Exposing PseudoAstronomy

October 5, 2011

Playing Hide-and-Seek with the Apollo Landers


Introduction

This post is less about “pseudoastronomy” and more about what you (or anyone) with an internet connection can do with the amazing pictures taken by NASA’s Lunar Reconnaissance Orbiter. Though I suppose it’s also related to the Apollo Moon hoax in that we finally have a camera in orbit that’s capable of seeing the Apollo landers.

The Instrument

The Lunar Reconnaissance Orbiter (LRO) spacecraft has been in orbit of the moon for nearly three years. It has a suite of instruments onboard, though the one we want for this exercise is called the Lunar Reconnaissance Orbiter Camera (LROC). This camera actually has two “lenses” on it — a wide-angle camera (WAC) and a narrow-angle camera (NAC).

The spacecraft is in an orbit that, with the field of view of the cameras, allows WAC images to have a pixel scale of 100 meters, and the NAC has a pixel scale of about 50 cm (0.5 meters, or about 20 inches). And that’s just cool.

So we’re using LRO’s LROC’s NAC. Lots of a.c.r.o.n.y.m.s. Each NAC image is about 2.5 km wide and generally about 50 km long – a tiny fraction of the surface of the moon.

What to Do

You could use the LROC image search feature and find the Apollo landing coordinates from Wikipedia or some other source, put them into the search, and go searching for the Apollo sites that way.

You could cheat a bit and use this website’s list of NAC images with the Apollo landing sites in them (that’s what I did). Then you can use the LROC image search and search for that exact image and click on it. Or, you can directly go to the URL http://wms.lroc.asu.edu/lroc/view_lroc/LRO-L-LROC-2-EDR-V1.0/M113853974RE and replace that last string of letters and numbers (M113853974RE in the case here, which is for the Apollo 16 landing site) with the image ID.

Then, search! You can use the Flash-based tool that the LROC team has set up on that page to zoom in and out and search for the landing site, or you can download a TIFF image (generally around 20-50 MB) from the link towards the top (“Download CDR PTIF”). Sometimes using the information and image on the site with the list helps you to find it more easily.

But while you’re searching, you’ll find a lot of other interesting features. You could find the Apollo 17 “Challenger” descent stage along with the astronaut tracks (story about that on the LROC site here). And if you end up liking treasure-hunting on the moon, you may find Moon Zoo a citizen science project, of interest.

When identifying the NAC images to look through, one thing to pay attention to is the “incidence angle” or “solar altitude” which tells you what the shadows are going to be like. You may think that it’s best to see these when the sun is directly overhead (solar altitude is 90°, or incidence angle is 0°). But, this isn’t actually the case, You want longer shadows so that the features are easier to see. Incidence angles closer to 60-80° or so are generally best (solar altitude 10-30°).

But don’t take my word for it — try looking at the same landing site under an 80° incidence versus a 10° incidence angle. While the craters are much harder to see and the landing sites look more like brightness features rather than “3-D” because of the lack of shadows, you’ll see things like bright crater ejecta and dark crater ejecta that the lower sun angles made invisible!

Final Thoughts

Maybe it’s just me, but I actually find this kind of thing fun (I spent an hour looking for Apollo 15 last night in 5 different lighting conditions). It also gives you a nice perspective on the relative sizes of things — not necessarily that the Apollo hardware was “small,” but really how BIG the moon is, and how much we have left to explore.

If the solar system were reduced in size such that the sun were a grapefruit (about 10 cm), Earth would be located about 11 meters away. Humans have traveled a mere 2.8 cm, or about 1 inch, into the solar system.

I also find it absolutely amazing that in this day and age, there are still people out there who don’t think we ever landed people on the moon.

P.S. Please remember my comments policy. I consider anything related to UFOs to be off-topic for this post.

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June 17, 2011

A Fancy Sign Does Not Good Science Make


Introduction

As my first post since my hiatus to finish my degree, I thought I’d bring up a timely topic. Over on the Moon Zoo forums, one of our most active volunteers and forum moderators, a woman who goes by the name of Jules, posted about her time at the Times Cheltenham Science Festival.

From the Festival, Jules posted about her own outreach with Moon Zoo (and those other zoos …). She also took a photo of a particular sign:

Moon Sign at Cheltenham Science Festival

Moon Sign at Cheltenham Science Festival - Original credit, Jules W.

You can click the image to enlarge it. I strongly suggest reading it before moving on.

Let’s Look at the Text

The particular offensive paragraph is the fourth:

“As you have noticed the Moon goes through a number of phases, from full Moon, though to new Moon and back to full Moon. This is because as the Moon orbits, the sunlight that makes it visible can be blocked by the Earth. This means that the amount of the Moon that is illuminated depends upon where the Moon is along its orbit.”

Interesting. I would ask why you can see the sun and moon in the sky at the same time if Earth’s shadow is blocking light, causing the Moon’s phases.

You can also think about a lunar eclipse, such as the one that was visible just this week from most of Europe, Africa, and Asia.

What’s Wrong with This

If you haven’t caught on yet, this is not why we have phases of the moon. The moon orbits Earth approximately once a month. As it orbits, one half is lit by the sun, and the other half is in its own shadow, just as Earth is always half-lit by the sun and half in its own shadow for night. Since the moon keeps one face always looking at Earth, it is slowly rotating relative to the sun and so each point on its surface goes through about two weeks of daylight and two weeks of night.

For a really cool movie illustrating this made by an amazing graphic artist, educator, and scientist, check out this link (22 MB, MOV format).

In other words, this sign is wrong. Blatantly wrong. Clearly wrong. Any little amount of thought put in would indicate that this is wrong (why do we see the moon in any phase other than full at the same time as the sun? we shouldn’t if Earth’s shadow is what causes the phases …).

And yet this sign looks nice, is shiny, has several corporate sponsors, and is presented at a large science festival.

Two More Things

The poster also lists a distance to the Moon as 384,000 km. This is correct. Until Jules pointed out to me that the sign claims this is the distance between the Moon and Sun (which is 149,600,000 km ± 384,000). The 384,000 km is the distance between Earth and the Moon.

A final incorrect statement has to do with the third paragraph which states that the moon having the same side facing Earth has been “very useful as astronomers have been able to map the surface of the Moon using telescopes.” This doesn’t really make sense. I suppose one may be able to claim that it would take us twice as long to map the Moon if we saw the whole thing, but then the nice part would be we’d be able to map the whole thing. We had to wait for the first Soviet flyby to return photographs of the lunar far side before we could even begin to guess what it was like.

Final Thoughts

This gets to the heart of two of the main reasons I do this blog. (1) It shows that all because you have a big fancy sign does not mean that you are right. People have to be ever-vigilant and questioning or they risk falling for something like this. (2) I think people learn better by examining misconceptions / mistakes that they make or others have made. The sign is clearly wrong, but you may not have known why it was wrong — it may have just sounded weird. So now with the actual explanation for phases, you can contrast that with the sign’s explanation which can make it easier to remember.

On a related theme, this sign actually reminds me of a sign I saw in a science museum a few years ago. It was talking about the force of a car crash and how much destructive power a 60 mph (100 kph) car crash has. And then the museum decided to throw in another line about how, “But, according to the Heisenberg Uncertainty Principle, if conditions had been a little different the accident may not have happened at all!”

Yes, that was a science museum. Using a fallacious appeal to quantum mechanics.

Keep a lookout, folks, these things are everywhere. To distort a phrase, the price of knowledge is eternal vigilance against pseudoscience.

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