At last the memorable night has come. If the weather in Bavaria stays as is now, we might have the chance of repeating the observations of the moon exactly 400 years after Galileo’s. Although Galileo has almost certainly observed the moon before November 30, 1609 (have a look for instance here) and this date might only be a symbolic one, yet it is a good one to celebrate. To avoid the risk of sounding rhetoric, let me quote what Johannes Kepler wrote in his Dioptrice:

Oh telescope omniscient and more precious than a sceptre,

who holds thee in his right hand is a true king, a ruler of worlds;

amongst all astronomers it seems that Galilei has been the first

to whom holding this sceptre fell.

This post is about the terror brought about by astronomy. Just personal considerations and feelings: nothing to be taken very seriously and born from the desire of sharing with others (who might feel the same way but never dared to admit). I recently discovered that, more and more as I am getting of age, I like small rooms. When I am outdoors, I prefer to be in the woods rather than in an open field or over the sea. Also, I tend to concentrate better when it is cloudy. I tried to analyze these feelings more closely, hoping not to find out I was getting paranoid ;-).

But I think I finally found out where these feelings come from. It is the fear of emptiness. When the sky is clear and the night comes, all of a sudden I am exposed to the inconceivable depths of space. And this makes me feel lost, cast away in the most extreme way. It is like being on the edge of a bottomless precipice.

Clouds act like a curtain. They do not remove the vacuum behind them. But at least they hide it, making me feel more “at home”. So do small rooms (like my office here, or my small working room at home). But I am aware this is only an illusion, for I clearly stay on a pinnacle, ready to fall.

And this notwithstanding I grew up with the concept of an immense universe. I cannot image what it must have been when, all of a sudden, somebody started arguing that the universe was much more extended (unimaginably more!) than mankind had ever suspected.

I my professional life empty spaces are every day’s business. And this blade-running path, half way between terror and excitement, is astounding.

I realized that I never wrote about my scientific research (which actually is one of the two sides of my professional life, the other being my functional duties for the European Organization for Astronomical Research). As you may have noticed from my short resumee in the CosmicDiary, I mainly work on Supernovae. Soon there will be a Feature Article on this, so I will not insist too much on this here. Supernovae are the dramatic fate of some stars and are amongst the most energetic phenomena we know. The bottom line is that they eject all (or a large part) of the stellar content into outer space at speeds that reach a significant fraction of the speed of light. In doing this they enrich the surrounding medium with the chemical elements synthesized in their interiors during their “normal” lives and also with the species produced during the explosion itself. Because of the high velocity and mass of the ejected material, they also cause shock waves that sweep the surrounding interstellar medium, causing all sorts of phenomena (escape of material from the galaxy, induced collapse of clouds that would form other stars, and other amenities).

A computer simulated fractal interstellar cloud (credit F. Patat).

My work is mostly in the observation of the events, especially when they occur in close-by Galaxies, typically in the Virgo Cluster. You will see one example in the forthcoming Feature Article. Recently I have been interested in the nature of the progenitors of a special sub-class of Supernovae, called Type Ia. While doing this, I stumbled upon an effect which had not been considered before. The interstellar medium appears to be patchy on all scales (technically one would say that it has a fractal structure). Imagine you have a supernova that explodes behind such a patchy sheet of obscuring material. Then you can guess that the luminosity of the SN as seen by a far observer would appear to vary because the light would have to cross regions of the cloud with different opacity. This is similar to what happens when you look at the sun and clouds move in front of it. The only difference is that in the astronomical case is the “sun” that grows bigger and bigger as time goes by. So what, you might ask…

Well, not very much is known about the small structures in the interstellar material and the study of supernovae might shed some light on this. And this is exactly why in the last few months I have been busy with modeling the scenario I just depicted. For doing this, I had to go through the nice exercise of creating clouds with computer simulations. A very nice experience, half way between astrophysics and computer graphics. You can see an example in the above picture (it just came out of my computer, a few minutes ago). Now, the whole game is to calculate how a supernova explosion would look like as seen through clouds like this. Of course, since the cloud structure has a strong random component, this means running a large number of calculations to get, in the end, a statistical estimate. What is usually called Monte-Carlo simulations. As you probably guessed, the name Monte-Carlo comes from the fact that this method makes use of pseudo-random, computer-generated numbers. Similar to the roulette outcome in a Casino…

Curious about the results? Just wait a bit more

Observing Jupiter and the Galilean Satellites.

