CompuServe Messages

Joseph, Your explanation of times and orbital mechanics made me think about the circumstances of the fireball I saw; I remember clearly that it shot forward over my head as I walked along Nauset beach on the east side of the "forearm" of Cape Cod with the ocean on the right; in other words, it was moving north. North? That would be more or less perpendicular to the ecliptic, wouldn't it? That seems odd. (I would imagine most meteors move in the same plane as the major planets.) So I decided to look in the journal I kept during those years, which I probably have not read since I wrote it. And it has given me a good lesson in the unreliability of my memory. I was positive the fireball was green, but in fact it was blue. Otherwise I was pretty accurate. Here's what I wrote in my entry for either May 17 or 18, 1981 (from the way I wrote, I can't tell which night it was. But I mention that the moon was full, so I could find out. Then I say): While we were walking on the beach — it was about two in the morning — the ground around us suddenly lit up blue, as if there were a flash of lightning. The light was bright enough, despite the full moon, to cast our shadows before us. We both looked up over our shoulders, but there was no lightning. In fact, there were no clouds. I looked around ahead of us and saw a gigantic fireball moving parallel to the beach straight above us. It had passed right over us as we first looked up. It was a ball of blue flame, about a quarter or a third the apparent width of the full moon, with a trail of blue flame behind it, and a trail of smoke behind the flame. It looked low enough and was bright enough to illuminate its own smoke and I could see ripples in the trail of smoke . . . the smoke trail looked five or six times as wide as the vapor trail of a cruising jet . . . I saw it no more than a fraction of a second, during which time it must have covered ten degrees of arc, when it burned it. It burned out very suddenly, almost without shrinking in size. [I also mention that there was no sound.] From what I've read since I last wrote to you, my supposition that the meteoroid illuminated its trail is wrong; the trail's radiance is apparently the result of excited atoms and ions in the trail itself. And meteors don't burn, as I supposed; they abrade from hitting air molecules. The article in my trusty Encyclopedia Britannica (from which I derive this information) makes this easy to understand by pointing out that a fast rifle bullet may leave the muzzle at 840 m/sec, whereas a slow meteoroid goes about 30 km/sec. Gram for gram, that's 1,250 times as much energy. A fast meteroid, at 60 km/sec, has 5,000 times as much energy. At that speed, hitting air would be sort of like running into a cloud of steel pellets at highway speed, I imagine. — Rob P.S. I doubt there was any connection, but I then mention in my journal that we drove inland and saw the most spectacular display of the aurora borealis I had seen up to that time on Cape Cod (it was normally visible only as a flickering just above the northern horizon, as if a city with electrical problems was located just over the horizon). But that night, it was "like swirling banks of light high in the sky, looking very much like a projection of light inside a flourescent tube whose starter is failing."