Bad Astronomy. Misconceptions and Misuses Revealed, from Astrology to the Moon Landing 'Hoax'

at an eclipse, it’s even more so for children.

I’ll note here that another common misconception about an eclipse is that the x-rays emitted from the Sun’s corona can damage your eyes. The corona is extremely hot, but so tenuous that the normally bright Sun completely overwhelms it, making it extraordinarily difficult to observe during the daytime.

The corona is so hot that it gives off x-rays. Most folks know that x-rays are dangerous; after all, you have to wear a lead shield when getting an x-ray at the dentist. So many people put these two facts together and assume that it’s the corona that can damage your eyes during an eclipse.

This is wrong. X-rays from any source in the sky cannot penetrate the Earth’s atmosphere, which, for all intents and purposes, absorbs every x-ray photon coming from space. It acts like a shield, protecting us. Even if the atmosphere were not here, the corona is also simply too faint to hurt our eyes. And remember: whether the Sun is eclipsed or not, the corona is still there; it’s just too faint to see. So if it could hurt your eyes during an eclipse, it could do so at any random time. In reality, the corona can’t hurt you.

There are several ways to enjoy an eclipse without risking your eyes. You can use a telescope or binoculars to project the image of the Sun onto a piece of paper or a wall. You can wear very dark goggles, like welders wear; make sure they are rated as #14 so that they are dark enough to be comfortable.

You can also use a solar filter on a telescope or binoculars, but only the kind that mounts in front of the main lens or mirror. This stops most of the light from entering the optics in the first place. Some companies sell filters that go on the eyepieces, which block the amount of light leaving the optics. However, the optics focus all that sunlight right onto that filter, which can heat up a lot. Filters like this have been known to melt or crack. I heard one story of a solar filter that actually exploded! That’s bad enough, but then your eyes are flooded with all that sunlight concentrated by the optics. The lesson: stay clear of such devices.

Also, despite some advice I have seen, do not use unexposed film to block the light. Even as lofty a source as the CNN web site once claimed that it was safe to view an eclipse this way. This is actually a very dangerous way to do it; it lets through less visible light, so your pupils widen. However, it does not block the dangerous wavelengths of light, so that even more damaging light floods your eye. I and several hundred other people flooded CNN with e-mail, and the web site was hastily fixed.

Solar eclipses do not happen very often, and they usually occur over scattered parts of the planet. I have never seen a total solar eclipse, though I’ve seen a dozen or so partial ones. Someday I hope to see a total eclipse myself, but when I do, I’ll be careful.

And I’d better hurry. As is discussed in chapter 7, “The Gravity of the Situation,” the Moon is slowly receding from the Earth. It’s only moving away about 4 centimeters (2 inches) a year, but over time that adds up. As it gets farther away, it appears smaller in the sky. That means eventually it will be too small to completely cover the Sun during a solar eclipse. Instead, we’ll get an annular eclipse, a solar eclipse where the Moon’s size is somewhat smaller than the Sun, and you can see a ring of Sun around the dark disk of the Moon. We get these eclipses now because the Moon’s orbit is elliptical, and if the eclipse occurs when the Moon is at the highest point in its orbit, the eclipse is annular. But, eventually, these will happen all the time. The corona will forever be hidden by the glare of the Sun and solar eclipses will be interesting, but lack the impact they have now. That’s why, in the beginning of this chapter, I said that total solar eclipses are a coincidence of space and time. Given enough time, they won’t happen anymore.

I can’t leave this chapter without busting up one more misconception. It is an extremely common story that Galileo went blind because he observed the Sun through his telescope. I have said this myself, even once on my web site. Andy Young e-mailed me about it and set me straight.

Galileo did indeed go blind. However, it was not due to observing the Sun. Galileo realized rather quickly that looking through his small telescope at the Sun was a quite painful experience. Early on he only observed the Sun just before sunset, when it is much dimmer and safer to see. However, he later used a projection method to view the Sun and observe sunspots. He simply aimed his telescope at the Sun and projected the image onto a piece of paper or a wall, casting a much larger image of the Sun. This method is far easier and produces a large image that is easier to study as well.

Certainly, using a telescope to observe the Sun can indeed cause damage to the eye, since a telescope gathers the sunlight and concentrates it in your eye (much the same way that you can burn a leaf with a magnifying glass). However, this sort of damage occurs very rapidly after solar observation, and Galileo did not go blind until he was in his 70s, decades after his solar observations. There is copious documentation that during the intervening years his eyesight was quite good. Galileo suffered from cataracts and glaucoma later in life, but this was clearly not from his telescopic observations.

Galileo’s observations of sunspots on the Sun caused quite a stir; the Catholic church had considered the Sun to be unblemished and perfect. Together with his observations of Jupiter, Venus, the Moon, and the Milky Way itself, he revolutionized our way of seeing and thinking about science, ourselves, and our universe. Yet we still can’t get simple stories about him correct. Maybe we are the ones who are sometimes blind.

14. The Disaster That Wasn’t: The Great Planetary Alignment of 2000

On May 5, 2000, the Earth was not destroyed.

Perhaps you missed this, since you were busy living, eating, going to work, brushing your teeth, etc. However, in the months before May 5, 2000, a lot of people actually thought the Earth would be destroyed. Instead of the usual culprits of nuclear war, environmental disaster, or the Y2K bug, this particular brand of global destruction was to have been wrought by the universe itself, or, at least, our small part of it.

On that date, at 8:08 Greenwich Mean Time, an “alignment of the planets” was supposed to have caused the Final Reckoning. This Grand Alignment — also called the “Grand Conjunction” by the prophesiers of doom to make it sound more mysterious and somehow more millennial — would throw all manner of forces out of balance, causing huge earthquakes, a possible shift in the Earth’s poles, death, destruction, higher taxes, and so forth. Some even thought it would cause the total annihilation of the Earth itself. The tool of this disaster was to have been the combined gravity of the planets in the solar system.

These people, obviously, were wrong. Some of them were honest and simply mistaken, others were quacks and didn’t know any better, and still others were frauds trying to make money off the misinformed. Nonetheless, they were all wrong, plain and simple.

Of course, there’s a long and not-so-noble history of misinterpreting signs from the sky. Long before studying the skies was a true science, there was astrology. Astrology is the belief that — contrary to every single thing we know about physics, astronomy, and logic — somehow the stars and planets control our lives. The reason astrology came about is not so hard to understand. People’s lives can seem to be out of their control. Capricious weather, luck, and happenstance seem to influence our lives more than we can ourselves. It’s human nature to be curious about the causes of such things, but it’s also human nature to pervert that curiosity into blame. We blame the gods, the stars, the shaman, the politicians, everyone but ourselves or simple bad luck. It’s natural to try to deny our own involvement and wish for some supernatural causation.

There is some connection between what happens in the sky and what happens down here on Earth. Agriculture depends on weather, and weather depends on the Sun. Agriculture also depends on the seasons, and these can be predicted by watching the skies. In winter, the Sun is lower in the sky during the day and it is not up as long. Certain constellations are up when it’s cold, and others when it gets hot. The sky and the Earth seem irrevocably connected. Finding patterns in the sky that seem to have spiritual puppet strings tied to us here on Earth was perhaps inevitable.

Eventually, everything in the sky, from comets to eclipses, was assumed to portend coming events. It may be easy to laugh off such superstitions as the folly of simple people from ancient times. However, even today, firmly into the twenty-first century, we still deal with ancient superstitions that we simply cannot seem to cast off. Just a few months into the new century we had to deal with yet another instance of the shadow of our primitive need to