Lunar Research

Moon books and films
About a year ago I did a couple of posts on my old blog (here and here) showing some of the books and DVDs I had the pleasure of “researching” for my Pseudoscience and Science Fiction book. Now I’m working on the follow-up. It’s not really a sequel, except that it’s for the same publisher and involves a similar mix of science fiction and real science (though no pseudoscience this time).

The general subject will be easy enough to guess from the “research” materials pictured above. My book is going to have a Unique Selling Point … but I don’t want to divulge that until its finished!

Photographing the Moon

Closeup of Vallis Alpes region

About six months ago I got interested in photographing the Moon, and I’ve been posting some of the results on Facebook. Mostly I’ve used a simple telescope webcam, which can produce high-resolution images of relatively localized areas such as the one above (showing the lunar north pole at the top and the Alpine Valley at the bottom, with the craters Aristoteles and Eudoxus to the east of it). Then a few days ago I posted a wider field of view using a DSLR on the same telescope, and Rhodri Evans asked how that compared with using the DSLR with its own lens.

That prompted me to try a few tests last night (with the Moon at first quarter). For anyone who may have just stumbled across this blog, I should stress that I know almost nothing about astrophotography, so please don’t take this as “best practice” advice. On the other hand, it does give an idea what a beginner can achieve with bottom-of-the-market equipment (I’ll give details of the hardware and software at the end of the post).

To start with, here is a picture of the Moon taken through the 75-300 mm lens that came with the camera. This uses the highest zoom (300 mm) at f/16, 1/250 second exposure, ISO-800 (settings visually optimized using Live View). It’s the sort of picture anyone with a DSLR could take.

Moon with DSLR

Now here’s a single frame taken with the same camera attached to the telescope (i.e. effectively using the telescope as a long telephoto lens). My telescope has a focal length of 600 mm, but I used a 2x Barlow lens as well, which doubled the focal length to 1200 mm (i.e. four times the camera’s own lens). The telescope aperture is 120 mm, which I guess makes it f/10, and again I used a 1/250 exposure and ISO-800.

Moon with DSLR and telescope

I also took a short movie (20 seconds, 500 frames) using the same settings, and stacked the result into a single image using Autostakkert. The result is a definite improvement (I tried the same trick with the camera-only shot, but in that case it made things worse).

Stacked image with DSLR and telescope

Here’s a side-by-side comparison of those three photos. The telescope is an improvement on the camera alone, but stacking is what really works the magic.

Comparison of Moon photos

As I said at the start, I normally use a small astronomical webcam to capture images, because it’s so easy to use. Optically this is identical to attaching the DSLR to the telescope (aperture 120 mm, focal length 1200mm with the 2x Barlow lens), but the field of view is much smaller because the sensor array is tiny (4.8 mm rather than 22.3 mm). For the same reason the image drifts across the screen more quickly (I don’t have a tracking mount), so I only have time to grab a 10-second video, or 300 frames at 30 fps. Nevertheless the results – such as the example at the top of this post – are impressive after stacking in Autostakkert.

Here is a side-by-side comparison of that picture with the same area seen in the single-frame DSLR+telescope and DSLR-alone images:

Comparison of Moon detail

For reference, my telescope is a Skywatcher Startravel-120 refractor on an equatorial mount, which cost me £389. There are plenty of other good telescopes available around this price. The webcam is a ZWO ASI120MC, which at around £170 is pretty much the cheapest astronomical camera on the market. Similarly my DSLR is from the bottom of the market – a Canon EOS 100D, which I got complete with two zoom lenses for just £379.

The ZWO camera came with two pieces of software – SharpCap for capturing videos and Autostakkert for stacking – but they’re both freely available online (here and here respectively). In the examples shown here, I used GIMP (also free) to crop, rotate and contrast-enhance the images.

Space-Age Nostalgia

Here are two items I bought in W. H. Smith’s recently. The first is a special (and very expensive) issue of the BBC Sky at Night magazine about the Apollo missions, and the second (a much better deal at the same price) is a repackaging of a 2008 Discovery Channel series about NASA spaceflights from Mercury to the Shuttle, together with another magazine. Presumably both items were put out for the Christmas gift market – mainly as a nostalgic treat for people of my generation, I guess, although it would be nice to think some youngsters are interested in the subject too.

I learned quite a lot from both items, particularly about the earlier and later missions. Although I was always interested in space, it was only in a vague, general way up until the Apollo 8 mission. That happened shortly after my 11th birthday, and it was the first one I really got drawn into – in the sense that I knew the astronauts’ names and avidly followed every little phase of the mission. This really intense awareness continued through Apollos 9, 10, 11, 12 and 13, but then started to get murky again after that point.

Not for the obvious reason, though. You might think, “well, of course, everyone lost interest in the later Apollo missions” – but that wasn’t it at all. I’ve got files of newspaper clippings I carefully cut out about Apollos 14 to 17, as well as Skylab and the Apollo-Soyuz test project. I’ve got some photos and fact sheets about Skylab that I sent off to NASA for (as well as another batch about Apollo from a few years earlier). But I never absorbed the huge amounts of information about those later missions that I did for Apollo 8-13 – for the simple reason that the information just wasn’t there to be absorbed.

In the early 70s Britain only had three TV channels, and they were all in the “general entertainment” category. There were no purely factual channels, no 24-hour news channels … and of course no internet. The TV gave blanket coverage to things like Apollo 8 and Apollo 11, but later missions had to compete for airtime with soap operas, sports, comedy shows and the like. Key space events were still covered – live – but they had a frustrating tendency to happen when you were at school, or otherwise indisposed. People didn’t have video recorders in those days.

So it’s an over-simplification to say that “everyone lost interest in the later Apollo missions”. It was the mainstream media that lost interest – and in the 1970s, that was the only kind of media there was. We’re so much luckier today!