Category: Science

Science, usually research I have done or topics on which I have lectured

May 13 2012

The sky at night!

And so after 10 days, I finally had a chance to play with my new telescope on Friday night! Optical astronomy requires at least a few gaps in the clouds but last night at 8pm it was completely clear – I was hopping up and down like an overactive child waiting for the sun to go down (scheduled for about 8:40pm) and simultaneously cursing the slightest wisp of cloud. It should be clear that I’m a bit new to this, so what I write shouldn’t be seen as in the slightest bit authorative.

Kindly folk at @newburyastro had suggested Venus and Saturn as targets for my first adventure into the night. Useful advice because, as a relative beginner I had little idea what I was going to see, or in fact when I was going to see it. Venus become visible at about 9:20pm towards the now-set sun, it turns out that pointing the ‘scope with the finderscope is much easier than the rather more hazardous enterprise of finding the sun without (something I describe here). In the eyepiece Venus appears as a small, bright crescent.

It was a breezy evening which meant that my view jiggled about a bit, it also jiggled about a bit whenever I touched the telescope. However I did manage a picture of Venus taken on my Canon 400D at prime focus. This is an uncropped view, and it’s upside down.

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Venus (1/50 second, ISO200)

 

Mars made an appearance a little later at about 9:35pm along with a bright star which I believe is Regulus. This enabled me to get my telescope to work out how it was orientated meaning it could track to objects on demand and also tell me what I was looking at (very handy for a novice). My picture of Mars is a little uninspiring, I’ve zoomed in here as far as possible, in Mars’ favour it does look red and it isn’t a simple point.

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Mars (cropped, 1/3 second, ISO200)

 

By now more and more stars were coming out, so I thought I’d try out my piggyback mount. This image is taken with a 10mm lens (i.e. really wide angle) with the telescope simply used as a camera mount pointed at Polaris, it’s a 30s exposure.

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The Northern circumpolar region (Canon 400D, 10mm, 30s ISO200, f/4)

 

 

It took a while to get this because I had auto-focus on and the camera couldn’t find anything to focus on so wouldn’t fire – switching off auto-focus and focusing to infinity manually resolved this. It was at this point I wished I could remember how to switch the display on the back of my camera off because it was really bright, and remember which button was which without being able to see it. The thing that surprised me about this is that there are rather more stars than I could see with my naked eye and some of them are quite strongly coloured. I feel I should go about identifying the stars in my picture.

At this point I thought I’d give Saturn a go, I must admit I thought it was hidden behind buildings and trees from my position in the back garden but I punched it into the telescope handset and it pointed me into the side of the conservatory, so I picked up the telescope and moved it one metre to the right, peered through the finderscope and tweaked my direction a bit and… the planet with ears popped into view!! This was really exciting! I only have one eyepiece for my telescope and it’s quite low magnification but through the eyepiece I could see my target was not a point, and it was not round – it was shaped like a flying saucer and there were slight gaps either side of the central body. Having marvelled at this for a bit I thought I’d try for another photograph:

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Saturn (cropped, 1/4s, ISO200)

 

It’s not the best picture of Saturn taken last night but it is my picture!

The moon hadn’t risen before I went to bed, so when I spotted this morning I rushed out for a photo.

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The Moon 9(1/500s, ISO400)

 

I’ve not done any astrophotography before these (apart from my shots of the sun, and a couple of shots at the moon through a conventional lens). I guess the thing I carried over from that was that the moon is a rock in full sun, so you need to set your exposure times accordingly, the same is true for Mars and Venus so I suspect I should be using shorter exposure times for them to which will also reduce any motion blur.

My first night of viewing has highlighted a need to have a better grip of how to work your camera, plan what you want to look at in advance and, as with an SLR camera, a telescope is simply a gateway drug for further accessory purchase.

May 08 2012

First light–images of the sun

I’ve had my new telescope (a Celestron NexStar 5SE) nearly a week now and so far I have images of miscellaneous chimney pots, arials, pigeons, and… the sun. Only the last of these can be considered fair astronomical game, I’ve had two goes at it so far. I tending to the view that my telescope blog posts shall be like a lab book of what I have done rather than a guide to others, except to perhaps highlight those things that are obvious to experienced astronomers but not to the novice.

The first rule about looking at the sun through a telescope is:

Do it carefully with the appropriate solar filter in place

Seriously, be really careful pointing telescopes at the sun – mine is a small one and it concentrates light by a factor of 300, looking near the sun with the naked eye is bad – imagine x300 more light!

