The Bad Astronomer

Every January, professional astronomers converge on a medium-sized convention center for the annual meeting of the American Astronomical Society. This year, the good city of Atlanta (not so medium sized) was host to this event, and seeing as I had gone to graduate school in Atlanta, I was looking forward not only to catching up on all the cutting-edge astronomy that would be presented at the convention, but also to re-connecting with old friends.

During the opening night reception, which invariably features reams of graduate students descending on the small buffet lines, I caught sight of one of my favorite people, Phil Plait, a.k.a. the Bad Astronomer.

Not that Phil is actually a bad astronomer. He's a professor at Sonoma State University, and although I've never been there, teaching astronomy in Sonoma sounds like a pretty good deal to me. But aside from his academic duties, Phil provides a monumental service to the space-science community, in the form of his website, essays, and book, all called "Bad Astronomy."

In these works, Phil takes a good-humored but rigorously scientific look at all different kinds of conspiracy theories and pseudo-science that seem to work their way into the public consciousness. As an astronomer working in public outreach, I often get questions from people who want to know why NASA faked the Moon landings (how else can you explain why there are no stars in the sky, or why the astronaut's shadows aren't all parallel?) or whether the Earth is at risk of being ripped apart by gravity when all the planets line up on the same side of the Sun. And honestly, I find myself at a bit of loss. To simply dismiss these questions as stupid makes me seem at best an arrogant scientist, and at worst, part of the "conspiracy" myself. So I fire up Phil's website, www.badastronomy.com.

What I really love about Phil's stuff is that he does the math. Take as an example the concern caused by planetary alignments, when some or all of the planets line up on one side of the Earth. Every few years, when a particularly good alignment is coming up, doom-sayers start coming out of the woodwork, claiming that the increased gravity or tidal forces will cause earthquakes and tsunamis, or even rip the Earth apart.

Is this possible? To me, the simplest counter-argument is that this must have happened in the past many, many times, and we're still here. Set nine planets orbiting the Sun, and every couple hundred or thousand years, they're bound to line up to some degree. Doesn't seem to have destroyed the Solar System yet. But if that doesn't seem qualitative enough to you, check out Phil's reasoning: he calculates (and the math is all there on his website), that the combined gravitational pull of all the planets is slightly less than 2% of the Moon's gravitational pull on us.

Well, is there a chance that even that amount of variation will affect the Earth? This is highly unlikely, as Phil points out, as the Moon's gravitational pull naturally changes much more than that in the course of a single month:

"Think of it this way: the Moon orbits the Earth in an ellipse, which means that sometimes in its orbit it is closer to the Earth than others. At perigee, or closest approach, it is about 363,000 kilometers away, and at apogee, or farthest point, it is about 405,000 kilometers away. If you use these numbers like we did above, you see that the Moon's own gravitational effect on the Earth fluctuates by about 25% every orbit! The Moon orbits the Earth in about a month, incidentally, so it goes from apogee to perigee every two weeks. So every 14 days we see a change in gravitational effects from the Moon more than 10 times greater than all the other planets combined!"

There's lots of other amusing debunkings to be found too. Supposedly, draining sinks are affected by the Coriolis Force, a rotational force caused by the Earth spinning on its axis. This force is indeed responsible for weather patterns being different in the two hemispheres, most obviously in the fact that low pressure systems rotate in a counter-clockwise direction in the Northern hemisphere, and clockwise in the South. Sinks are, in effect, small low-pressure systems, but they are much too small to feel this effect, and the water drains out of them far too rapidly. The direction that water spins as it drains away is much more effected by the shape of the sink basin or what motions in the water have been introduced ahead of time by, say, washing the dishes.

Other favorites of mine include the legend that you can only balance an egg on its end during the vernal equinox (where the heck did that one come from?). Phil has pictures of himself in his Bad Astronomy Book balancing eggs on astronomically unimportant days. There's also a movie and TV review section, which allows for a perusal of all your favorite sci-fi shows to find out what's wrong with their science. I, for one, am sure that all the scientists in the world will never convince people that explosions don't make any sound in space. It's a lost cause

On the serious side, Phil's website is the only place I've been able to find a point-by-point rebuttal to the strange notion that NASA faked the Moon landings. A few years ago, when Fox came out with its special, "Conspiracy Theory: Did We Land On the Moon?'', I started to get questions from the public about whether the Moon landings had been faked. At first, I just sort of stared blankly at the person asking the question, unsure how to proceed. Did we fake the Moon landings? Uh, no. But admittedly, I had no good replies to the accusations the conspiracy buffs were making, and I hate feeling stupid. Phil goes down each of the points in clarity and detail.

Some of the pro-conspiracy arguments are just plain ludicrous: why can't you see any stars in the photos the astronauts took from the Moon, even though the sky was completely black? Really for the same reason that you can't see stars when you take a picture of someone at night, and use a flash. It's a matter of exposure time. Yes, the airless sky on the Moon is black even in the daytime, and if you were standing there, you'd be able to see stars. But when you're taking a picture of your fellow astronaut in the bright, hard sunshine, you need to set your exposure time low enough for the picture not to be totally whited out. That's too short of an exposure to pick up the faint, but present, stars in the sky.

Why does the flag that the astronauts deployed on the Moon look like it's waving, when there's no air to wave in? The flags the astronauts used were hung from a horizontal rod that telescoped out from the vertical flagpole. During Apollo 11, the astronauts couldn't get the horizontal support rod to extend completely, so the flag looked a little rippled. During the later landings, the astronauts found they liked this "flag waving" effect, and didn't deploy the rod to its full extent on purpose (Phil found that last part in a NASA spaceflight website, but that probably won't do much to convince the conspiracy fans).

But some of the other faked-moon-landing claims are a bit more harmful, as they purport to use science to "prove" the existence of this conspiracy. Not surprisingly, they don't bother to actually do any of the calculations, or find out how the science really worked. And that just makes me mad.

Take the argument that there should have been a blast crater left by the retrorockets that the astronauts used to land on the Moon. There didn't seem to be one in the pictures of the lunar modules on the surface of the Moon -a detail that NASA obviously forgot to fake. Remember that the Moon's gravity is only one sixth that of Earth's, so in fact, it doesn't take all that much thrust to slow down your descent. In actuality, the astronauts used about 3000 pounds of thrust to land the lunar module. The rocket's nozzle was about 54 inches across, or about 2300 square inches in area. Divide the thrust by the area, and you've got about 1.3 pounds per square inch, hardly enough to carve out a blast crater.

I could go on, but I think you'll have more fun exploring Phil's site on your own. He's also recently put out a book that has many highlights from the website, plus a lot more. It's called "Bad Astronomy," and it's available from any number of on-line booksellers. Phil fights the good fight against foes ranging from simple ignorance, to deliberate deception. And that makes him a very good astronomer indeed.