Archive for Moon

Supermoon Surgery

Posted in Biographical, The Universe and Stuff with tags , , , , , , , on August 11, 2014 by telescoper

I have a busy day today (including my Annual Appraisal) to kick off a very busy week dominated by the release of this years A-level results and consequent admissions business, so I’ll just post a quickie though one which is at least fairly topical.

Last night (10th August) I took a (not very good) picture of the Moon with my phone:

 

supermoon

This is a so-called “supermoon“, a not particularly rare phenomenon which takes place when there is a Full Moon that coincides with the Moon being at the point of its orbit which is closest to the Earth, i.e. its perigee. A much better name is “Perigee Full Moon”, but that somehow doesn’t seem to have caught on in the popular media. The Moon orbits the Earth in an ellipse rather than a circle and at its closest approach it is about 14% closer than at its furthest (apogee). It therefore looks about 14% bigger and about 30% brighter during a Perigee Full Moon than during an Apogee Full Moon.

The Moon was certainly looking very bright when I took the picture last night, at least compared to a few minutes later when it disappeared behind a supercloud.

The Moon’s proximity to Earth during this Full Moon does have a noticeable effect on terrestrial tides, but not a particularly strong one; certainly not enough to trigger the end of the world. Actually, the tides have an amplitude just a few inches higher than average during a Perigee Full Moon. In any case roughly one in 14 Full Moons is a supermoon so it’s actually quite a common event, and as far as I’m aware the world didn’t come to an end during the last one or the one before that or the one before that or…

Anyway, all this supermoon malarkey reminded me of something that happened about 15 years ago,  just after I had moved to Nottingham to take up the position of Professor of Astrophysics at the University of Nottingham. I was sitting in my office, working – blogs hadn’t been invented then – when the phone rang and the voice at the other end said May I speak to Professor Coles please? When I replied that I was he, the caller went on to explain that he was a surgeon who worked at Queen’s Medical Centre, a hospital located right next to the University of Nottingham, with teaching staff working for the University.

It turned out that news of the setting up of the new Astronomy group there had made it into the University newsletter which my caller had seen. He asked if I had a few moments to answer a question about astrophysics which had been bothering him for some time and which he had just been discussing with some of his colleagues.  I said yes, and he asked: Does the Moon rotate?

I paused a bit, thinking how best to explain, and he went on to clarify his point, which was that if the Moon always has the same face towards the Earth does that mean it’s not rotating?

Understanding his question, I went on to explain that, yes, the Moon does rotate and that the reason it always shows the same face to the Earth (more-or-less, ignoring libration) is that the period of its rotation is the same as the Moon’s orbital period around the Earth. I also explained how to demonstrate this with two coffee mugs, moving one in a circle around the other and rotating the outer one so as to keep the handle pointing towards the central mug. Moreover, I explained the physics of this phenomenon, which is called tidal locking, and pointed out other examples in astrophysics.

After this spiel the caller said that was all very interesting but he had to go  now. Assuming I had bored him, as I fear I tend to do rather a lot, I apologized for going on about it for too long. He said no he wasn’t at all bored by the detail I had put in, he found it all absolutely fascinating. The reason for him needing to go was that he had to go back to tell the answer to the colleagues he had been discussing it with  just before phoning me.  They were all  in the operating theatre,  standing around a patient lying on the operating table, waiting  for him to return and complete the operation he had left in order to make the call…

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The Moon Doctor

Posted in Biographical, The Universe and Stuff with tags , , on November 4, 2011 by telescoper

I  worked all the way through my lunch break getting stuff ready for a short tripette that I have to make next week. My regular post-prandial blogpost  is consequently a bit later than usual, and also a bit shorter.

Anyway, the little orbital dynamics question I posted a couple of days ago, which seems to have attracted quite a number of responses, also reminded me of something that happened about 12 years ago,  just after I had moved to Nottingham to take up the position of Professor of Astrophysics at the University of Nottingham. I was sitting in my office, working – blogs hadn’t been invented then – when the phone rang and the voice at the other end said May I speak to Professor Coles please? When I replied that I was he, the caller went on to explain that he was a surgeon who worked at Queen’s Medical Centre, a hospital located right next to the University of Nottingham, with teaching staff working for the University.

