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

rem of radiation, which is about the same amount of radiation a person living at sea level accumulates in three years. Over a very long time that level of exposure might indeed be dangerous, but the round-trip to the Moon was only a few days long. Since there weren’t any flares from the Sun, the astronauts’ exposure to radiation was actually within reasonable limits.

Conspiracy theorists also argue that the radiation should have fogged the film used on the lunar missions. However, the film was kept in metal canisters, which again protected it from radiation. Ironically, modern digital cameras no longer use film; they use solid-state electronic detectors, which are sensitive to light. Like any other kind of computer hardware, these detectors are also very sensitive to radiation, and would have been next to useless on the Moon, even if they had been encased in metal. In that case, the older technology actually did a better job than would modern technology.

3. Dust on the Moon’s Surface

The surface of the Moon is dusty. Before any machines landed on the Moon, no one really knew what the actual surface was like. Scientific analysis showed that the Moon’s surface was rocky, and we could even determine the composition of some of the rocks. However, the actual texture of the surface was unknown. It was conjectured by some that the intense sunlight, consisting of ultraviolet light unfiltered by an atmosphere, might break down the rocks into a dust. Micrometeorite hits might do the same. But no one knew for sure if the dust even existed, or how deep it might be.

When the first soft landings were made by Soviet and American probes, it was found that the dust was only a few millimeters to centimeters thick. That was a great relief. No one wanted the Apollo astronauts to sink into a sand trap.

The dust on the Moon is peculiar. It is extraordinarily fine, like well-ground flour. It is also extremely dry, like everything else on the Moon. Unlike the Earth, the Moon has virtually no water at all anywhere on the surface.

Misunderstanding the properties of this dust in an airless environment leads to the breakdown of the next hoax-believer claim, dealing with the landing of the lunar module (or LM), the odd-looking contraption used by the Apollo astronauts to land on the Moon. The LM had four landing legs with disk-shaped feet at the ends, and between them was a powerful rocket used to slow the descent speed as the LM approached the surface.

The conspiracy-theorists claim that the rocket had a thrust of 10,000 pounds, and therefore should have left a substantial crater on the Moon’s surface. Also, that much thrust would blow away all the dust underneath it. How could the lander’s legs and the astronauts’ boots leave imprints in dust? All that dust should be gone!

Both of these claims are wrong. First, the engine was capable of 10,000 pounds of thrust at maximum, but it wasn’t simply a roman candle that burns at full thrust when lit. The engine had a throttle, basically a gas pedal, which could change the amount of thrust generated by the engine. When high over the surface of the Moon, the astronaut flying the lander would throttle the engine for maximum thrust, slowing the descent quickly. However, as the lander slowed, less thrust was needed to support it, so the astronaut would throttle back. By the time the lander touched down, the astronauts had cut the thrust to about 30 percent of maximum, just enough to compensate for the lander’s own weight on the Moon.

Three thousand pounds of thrust still might sound like a lot, but the engine nozzle of the lander was pretty big. The bell was about 54 inches across, giving it an area of about 2,300 square inches. That 3,000 pounds of thrust was spread out over that area, generating a pressure of only about 1.5 pounds per square inch, which is really pretty gentle, less than the pressure of the astronauts’ boots in the dust. That’s why there is no blast crater under the lander; the pressure was too low to carve out a hole.

The second claim about dust near the lander is interesting. Why was there dust so close to the center of the landing site that both the lander legs and the astronauts’ movements left tracks? This defies common sense, which says the dust should have all been blown away. However, our common sense is based on our experience here on Earth, and it pays to remember that the Moon is not the Earth.

Once again, we have to understand that the Moon has no air. Imagine taking a bag of flour and emptying it on your kitchen floor (kids: ask your parents first). Now stand over the flour, stick your face an inch or two above it, and blow as hard as you can.

When you stop coughing and sneezing from having flour blown into your nose, take a look around. You should see flour spread out for a long way on your floor, blown outward by your breath.

However, you’ll see that some flour was carried farther away than your breath alone could have blown it. It’s hard to get a good breeze blowing as far away as your outstretched hand because your breath can really only go a few dozen centimeters before petering out. What carries the dust farther than your breath can go is the air that already exists in the room. You blew air from your lungs, and that air displaced the air in the room, and it was that air that carried the flour farther than your breath alone could push it.

However, on the Moon, there is no air. The thrust of the LM engine was substantial, but it only blew the dust out from directly beneath it. Some of that dust blew for hundreds of meters, but, contrary to our experience here on Earth, the dust just outside the immediate area where the exhaust plume touched down was largely left alone. Plenty of dust was left there in which to leave footprints. In reality, a little more dust got blown around than that because the dust blown around directly by the engine can smack into other particles of dust, moving them also. So the “hole” in the dust was bigger than the burn area of the rocket, but not substantially so. Incidentally, in the tapes of the Apollo 11 landing you can hear Buzz Aldrin commenting that they were “picking up some dust” from the engines as they neared the surface. Neil Armstrong, who piloted the LM, complained that the moving dust made it hard for him to figure out how fast they were moving across the surface.

Some hoax-believers also claim that the dust could not keep footprints because it has no water in it, and you need something wet to keep it compacted. This is nonsense. Flour is incredibly dry, yet you can easily leave a footprint in it. This claim is bizarre, and again I am dumbfounded as to why someone would put it forward when it is so trivially easy to prove wrong by experiment. In this case, at least, common sense leads you the right way.

4. The Temperature of the Lunar Surface

Related to the dust problem is that of the Moon’s temperature. The Apollo missions were made during the day on the Moon. Measurements of the Moon’s surface show that the temperature can get as high as 120 °C, hot enough to boil water! Hoax-proponents point out that the astronauts could not have lived through such fierce heat.

In one sense they are correct: that much heat would have killed the astronauts. However, the astronauts were never in that much heat.

The Moon spins on its axis once every 27 days or so. That means that a lunar day is four weeks long, with two weeks of sunlight and two weeks of darkness. Without an atmosphere to distribute the heat from the incoming sunlight, the daylit side of the Moon does get tremendously hot, and the dark side gets very cold, as cold as ?120 °C.

However, the surface doesn’t heat up the instant the sunlight touches it. At sunrise the sunlight hits the Moon at a very low angle, and it does not efficiently heat it. It takes days for the lunar surface to get to its high temperature, much as the worst heat of the day on Earth is reached after the Sun reaches its peak. NASA engineers, knowing this, planned the missions to take place at local morning, so that the Sun was low in the sky where they landed. You can see this in every photograph taken from the surface; the shadows are long, indicating the Sun was low in the sky.

As it happens, the spacesuits were designed to keep the astronauts cool, but not because of the outside heat. In a vacuum, it’s very difficult to get rid of the astronauts’ own body heat. An astronaut inside an insulated suit generates a lot of heat, and that heat needs to get dumped somehow. The suits needed ingenious methods to cool the astronauts. One way was to pipe cool water through tubes sewn into their undergarments. The water would warm up, picking up their waste heat, then flow into the backpacks where the heat could be dumped away into space.

So there really was a problem with temperature, but it was internal, not external. Another hoax claim, frozen in its tracks.

Incidentally, the dust on the surface of the Moon is a terrible conductor of heat. Powdery materials usually are. Although the dust was actually warmed by sunlight, it wasn’t able to transfer that heat well to the astronauts through their boots. Oddly, even though the surface of the Moon gets to 120 °C at noon, the dust is only that hot for