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

astronomer, imagine for a moment you aren’t so that you can then again imagine that you are). You have some nifty idea for an observation, and you decide you want to use Hubble for it. What do you do?

First, you’d better be sure you really need Hubble. Remember, for every astronomer trying to get time on Hubble, there are five others who are also vying for it, which means that right at the start you only have a one-in-six chance of getting your proposal accepted. That, in turn, means that the committee of astronomers that chooses who gets to use Hubble can be very picky. If your project can be done from the ground, you get rejected. If your project takes up too much time with only a marginal return in science learned, you get rejected. If you ask to do something that’s already been done, you get rejected. If you ask to do something someone else is asking to do, and the other proposal is better, you get rejected.

Get the picture? It also takes days or weeks to prepare a proposal, time that you could spend working on other projects or trying to get other grants. You might use up a lot of precious time preparing your proposal only to have it roundly rejected.

But suppose you are lucky and your idea is accepted. Congratulations! Now you move to the next step. You have to painstakingly detail every single thing you want Hubble to do, including the initial pointing to your target, every exposure, every filter, every little bump and wiggle needed to get the observations you want. This detailing may also take several days or weeks, using complicated software guaranteed to give you a headache.

But finally you finish and submit the final proposal. Congratulations again!

Now you wait.

It may take up to a year or so to make those observations after the scheduling goes through. When you do, you are faced with many gigabytes of data, and you need a lot of software and experience to analyze them. It may take months or even years to figure everything out. With luck and perseverance, you may actually get a paper in the astronomical journals out of all this.

Now, think for a moment about all that work. All that analysis before and after the observations costs time and money, neither of which an astronomer has in copious amounts. For someone on a research grant time is money, and grants are very difficult to come by. Applying for HST time is a big gamble. You hope to get accepted, and then you hope the data are good enough to further your research, so you can get even more grants. I don’t mean to put so much emphasis on money as a means unto itself, but without it, it’s pretty hard to do research. In a sense, your future career as a scientist depends on your ability to get good data; you’re staking your scientific reputation on your research. That Hubble data, once you’ve published it in an astronomical journal, is your lifeline.

Now imagine that the instant you get your data, some other astronomer has access to it, too. This other astronomer isn’t as scrupulous and nice as you are. He or she also has experience with Hubble, knows just how to analyze your data, and might publish before you do! All that work, all that effort and time, and you get scooped with your own data.

That’s why the data are held as proprietary for a year. That year gives the astronomer time to figure out what to do with the data and how best to analyze them. It’s only fair to you, who devoted so much of your life to getting the data, to let you have a chance to look at them before anyone else.

So there’s no real secret involved. At the end of the proprietary period, ready or not, the data become public. Far from being anything shady on the part of NASA, keeping the data secret for a year is actually the best way astronomers have come up with to further the cause of science in a fair manner. It can be an agonizing wait when you know some good data won’t be available for a year, but it’s worth it.

Hubble Shoots the Moon

Hubble is more than just a telescope with a camera stuck onto it. It’s a telescope with several cameras stuck onto it. Each instrument has a specific task. Some take ultraviolet images, others take infrared.

Some take spectra by breaking the light from an object into individual colors. Each camera is a delicate, expensive piece of machinery. Some of these instruments are very sensitive to light. They can actually be damaged if too much light hits them. Anyone who has ever had a roommate turn on a light in the middle of the night can sympathize with that.

This sensitivity has caused yet another myth about Hubble, that it cannot take images of the Moon. As the myth goes, the Moon is far too bright to be observed by Hubble without damaging these delicate instruments.

This turns out not to be the case.

It is true that the operators of Hubble need to be careful with subjecting the instruments to “an overlight condition.” For example, there is a very strict “solar avoidance zone,” a large area of sky around the Sun where Hubble is forbidden to look. The Sun is too bright, and if Hubble points too closely to it, the Sun would do all sorts of damage. That law is very stringently applied and has only been bent once, to observe the planet Venus.

However, this doesn’t really apply to the Moon, which is far less bright than the Sun. While it’s true that some of Hubble’s cameras are very sensitive to light, they can simply be shut off during a lunar observation, allowing other, less sensitive cameras to be used. Still, many people have this mindset that you cannot look at bright objects, including the Moon. It’s funny, because Hubble routinely observes the Earth and, from Hubble’s vantage, the Earth is far brighter than the Moon.

The reason Hubble observes the Earth is nothing nefarious. Sometimes the great observatory is turned toward the Earth to take long exposures that help calibrate the cameras onboard. This allows astronomers to understand how the cameras behave. Hubble cannot easily track fast-moving objects, and the ground moves underneath Hubble at a clip of eight kilometers (five miles) per second. It makes a lousy spy satellite. The images are all streaked from the movement of the objects. I’ve seen some of these images, and you can clearly spot houses and trees that look like long, gray streaks. You don’t have to bother shutting your window to protect your privacy. All Hubble sees of you is a long, blurry worm.

So, if Hubble can take images of the Earth, it certainly can take images of the Moon. The belief that the Moon is too bright is unfounded.

That said, why don’t we see routine Hubble observations of the Moon?

For one thing, we already have really good images of the Moon from the Apollo missions and the Clementine lunar orbiter, better than Hubble can take. But there’s more.

Here’s where I sheepishly must admit to propagating my own little piece of bad astronomy. I’m commonly asked this question. I also used to say that Hubble can’t take images of the Moon. It’s not that the Moon is too bright, it’s that it moves too fast. Hubble must be maneuverable enough to track nearby planets as they orbit the Sun, but the Moon moves across the sky much faster than even the fastest planet. There’s no way, I would say, that it could track the Moon.

I was partially wrong in saying that. True, Hubble cannot track the Moon. But it doesn’t have to track it. The Moon is bright. When you take an image of a bright object, you can take a shorter exposure. In fact, Hubble could take an image of the Moon with such a short exposure time that it would look as if the Moon were not moving at all. It’s just like taking a picture out the window of a moving car. If you take a long exposure the trees will look blurred due to your motion. But if you snap a fast one the trees will look sharp and motionless. They don’t have time to blur.

In 1999 just such an image of the Moon was taken by Hubble. The astronomers were clever. They put Hubble into “ambush mode,” pointing it to a place where they knew the Moon would be and waiting for it to move into view. When it did, they took the image using a fast exposure. The results were pretty neat. They got nice pictures of the Moon, although not really any better than we had from orbiters. The principal goal of the observations was to get spectra of the lunar surface to help astronomers understand the properties of all the planets, and the images were an added bonus. So Hubble can indeed shoot the Moon, and did in the waning years of the twentieth century.

Ironically, while many people think that the Moon is too bright to observe with Hubble, it’s the very brightness that allows Hubble to observe it! It’s bright enough to let us take short snapshots of it without blurring.

Turning the Crank

Unfortunately, the Moon issue won’t die. Some people really want to see conspiracies and cover-ups everywhere they look, even when there are none to be had. One such person is Richard Hoagland, who maintains a