It turned out that news of the setting up of the new Astronomy group there had made it into the University newsletter which my caller had seen. He asked if I had a few moments to answer a question about astrophysics which had been bothering him for some time and which he had just been discussing with some of his colleagues.  I said yes, and he asked: Does the Moon rotate?

I paused a bit, thinking how best to explain, and he went on to clarify his point, which was that if the Moon always has the same face towards the Earth does that mean it’s not rotating.

Understanding his question, I went on to explain that, yes, the Moon does rotate and that the reason it always shows the same face to the Earth (more-or-less, ignoring libration) is that the period of its rotation is the same as the Moon’s orbital period around the Earth. I also explained how to demonstrate this with two coffee mugs, moving one in a circle around the other and rotating the outer one so as to keep the handle pointing towards the central mug. Moreover, I explained the physics of this phenomenon, which is called tidal locking, and pointed out other examples in astrophysics.

After this spiel the caller said that was all very interesting but he had to go  now. Assuming I had bored him, as I fear I tend to do rather a lot, I apologized for going on about it for too long. He said no he wasn’t at all bored by the detail I had put in, he found it all absolutely fascinating. The reason for him needing to go was that he had to go back to tell the answer to the colleagues he had been discussing it with  just before phoning me.  They were all  in the operating theatre,  standing around a patient lying on the operating table, waiting  for him to return and complete the operation he had left in order to make the call…

Back to the Drawing Board

Posted in Art, Education, The Universe and Stuff with tags , , , , , , , , , on August 30, 2011 by telescoper

I came across a press release this morning which contains the following

More should be done to encourage students to use their drawing skills in science education, researchers at The University of Nottingham say.

In a paper being published in Science this week, academics say that although producing visualisations is key to scientific thinking, pupils are often not encouraged to create their own drawings to develop and demonstrate their understanding.

In the paper the authors, led by Dr Shaaron Ainsworth in the University’s School of Psychology and Learning Sciences Research Institute, said: “Scientists do not use words only but rely on diagrams, graphs, videos, photographs and other images to make discoveries, explain findings, and excite public interest.

In the light of this I thought it would be topical to post an updated version of an old piece I wrote on the theme of sketching. This is quite a strange subject for me to have picked pick because drawing is something I’m completely useless at, but I hope you’ll bear with me and hopefully it will make some sense in the end. I always thought that drawing was an important and neglected aspect of education, but I hadn’t until today any solid research to back it up!

-0-

What  spurred me on to think about this subject was the exhibit I was  involved with for the  Architecture Biennale in Venice as part of a project called Beyond Entropy organized by the Architectural Association School of Architecture. In the course of researching this project I came across this image of the Moon as drawn by Galileo

This led to an interesting discussion about the role of drawings like this in science. Of course  the use of sketches for the scientific representation of images has been superseded by photographic techniques, initially using film and more recently by digital techniques. The advantage of these methods is that they are quicker and also more “objective”. However, there are still many amateur astronomers who make drawings of the Moon as well as objects such as Jupiter and Saturn (which Galileo also drew). Moreover there are other fields in which experienced practioners continue to use pencil drawings in preference to photographic techniques. Archaeology provides many good examples, e.g.

The reason sketching still has a role in such fields is not that it can compete with photography for accuracy or objectivity but that there’s something about the process of sketching that engages the sketcher’s brain in a  way that’s very different from taking a photograph. The connection between eye, brain and hand seems to involve a cognitive element that is extremely useful in interpreting notes at a later date. In fact it’s probably their very subjectivity that makes them useful.  A thicker stroke of the pencil, or deliberately enhanced shading, or leaving out seemingly irrelevant detail, can help pick out  features that seem to the observer to be of particular significance. Months later when you’re trying to write up what you saw from your notes, those deliberate interventions against objectivity will take you back to what you  saw with your mind, not just with your eyes.