This has been an “all-astronomy” week-end. It started when I got back from the office. I had promised my kids we would have watched Jupiter and its satellites early in the evening. And so we did. In the days before we had done some preliminary attempt, using my old, beloved f/10 MTO Maksutov. Jupiter was around the meridian, just above the big, bright glow cast by the town of Munich (there will be a post on light pollution soon…). As a side effect, the kids experienced how disturbing street lights are.

So, when I got back home I found them ready in full astronomical gear, equipped with pencils and notebooks. The idea was to observe Jupiter and draw some sketches in subsequent nights, so to clearly see whether what Galileo had seen (and told us) was indeed right (this is the way I sold the experiment to them). They were very enthusiastic about it, especially the little one (3.5 years), who had his own concept of astronomical

Jupiter and ithe Medicean satellites on 19/11/2009 (Stellarium).

observations. It took me quite a while to convince him that our target was high in the sky and not the window across the street (he said he was looking for Long John Silver, because Billy Bones had told him to beware of the man with one leg…). The girls (6 and 9) were more professional about it and took the whole business very seriously, sitting at the telescope, watching, drawing, re-observing and correcting the sketches. The seeing was not extremely good, and the colored stripes were visible from time to time across the disk of Jupiter. I left them alone for a while, so that they could observe at will. Once they asked me to point Vega, to see how it would look like. Nice comparison, indeed. They immediately saw the difference and I think this will stay with them for quite a while.

A sketch of Jupiter and its Galilean Satellites (20/11/2009, 19:05 CEST). Drawing by Costanza Patat. Note the orientation is reversed with respect to the Stellarium map.

When I came back (meanwhile the boy was running around in the garden), they had finished their homework. Impressively enough, the eldest had also put the Great Spot in her drawing. I admit I could not see it in the eyepiece, but she claimed she did. Later on, comparing her drawing with Stellarium, I noticed that, at least, the spot was visible and more or less in the same position as she had portrayed. However, two nights after she painted the Red Spot in the same position, while at the time of those observations the spot was not supposed to be visible…

Our astronomical session was interrupted by Mom calling for dinner. But we left the improvised observatory with the promise of re-observing Jupiter in the next nights, to see whether it would look any different.

My astronomical commitments for that evening were not over, though. At nine I had a videoconference planned. So, back in the office after dinner and ready to talk to an Italian group of amateurs of the Friulian Association for Astronomy and Metereology. I had sent them the keynote presentation in the afternoon and the idea was to have a Skype session. They would run the presentation and I would comment it live. Although not exactly the same as being in front of the public (something I enjoy very much), the thing worked rather fine. The talk was about my last trip to Paranal, the commissioning of X-Shooter and the life of an experimental astronomer in general. At 22:30 the conference was over and I got back home. All little astronomers were deeply sleeping. Observing the smallest I could not tell whether he was dreaming about Jupiter or Jim Hawkins (his favorite in these days).

Jupiter on 21/11/2009 (17:31 CEST). Drawing by Costanza Patat.

On the next evening, the kids were ready around 17. The configuration of the satellites was a very interesting one. All four were on one side of the planet. But most important, Io would disappear behind the big planet in about 45 minutes. This would offer the kids the chance of seeing the system evolving just under their eyes (and well before dinner’s time). Before starting with Jupiter we pointed the young, crescent Moon. It was wonderful and the kids were delighted to look at the craters. In particular, the peak of a mountain on one edge of the terminator was shining in the middle of a dark area. It was not the first time they saw the Moon with a telescope (during summer vacations we always have some observing session with friends). Nevertheless, they looked thrilled. When they were satisfied with the Moon it was the turn of Jupiter. They were looking forward to see it and to compare the image in the eyepiece with the drawings they had obtained during the previous observations). And, yes! They could immediately see that something had changed and that, in particular, one of the satellites (Io, as it turns out), was very close to the disk of Jupiter. Their wonder grew during the next hour, as the satellite was getting closer and closer, to disappear behind the planet around 18:50 CEST. I must confess I was excited too. It is only with a direct experience that you can fully understand what it must have been for Galileo during those memorable nights in Padua, back in January 1610.