I bought a sheet of Baader AstroSolar solar filter film at the same time as I got my telescope, this comes in the form of a thin A4 sheet of material that looks like foil. It has an optical density of 5, meaning it lets 0.001% of the incident light through. There are detailed instructions supplied with the AstroSolar film for constructing your own mount for the material, or you could go and buy a proper mounted filter (here).

The aim of the filter mount is to hold the filter film without stressing it and in a manner convenient to attach it to the front of your telescope. I should, perhaps, have used the “thick card” that the instructions recommended rather than the corrugated cardboard from the box the telescope came in, and it turns out double-sided carpet tape is really exceedingly sticky. However, the result shown in the image below is functional and I have included a built-in “filter shield” of my own invention for storage. Behind the two cardboard rings sandwiching the filter is a cardboard tube which fits neatly over the optical tube.

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Celestron NexStar 5SE with homemade solar filter from Baader AstroSolar

The next challenge is pointing the telescope at the sun, this turns out to be pretty tricky because with a solar filter in place the only thing in the sky that you can see is the sun, the field of view on my telescope is approximately the size of the moon, you can’t navigate by distinctive clouds and you can’t look through your finderscope unless it is also solar filtered. I’d read that you should move the telescope until the shadow of its tube is a circle – I tried doing this on the ground (minimising the area rather than trying to get a circle). At one point I thought I’d found the sun but from later observations I suspect I was staring at an internal reflection. But easier, since my telescope has a non-magnifying StarPointer finderscope I cast the shadow of that onto a piece of card until it looked round (see image below). The second time I tried this, I got a “hole-in-one” – the sun in my field of view at the first attempt! I could improve this by slotting a disk with a small hole in the middle into the finderscope and aligning until a bright spot appeared in the middle.

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Shadow of the Celestron Star Pointer, used to align the telescope to the sun

 I have to say that seeing the sun through my telescope for the first time was as exciting as digging up potatoes, that’s to say really exciting!

I then moved to trying to photograph my target, I did this using a Canon 400D SLR. The camera is attached by a T-mount to the back of the telescope, in place of the eyepiece. This means that the telescope is replacing the camera lens,s known as “prime focus photography”. Two configurations are possible: with and without the “Star Diagonal” in place. The field of view through the Star Diagonal is smaller, and dimmer than the direct connection however the viewing position is more comfortable and there is less risk of the camera falling off! The direct connection gives a correctly oriented view through the camera, whilst the Star Diagonal gives an upside-down view. The focus position for the eyepiece and the two different camera configurations are all different. The camera is triggered using a remote release cable.

My first attempt is shown below, this is a 1/640s at ISO200 taken without the StarDiagonal:

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Image of the sun, Canon 400D ISO200, 1/640s exposure

Below are crops to the two visible clusters of sunspots:

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Sunspot detail

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Sunspot detail

These look a little less distinct than they did through the eyepiece which may have been because I forgot to enable “mirror lockup”. The second time around I did a bit better, this is taken at ISO100 with a 1/125s exposure again without the StarDiagonal:

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Image of the sun, Canon 400D ISO100, 1/125s exposure

With a detail of the sunspots:

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Sunspot detail

I have a nice set of solar features, sunspots with dark umbra and a paler penumbra, limb darkening (the sun appears less bright towards its edges) and plages (related to faculae) which are bright spots, these are pretty difficult to see. The image below is a crop of the sunspot area to the right hand side of the image above with some contrast enhancement (I boosted the shadows using Picasa) which just about shows the plages:

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Solar photo showing plages

Next time I should probably set the white balance to something other than “auto”, and experiment a bit with exposure times to see if I can get the plages showing up a little better. A Barlow lens would give me some magnification of the sunspots… and so the spending on accessories begins!

Apr 07 2012

Board of Longitude

It’s been a while since I did a data driven blog post, so here I am with one on the “Board of Longitude”. The board was established by act of parliament in 1714 with a headline prize of £20,000 to anyone who discovered a method to determine the longitude at sea to within 30 nautical miles. The members of the Board also had discretion to make smaller awards of up to £2,000 in support of proposals which they thought had merit. The Board was finally wound up in 1828, 114 years after its formation.

The latitude is your location in the North-South direction between the equator and either of the earth’s poles, it is easily determined by the position of the sun or stars above the horizon, and we shall speak no more of it here.