It doesn’t even matter whether or not you can draw well. The point isn’t so much to explain to other people what you’ve seen, but to record your own interaction with the object you’ve sketched in a way that allows you to preserve something more than a surface recollection.

You might think this is an unscientific thing to do, but I don’t think it is. The scientific process involves an interplay between objective reality and theoretical interpretation and drawing can be a useful part of this discourse. It’s as if the pencil allows the observer to interact with what is observed, forming a closer bond and probably a deeper level of understanding patterns and textures. I’m not saying it replaces a purely passive recording method like photography, but it can definitely help it.

I have not a shred of psychological evidence to back this up, but I’d also assert that sketching is very good for the learning process too.  Nowadays we tend to give out handouts of diagrams involved in physics, whether they relate to the design of apparatus or the geometrical configuration of a physical system. There’s a reason for doing this – they take a long time to draw and there’s a likelihood students will make mistakes copying them down. However, I’ve always  found that the only way to really take in what a diagram is saying is to try to draw it again myself. Even if the level of draftsmanship is worse, the level of understanding is undoubtedly better.Merely looking at someone else’s representation of something won’t give your brain as a good a feeling for what it is trying to say  as you would get if you tried to draw it yourself.

Perhaps what happens is that simply looking at a diagram only involves the connection between eye and brain. Drawing a copy requires also the connection between brain and hand. Maybe  this additional connection brings in additional levels of brain functionality. Sketching iinvolves your brain in an interaction that is different from merely looking.

The problem with excessive use of handouts – and this applies not only to figures  but also to lecture notes – is that they turn teaching into a very passive process. Taking notes in your own hand, and supplementing them with your own sketches – however scribbly and incomprehensible they may appear to other people – is  a much more active way to learn than collecting a stack of printed notes and meticulously accurate diagrams. And if it was good enough for Galileo, it should good enough for most of us!

Scale

Posted in The Universe and Stuff with tags , , , , , on January 31, 2011 by telescoper

A number of people drew my attention to this today. It’s definitely worth passing on to those of you who haven’t seen it already. Have a look at this  blog post too!


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Insignificance

Posted in The Universe and Stuff with tags , , , , , , , on January 4, 2011 by telescoper

I’m told that there was a partial eclipse of the Sun visible from the UK this morning, although it was so cloudy here in Cardiff that I wouldn’t have seen anything even if I had bothered to get up in time to observe it. For more details of the event and pictures from people who managed to see it, see here. There’s also a nice article on the BBC website. The BBC are coordinating three days of programmes alongside a host of other events called Stargazing Live presumably timed to coincide with this morning’s eclipse. It’s taking a chance to do live broadcasts about astronomy given the British weather, but I hope they are successful in generating interest especially among the young.

As a spectacle a partial solar eclipse is pretty exciting – as long as it’s not cloudy – but even a full view of one can’t really be compared with the awesome event that is a total eclipse. I’m lucky enough to have observed one and I can tell you it was truly awe-inspiring.

If you think about it, though, it’s a very strange thing that such a thing is possible at all. In a total eclipse, the Moon passes between the Earth and the Sun in such a way that it exactly covers the Solar disk. In order for this to happen the apparent angular size of the Moon (as seen from Earth) has to be almost exactly the same as that of the Sun (as seen from Earth). This involves a strange coincidence: the Moon is small (about 1740 km in radius) but very close to the Earth in astronomical terms (about 400,000 km away). The Sun, on the other hand, is both enormously large (radius 700,000 km) and enormously distant (approx. 150,000,000 km).  The ratio of radius to distance from Earth of these objects is almost identical at the point of a a total eclipse, so the apparent disk of the Moon almost exactly fits over that of the Sun. Why is this so?

The simple answer is that it is just a coincidence. There seems no particular physical reason why the geometry of the Earth-Moon-Sun system should have turned out this way. Moreover, the system is not static. The tides raised by the Moon on the Earth lead to frictional heating and a loss of orbital energy. The Moon’s orbit  is therefore moving slowly outwards from the Earth. I’m not going to tell you exactly how quickly this happens, as it is one of the questions I set my students in the module Astrophysical Concepts I’ll be starting in a few weeks, but eventually the Earth-Moon distance will be too large for total eclipses of the Sun by the Moon to be possible on Earth, although partial and annular eclipses may still be possible.