The plan for the evening moved towards a more [G]astronomical context. The day before I had announced an home-made Mexican dinner to close the observations. And so was it. Fajitas, nachos, hot deeps and so on. A glorious evening!

I occupy my free time doing very different things. One of them is archaeoastronomy. There will be a post on this topic, which I found quite intriguing (meanwhile you can find some more info here). One of the most common (and easiest) studies in archeoastronomy (although in this case the term archaeo is probably not really appropriate) is about the orientation of old churches. While reading the available literature on this subject, I found a recent, very well written and informative book, The Sun in the Church - Cathedrals as Solar Observatories, by J.L. Heilbron. At some point, in the chapter The Accommodation of Copernicus, under the section Book Banning, subsection Galilaeus Sanctificatus (!), I found a very interesting piece of information (pp.210-211). Here follow the relevant excerpts.

Pio Paschini (1878-1962).

“The removal of Galileo’s Dialogo from the Index canceled a black mark against the book but not against its author. The official rehabilitation of Galileo took another century and a half. It began around 1940 in connection with the three hundredth anniversary of Galileo’s death. That was not a good time for a party. Nevertheless Pope Pius XII approved a campaign to demonstrate the Church’s openness to science. As an indication of this openness and on the recommendation of the Pontifical Academy of Sciences, he commissioned an unrestricted biography of Galileo. The assignment went to Monsignore Pio Paschini, rector of the Pontifical Lateran University, a historian known for his balanced account of the Church during the Reformation.”

My surprise was two-fold. First of all I was not aware that the Pope had commissioned such a work (this already tells you the level of diffusion this book had. But wait…). Secondly, Pio Paschini (1878-1962) was born in Tolmezzo, some 25 km from my village in Friuli (Italy). He had actually written a very extensive History of Friuli, which I knew rather well.

That I had to learn about this in a book written by a Berkely professor was astonishing in itself. But my wonder was going to grow even larger in the next lines.

“It was a bold choice, since Paschini tended to be liberal and judicious. These virtues worried some of the Pope’s senior advisors, who had the satisfaction of being proved right. Paschini took Galileo’s part, admitted that the condemnation had been an error, and lost no opportunity for criticizing the Jesuits, on whom he blamed the entire affair. The Jesuits objected. Paschini’s two-volume work disappeared in the review mechanism, much as academic articles submitted to scholarly journals do today. The anniversary date, 1942, was long past when the Vatican journal, Civilta’ Cattolica, got around to the subject. It admitted that the Church, or rather, intemperate and ill-informed churchmen, had erred in condemning Galileo; and it recommended that the best use that could be made of this fact was to forget it. Paschini understood and fell silent. As a reward he was made a bishop two months before he died and an honorary member of the Pontifical Academy of Sciences, which had opposed the publication of his work.” With this unimaginative solution, the Church shut up a work that it had commissioned to demonstrate its openness.”

The book had to wait. The third centenary of Galileo’s birth (1564) was just missed and the book appeared after its author’s death.

Vita e Opere di Galileo Galilei (Rome, 1965).

“Paschini’s biography of Galileo appeared in 1968, heralded as an indication of the Pope’s program for the peaceful coexistence of religion and science. The general scholarly press reviewed the book favorably. Lay and clerical critics commended its balance. Very few knew that, to use an old expression of the censorship, the book had in effect been indexed ‘donec corrigatur’, and then corrected before publication, by the keeper of the Jesuit’s archives. Since the publication of this collaborative work, efforts at rapprochement between science and religion have intensified, particularly under the auspices of John Paul II. In 1979, on the occasion of the centenary of Einstein’s birth, the Pope told is Pontifical Academy of Sciences that he wanted theologians, scientists, and historians to work together on a reassessment of the Galileo affair. He endorsed Galileo’s principles of biblical exegesis. He gave as an earnest of the project Church’s sponsorship of Paschini’s biography, without knowing (let us hope) that it had been censored more crudely than the old books on heliocentric astronomy.”