The longitude is the second piece of information required to specify ones position on the surface of the earth and is a measure your location East-West relative to the Greenwich meridian. The earth turns at a fixed rate and as it does the sun appears to move through the sky. You can use this behaviour to fix a local noon time: the time at which the sun reaches the highest point in the sky. If, when you measure your local noon, you can also determine what time it is at some reference point Greenwich, for example, then you can find your longitude from the difference between the two times.

The threshold for the highest Longitude award amounts to knowing the time at Greenwich to within 2 minutes, wherever you are in the world, and however you got there. This was a serious restriction at the time, because a journey to anywhere in the world could have taken months of voyaging at sea with its concomitant vibrations and extremes of temperature, pressure and humidity all of which have serious implications for precision timekeeping devices.

The Board of Longitude intertwines with various of the people whose biographies I’ve read, and surveying efforts taking place during the 18th and 19th centuries. It made a walk on appearance in Tim Harford’s Adapt, which I’ve just read, as an early example of prizes being offered to solve scientific problems.

Below I present data on the awards made by the Board during its existence from 1714 to 1828. The data I have used is from “Britain’s Board of Longitude: The Finances, 1714-1828” By Derek Howse1 which I reached via The Board of Longitude Project based at the Royal Museums at Greenwich. The chart below shows the cumulative total of the awards made by the Board (blue diamonds), awards made to John Harrison who won the central prize of the original Board (black triangles) and the dates of Acts of Parliament relating to the Board (red squares). Values are presented as at the time they were awarded, the modern equivalent values are debatable but the original £20,000 award is said to have been worth between £1million and £3.5million in modern terms, so a rule of thumb would be to multiple by 100 to get approximate modern values.

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Although established in 1714, the Board made no reward until 1737 and until 1765 made the great majority of awards to John Harrison for his work on clocks; clockmakers Thomas Earnshaw (1800, 1805), Thomas Mudge (1777,1793) and John Arnold (father and son 1771-1805) also received significant sums from the Board.

A second area of awards was in the “lunar” method of determining the longitude which uses the positions of stars relative to the moon to determine time and hence longitude. The widow of Tobias Mayer received the largest award, £3,000, for work in this area. The list of awardees contains a number of famous European mathematicians including Leonhard Euler, Friedrich Bessel, and Johann Bernoulli.

After 1763 the Board started to branch out, having been mandated by parliament to prepare and print almanacs containing astronomical information. In the twilight of its years the Board gained responsibility for awards relating to the discovery of the North-West passage (a sea route from the Atlantic to the Pacific via the north of Canada), the second largest recipient of awards for the whole period were the crews of the Hecla and Griper of £5000 in 1820 for reaching 110oW within the Arctic Circle, pursuing this goal.

The story of the Board of Longitude is often presented as a battle between the Board and John Harrison for the “big prize” but these data highlight a longer and more subtle existence with Harrison receiving support over an extended period and the Board going on to undertake a range of other activities.

References

1. “Britain’s Board of Longitude: The Finances, 1714-1828” By Derek Howse, The Mariner’s Mirror, Vol. 84(4), November 1998, 400-417. (pdf) Sadly the article notes that Derek Howse died after the preparation of this article.

2. Data from (1) can be found in this Google Docs spreadsheet

Feb 24 2012

I am Dr Faustus

Ananyo Bhattacharya writes in the Guardian that “Scientists have sold their souls – and basic research – to business“. I wish, respectfully, to dispute this statement.

The article is built around the assertion that basic research in the UK has been corrupted by the idea that it must demonstrate a degree of usefulness, in particular to commercial interests.

Bhattacharya says:

“it is worth noting that the overwhelming majority of game-changing ideas and inventions have not come about as a result of scientists addressing the needs of business.

This is utter cobblers, have you heard of the Industrial Revolution? Do you know that that power is measured in Watts, after the steam engine designer James Watt or that the units of energy, Joules, are named for James Joule a brewer at the forefront of technological improvements for his brewery. What about the transistor, invented at Bell Labs? How about Lavoiser and the foundations of chemistry?  These people may well have appeared to do their research as what we would describe as a “hobby” but they were strongly motivated by the businesses in which they worked at a time when the corporate research laboratory simply didn’t exist nor did the university research department. Even the work that Isaac Newton did was very relevant to commercial interests in his time, the motions of the moon and planets which can be derived from his laws of gravitation were important to navigation, and therefore trade. His work on the telescope can be seen in a similar light. The weaker version of this argument is that single causes for scientific discoveries simply do not exist, they arise from a combination of factors including straightforward curiosity, commercial interests, dependent discoveries, national prestige amongst other things.