It seems therefore that we just happen to be living at the right place at the right time to see total eclipses. Perhaps there are other inhabited moonless planets whose inhabitants will never see one. Future inhabitants of Earth will have to content themselves with watching eclipse clips on Youtube.

Things may be more complicated than this though. I’ve heard it argued that the existence of a moon reasonably close to the Earth may have helped the evolution of terrestrial life. The argument – as far as I understand it – is that life presumably began in the oceans, then amphibious forms evolved in tidal margins of some sort wherein conditions favoured both aquatic and land-dwelling creatures. Only then did life fully emerge from the seas and begin to live on land. If it is the case that the existence of significant tides is necessary for life to complete the transition from oceans to solid ground, then maybe the Moon played a key role in the evolution of dinosaurs, mammals, and even ourselves.

I’m not sure I’m convinced of this argument because, although the Moon is the dominant source of the Earth’s tides, it is not overwhelmingly so. The effect of the Sun is also considerable, only a factor of three smaller than the Moon. So maybe the Sun could have done the job on its own. I don’t know.

That’s not really the point of this post, however. What I wanted to comment on is that astronomers basically don’t question the interpretation of the occurence of total eclipses as simply a coincidence. Eclipses just are. There are no doubt many other planets where they aren’t. We’re special in that we live somewhere where something apparently unlikely happens. But this isn’t important because eclipses aren’t really all that significant in cosmic terms, other than that the law of physics allow them.

On the other hand astronomers (and many other people) do make a big deal of the fact that life exists in the Universe. Given what  we know about fundamental physics and biology – which admittedly isn’t very much – this also seems unlikely. Perhaps there are many other worlds without life, so the Earth is special once again. Others argue that the existence of life is so unlikely that special provision must have been made to make it possible.

Before I find myself falling into the black hole marked “Anthropic Principle” let me just say that I don’t see the existence of life (including human life) as being of any greater significance than that of a total eclipse. Both phenomena are (subjectively) interesting to humans, both are contingent on particular circumstances, and both will no doubt cease to occur at some point in perhaps not-too-distant the future. Neither tells us much about the true nature of the Universe.

Let’s face it. We’re just not significant.


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The Sketch Process

Posted in Art, Education, The Universe and Stuff with tags , , , , , , , , , on August 25, 2010 by telescoper

It’s pouring with rain so, rather than set off home and get drenched, I thought I’d spend a few minutes on the blog and hope that the deluge dies down before I leave. Knowing my luck it will probably get worse.

Anyway, I thought I’d put together a short item on the theme of sketching. This is quite a strange subject for me to pick because drawing is something I’m completely useless at, but I hope you’ll bear with me and hopefully it will make some sense in the end.

What  spurred me on to think about it was the exhibit I’ve been involved with for the forthcoming Architecture Biennale in Venice as part of a project called Beyond Entropy organized by the Architectural Association School of Architecture. Unfortunately, although I’d originally planned to attend I can’t be there for the opening Symposium, but I hope it turns out to be as successful event as it promises to be!

Anyway, in the course of this project I came across this image of the Moon as drawn by Galileo

This led to an interesting discussion about the role of drawings like this in science. Of course  the use of sketches for the scientific representation of images has been superseded by photographic techniques, initially using film and more recently by digital techniques. The advantage of these methods is that they are quicker and also more “objective”. However, there are still many amateur astronomers who make drawings of the Moon as well as objects such as Jupiter and Saturn (which Galileo also drew). Moreover there are other fields in which experienced practioners continue to use pencil drawings in preference to photographic techniques. Archaeology provides many good examples, e.g.

