Myths and Eclipses

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Two Carnivals

Two science-based blog carnivals have gone online recently. At Pharyngula the Creation Museum Carnival has just gone live. I appreciate the freedom of speech issue. If someone wants to spend millions of dollars fighting against science that it their right, but there’s no need to agree with or even respect dishonesty.

More cheerful is the Carnival of Space, hosted by Universe Today, which has a collection of links on Space Science and Astronomy from various weblogs.

Sex and Patrick Moore

I haven’t commented on this with the flood of other recent comments because I wanted to take time to think this over. If you haven’t seen the news recently Sky at Night presenter Patrick Moore has complained about banal television programmes and then blamed the fall in quality TV on women becoming bosses.

It’s a big disappointment. It would be an exaggeration to say Astronomy IS Patrick Moore in the UK, but he is an enormous influence. It’s likely that if he hadn’t been the presenter of Sky at Night for fifty years that the programme would have been repurposed like Tomorrow’s World. So I’ve been taking time trying to make sense of why he’d say such a thing and it’s difficult. I’m not eager to believe that he is so badly wrong. What makes it more difficult there aren’t really any mitigating factors and that he’s almost right.

The Antikythera Mechanism and the Birth of Science?

[Cross-posted to Revise & Dissent]

We had a talk recently at Leicester from Mike Edmunds, the professor at Cardiff who’s been leading the research into the Antikythera Mechanism. I plan to write more about that in the future, but one of the many highlights of the talk was that the mechanism has implications for how Greeks thought about Natural Philosophy, the precursor to Science.

The ancient Greek view of the world is strange. Sometimes you can be stunned by the skill of their observations, like when you see the Antikythera Mechanism. Other times their beliefs appear to make no sense at all. For instance the Athenians closed their silver mines in the winter – to allow the silver to grow back. Something that’s puzzled me is how people who were not stupid could think such a thing. Surely someone would have noticed the rock was as it was at the end of last season? One possible answer is that until the invention of devices like the Antikythera Mechanism there was no alternative.

13 things that don’t make sense

According to New Scientist, here are 13 things that don’t make sense. How many can you explain?

1. The placebo effect
2. The horizon problem
3. Ultra-energetic cosmic rays
4. Belfast homeopathy results
5. Dark matter
6. Viking’s methane
7. Tetraneutrons
8. The Pioneer anomaly
9. Dark energy
10. The Kuiper cliff
11. The Wow signal
12. Not-so-constant constants
13. Cold fusion

The Orientation of Roman Camps

I’m working on a problem which means I have to work out if a given set of astronomical alignments are significant. I have a possible solution, so now I’m testing it one someone else’s data. What I’m doing is treating the data as a Binomial Distribution. I have a few aims with this technique. First it has to give reliable results. Next I have to understand it. Thirdly and equally importantly I have to be able to describe it so that archaeologists and historians can follow the argument. If they can’t then it gets pointless writing. My analysis may not be correct, so I’m putting it up here and submitting that to Carnival of Mathematics and Tangled Bank to see if people think the maths is wrong. I’m also putting it up on Revise and Dissent where it will get submitted to the History Carnival and Four Stone Hearth to see if it’s intelligible and sounds reasonable to Historians and Archaeologists.

Roman Camps and their Orientations reconsidered.

There is currently a debate in the pages of the Oxford Journal of Archaeology on the orientations of Roman camps and forts. Richardson (2005:514-426) argues that the orientation of these camps is non-random and relied on some form of astronomical observation. He presents data which he argues supports his case. Recently Peterson (2007:103-108) has argued this relies on a flawed use of the Chi-squared test. I accept Peterson’s findings that Chi-squared is not a useful method. However examining the camps as a binomial distribution would be feasible and would make explicit the archaeological and astronomical assumptions made in the argument.

What is a Roman Camp?

The sites being examined are Roman camps and forts in England. One of the major advantages that the Roman army had over the native opposition when occupying new territory was their organisation. The Roman army was effectively a professional army taking on amateurs. Their camps reflect this organisation. Typically their early camps a ditch surrounded by a bank in a playing-card shape. They followed a set design. The rationale for this was if there were attacked by surprise equipment and people would be in the same place at each camp, minimising the effects of the surprise.