Science has also been part of the entertainment business, it still is. Robert Hooke was employed by the Royal Society to provide scientific demonstrations to its members, similarly Michael Faraday was employed at the Royal Institution and long before electricity was used to do anything useful it was a part of the repertoire of travelling lecturers.

In common with many scientists, much of my work in academia was funded at least in part by industry including Courtaulds, Nestle and Unilever for whom I now work. There’s only a subset of scientist who work in areas which attract no direct industrial funding.  Frankly, it is insulting for the rest of us to be told that our work is devalued because of those contacts we have had with industry. Industry is valuable to research because it asks interesting questions, and demands interesting things. How do I make a computer out of plastic? What must a drug that cures Alzheimer’s Disease do? What properties must my avalanche defence barrier have?

It is some form of arrogance to demand money from the public purse whilst simultaneously exclaiming that you can’t possibly describe how you will usefully spend that money; that the fruits of your labour are simply impossible to evaluate. Can you imagine a school or a hospital running this way, let alone a business?

The article also references the “unmeasureability” of basic research impacts, I think there is a degree of truth in this in particular the idea that an impact statement can be written for each and every grant and that the detail of that research proposal can be meaningfully given an “impact value”. However, this approach misses out the critical element of every research project: people.

Most of the people doing research in our university departments will leave them to do other work elsewhere. Trained people are the measurable impact of every research project; their training in basic research skills; their education in specific research skills around their core topic and only finally their knowledge in the very specific area they were taken on to research. As I mentioned earlier several companies spent moderate amounts of money on me through my academic research career what they got from that was not the publication output, I’m confident that my scientific impact in terms of citations will be largely forgotten in a few years time, the important thing was me!

 

Feb 17 2012

Childcare for scientists

Thomas - tired by feeding

Thomas - tired by feeding

Clearly childrearing is primarily a biology experiment but there are elements of physical sciences which are helpful.

 In my past I have done experiments at central facilities like the Rutherford Appleton neutron source, and the x-ray synchrotron sources at Warrington and Grenoble. The deal with these systems is you get a custom-built specialised instrument for a solid block of time and because it is scarce you use it 24 hours per day. Some people, technically called “lucky bastards”, have either highly automated instruments or samples which require long runtimes. I didn’t. So a small team goes off to do the experiment, tending the instrument at 2-3 hour intervals. As the experiments stretch into the small hours skills required for baby care come into play. The group needs to establish an appropriate shift pattern, novices often fall into the trap of refusing to go to bed first. Whilst more senior scientists might take the group to the pub for a couple of pints before buggering off to bed with the words “I’m too old for this”. Experiments like this require a range of tasks to be completed, and in a bleary state this is best done with a system which requires as close to zero thought as possible, make things ready again once you’ve completed a task rather than turning up at the bench to discover you left it in a complete mess. Also record clearly what you are doing so your fellow experimenters can pick it up in your absence (corporal or mental), this includes you. Advanced users have more exciting things to do, such as handling hydrofluoric acid or piranha etch at 2am, there is a clear parallel here with baby poo.

A second area of interest is in temperature-control. Haake water baths are to scientists and temperature control as Marshall amplifiers are to musicians and guitars – other brands are available but they just don’t have the cachet. These devices will maintain water (and samples) at a fixed temperature. It turns out that the description “lukewarm”, used to specify the required temperature for baby feed, has been in use in English since the 14th century, distressingly for a scientist the OED does not provide an actual temperature in SI units corresponding to “lukewarm” (or in any other units for that matter). There is a clear gap in the market here for an espresso-style baby feeding machine which takes as inputs unsterilised gear, expressed breast milk and formula milk and dispenses the required aliquots of “lukewarm” milk – a baby weighing scale could usefully be incorporated into the top of the device. In principle it may be possible to get it to carry out the feeding, although in practice robots struggle with handling soft, squishy, shrieking things.

Finally, one is pretty much forced into preparing a baby feeding spreadsheet. It pains me to be forced to this, I have a “what would chimps do?” attitude to baby-rearing. But these days babies are set feeding targets (150-200 ml per kg per 24 hours), and woebetide any parents failing to meet those targets – they are threatened with a return to hospital by a brigade of midwives whose advice on achieving the target varies greatly but waking the baby up at 3 hourly intervals for a feeding, day and night, is a fixed point. Force-feeding a baby at 3am is quite challenging, changing the nappy first is a good waker-upper for both parties but once feeding the baby gradually slips back to sleep – as illustrated at the top of this post.

The midwife seemed unimpressed by my describing this as being akin to preparing baby foie gras.