The reason sketching still has a role in such fields is not that it can compete with photography for accuracy or objectivity but that there’s something about the process of sketching that engages the sketcher’s brain in a  way that’s very different from taking a photograph. The connection between eye, brain and hand seems to involve a cognitive element that is extremely useful in interpreting notes at a later date. In fact it’s probably their very subjectivity that makes them useful.  A thicker stroke of the pencil, or deliberately enhanced shading, or leaving out seemingly irrelevant detail, can help pick out  features that seem to the observer to be of particular significance. Months later when you’re trying to write up what you saw from your notes, those deliberate interventions against objectivity will take you back to what you  saw with your mind, not just with your eyes.

It doesn’t even matter whether or not you can draw well. The point isn’t so much to explain to other people what you’ve seen, but to record your own interaction with the object you’ve sketched in a way that allows you to preserve something more than a surface recollection.

You might think this is an unscientific thing to do, but I don’t think it is. The scientific process involves an interplay between objective reality and theoretical interpretation and drawing can be a useful part of this discourse. It’s as if the pencil allows the observer to interact with what is observed, forming a closer bond and probably a deeper level of understanding patterns and textures. I’m not saying it replaces a purely passive recording method like photography, but it can definitely help it.

I have not a shred of psychological evidence to back this up, but I’d also assert that sketching is very good for the learning process too.  Nowadays we tend to give out handouts of diagrams involved in physics, whether they relate to the design of apparatus or the geometrical configuration of a physical system. There’s a reason for doing this – they take a long time to draw and there’s a likelihood students will make mistakes copying them down. However, I’ve always  found that the only way to really take in what a diagram is saying is to try to draw it again myself. Even if the level of draftsmanship is worse, the level of understanding is undoubtedly better.Merely looking at someone else’s representation of something won’t give your brain as a good a feeling for what it is trying to say  as you would get if you tried to draw it yourself.

Perhaps what happens is that simply looking at a diagram only involves the connection between eye and brain. Drawing a copy requires also the connection between brain and hand. Maybe  this additional connection brings in additional levels of brain functionality. Sketching iinvolves your brain in an interaction that is different from merely looking.

The problem with excessive use of handouts – and this applies not only to figures  but also to lecture notes – is that they turn teaching into a very passive process. Taking notes in your own hand, and supplementing them with your own sketches – however scribbly and incomprehensible they may appear to other people – is  a much more active way to learn than collecting a stack of printed notes and meticulously accurate diagrams. And if it was good enough for Galileo, it should good enough for most of us!

Now it’s stopped raining so I’m off home!


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Crater 308

Posted in Art, The Universe and Stuff with tags , , , , , on August 1, 2010 by telescoper

I haven’t got time to post much today – WordPress was down earlier when I had a bit of time and now I’m going to watch the highlights of England’s Test victory against Pakistan in the cricket today, which they achieved by bowling out their opponents for only 80 runs in the second innings.

Nevertheless, as a quick filler, I thought it would be nice to show this wonderful image of the crater Daedalus, formerly known as Crater 308, which is located on the far side of the Moon. Not the dark side, by the way, the far side of the Moon gets just as much sunlight as the near side!
This is one of the images I’ve been working on as part of the project Beyond Entropy for a forthcoming exhibit at the Venice Biennale of Architecture which opens at the end of this month. I won’t say too much about the exhibit I’m involved with, except that it explores the way higher-dimensional information can be recorded in surfaces of lower dimension, like a kind of architectural holographic principle. I was particularly struck by the way the pattern of cratering on the Moon yields information about its formation history, which is why I went looking for dramatic examples. This – taken during the Apollo 11 mission- is my favourite image of all those I’ve looked at. I love the complexy topography, its textural contrasts and the way the shadows play across it.

Daedalus is an impact crater that formed about 3.75 to 3.2 bn years ago. It’s about 93km across. The crater looks relatively fresh; showing sharp-ish-looking rims all around with sequences of wonderfully-preserved terraces down onto a pock-marked, flat floor consisting of numerous craterlets and a central peak divided up into two to three well-defined hills. You can also see the effect of more recent impacts in and around it.

Talking of impact, I wonder if I can get this project into our REF submission?