the Moon” actually has a limited truth to it — as far as the dark crater bottoms go! Maybe I need to start a “Not-So-Bad Astronomy” web site.
Sometimes the advertising executives we discussed earlier aren’t satisfied with being “light-years ahead” of their competitors. They come up with a product so revolutionary that it leaves the others in the dust. It’s more than light-years ahead, it’s a whole new product. How to describe it?
Sometimes they say it’s a “quantum leap” ahead of the others. But how big a leap is that, really?
The nature of matter has been a mystery for thousands of years (and really, it still is). Contrary to our modern bias that ancient people were not as smart as we are now, the ancient Greeks theorized about the existence of atoms. The thinker Democritus deduced that if you split a rock in half, then do it again, and again, and again, eventually you might come to a point where you simply cannot split it any more. That tiniest part he called an atom, meaning “indivisible.”
This knowledge was interesting but of no fundamental meaning until thousands of years later. The advent of better technology let us investigate these tiny atoms. At first, it was thought that the atom looked like a solid little ball, but experiments soon showed that there were two separate parts — a nucleus in the middle made of particles called protons and neutrons, and an outer part containing particles called electrons. One model had the atom looking like a miniature solar system, with the nucleus acting like the Sun and the electrons orbiting like little planets.
This model sparked a flurry of science-fiction stories in which the solar system itself was just an atom in a greater universe of matter. This concept was really just a model, not designed to be a true picture of reality. Nevertheless, the idea still persists today in much of the public’s mind.
However, the model turned out to be incorrect. At the very beginning of the twentieth century, a new physics was born. It was called quantum mechanics, and it postulated a horde of weird