A Roman fort at Wallsend. Photo from Google Earth

The ancient sources give some detail on how to lay out a Roman camp. The main gate should face the enemy, or the line of advance (Vegetius 1.23, Hyginus 56). The rear gate should be on the higher ground to aid surveillance. Sites overlooked by hills were considered a bad idea, as were sites near woodlands which would allow the enemy to sneak up on the camp. The basic layout of the camp could be set up quickly by surveyors using gromae, surveying tools for laying out lines at right angles. Hyginus (chapter 12) states that you set up your groma at the junction at the centre of the camp and lay out your roads to the gates from there.

This would appear to be an efficient method of laying out a camp. Were observations to orientate the camp also part of the method? It doesn’t seem necessary, but Richardson (415,422-23) provides quotes from ancient sources which suggest this is plausible hypothesis in some circumstances.

The Star of Bethlehem

[Cross-posted to Revise & Dissent]

Did Giotto get the birth of Christ right after all?

When people hear that I study ancient astronomy, a question I tend to get asked every so often is “What was the Star of Bethlehem?” There’s a few exciting explanations, so mine tends to disappoint. I’m pretty much of the same opinion as Martin when it comes to explaining Biblical miracles. There’s no independent evidence that many of these happened as described. There are however lots of strange events recorded in the ancient literature, and many honest misunderstandings. A lot of questioners assume the star must have existed, and therefore it’s simply a matter of explaining what it was. If this were a star of Apollo or Ueuecoyotl then fewer people would be convinced the star existed. Another problem is that just because you can spot a pattern it doesn’t mean it’s meaningful. I can see a duck-shaped cloud out of the window. I can’t believe it’s a divine sign that God is fed up of people eating turkey. Similarly, while there are a lot of astronomical events you could say were a star, they don’t really withstand much scrutiny. However, I am open to the idea that I need to change my mind, because I have read an explanation that might work.

Liquid Water on Mars

NASA has announced the discovery of liquid water on Mars thanks to MGS images.

The clue is that the continual imaging by the MGS has enabled the team to track changes in the surface over time. The really exciting thing is that the team think that this shows evidence of material being moved by water today. The traces are light streaks in gulleys.

Photo by NASA

There are a few reasons why the scientists are arguing for the existence of water. One is the colour of these streaks. Usually when the dust gets disturbed on Mars, the surface gets darker. This is seen in the tracks the Mars rovers make, the trenches Viking made and the scars of impacts from space. These streaks are a lot lighter. Why the streaks are lighter is unknown, but there are couple of possibilities.

The Antikythera Mechanism

A paper on the Mechanism appears in tomorrow’s Nature. In brief what it is these days is a rather unimpressive looking lump of heavily corroded metal. I have a photo of it somewhere, but it’s a very bad blurry photo which doesn’t do justice to its lumpy unimpressiveness. Fortunately Wikipedia has this much better photo.

The Antikythera Mechanism in the National Museum, Athens. Photo from Wikipedia.

The reason why it’s news is that there’s been a lot of painstaking work to try and see beyond the corrosion, and its proven spectacularly successful. The mechanism has been examined using X-ray tomography, which is where X-rays are used to build up a cross-section of a subject slice by slice without physically pulling the subject apart. The results are confirming that Greek technology could be staggeringly sophisticated.

Transit of Mercury

Mercury is passing in front of the Sun as I type. You can follow the Mercury transit until 0100 GMT (UT) via the Big Bear Solar Observatory‘s webcam. Here’s the start. You’re looking for the black dot that shifts.

Below is a version I’ve re-coloured, but hopefully you can see where the dot has moved.

The reason the live image appears black and white is that the Big Bear Observatory is only looking at light in the H-Alpha wavelength, which means that it’s all one shade. This limitation that allows them to pick out features on the Sun better. Observations of this transit were used as a test of Einstein’s theory of Relativity.