The 0.7m Pio Paschini Telescope, Zuglio-Italy (credit: Gruppo Astronomico La Polse di Cougnes).

The edition I managed to get dates 1965, so I am not sure where Heilbron got his 1968. But it does not make very much difference. The book had been concealed for more than 20 years and his author never received the appraisal he deserved. Also, for some reason, it did not get very much diffusion outside of scholar circles. You can find some mention to it here.

At the time I was reading The Sun in the Church, a new 0.7m telescope was about to see his first light on the Friulian alps, a few km north of Tolmezzo, were Pio Paschini was born. I was acting as a scientific consultant for the amateur association that manages the site, called La Polse di Cougnes. I thought that in consideration of all his objective work on Galileo (although certainly supported by his submissive Friulian spirit, for Paschini the whole business must have been a hard knot to swallow), and in sight of the IYA2009, dedicating the telescope to his memory in his own land was the least we could to. I proposed this to the coordinator of the association, who accepted this immediately. And so, on September 27th, 2008, the telescope was solemnly dedicated to him. Since then hundreds of visitors enjoy the sight of the celestial wonders.

Hopefully, in the future his work will be properly recognized and the Church will take all necessary steps to give proper credit to his commitment for an objective evaluation of the Galileo affair.

The 30th of November is approaching, and this brings back to me memories of the time when I first read some excerpts of The Dialogue on the Great World Systems and the Starry Messenger. This must have happened during my last year at the High School (1984). In the occasion of the IYA2009 I re-read them. While doing this I stumbled upon two interesting books: The Crime of Galileo (Chicago: The University of Chicago Press, 1955) by Giorgio de Santillana (professor at MIT) and Vita e Opere di Galileo Galilei (Rome: Herder, 1965), by Pio Paschini (professor at the Pontifical Lateran University in Rome). In the next post I’ll tell you how the second is related to a very interesting story. To wet your appetite I’ll just tell you that the book was commissioned by the Pontifical Academy of Sciences for the 300th anniversary of Galileo’s death in 1942. The book was ready by 1943, but it was rejected by the Church and remained concealed until 1965, when it was published. As a matter of fact, Giorgio de Santillana was not aware of it when he published the Crime of Galileo, which is the subject of this post.

Giorgio de Santillana

Most of you probably know de Santillana because of his famous Hamlet’s Mill, written together with Hertha von Dechend. It is a dense, multidisciplinary book about the astronomical roots of myth. An interesting reading, indeed.

But he has worked a lot on Galileo. His edition of the Dialogue won rich praise from the critics. It was right during this hard work that the seed of The Crime of Galileo was planted. Here follows an excerpt from the Preface:

“This work is not the result of a plan afterthought. As I tried to clear up the astonishingly complex background of Galileo’s Dialogue on the Great World System, I was drawn to the drama which played a decisive part in that fateful event of modern history, the secularization of thought. It seemed strange to me that, after so much research and controversy, the story events as I found it should make so little sense. As I worked, it became clear that a large area of the puzzle had remained oddly disassembled to the present day, by what looks like an inexplicable tacit agreement between the warring factions.”

And further down:

“Galileo did not come to grief as “the scientist” facing a religious credo. [...] Both his friends and and his enemies saw in him a unique type of creative personality, whose essential achievement might very well be conceived to stand or fall with him. He was a classic type of humanist, trying to bring his culture to the awareness of the new scientific ideas, and among the forces that he found aligned against him religious fundamentalism was by no means the strongest.

It is difficult to see the actual shape of the conflict in these matters so long as we remain under the spell of a misunderstanding tacitly accepted by both sides: the idea of the scientist as a bold “free-thinker” and “progressive” facing the static resistance of conservatism.”

Here de Santillana’s unconventional vision of the Galileo case starts to emerge in its far reaching aspects:

The Crime Of Galileo -The University of Chicago Press - 9th Impression - 1970.

“The confusion goes on unremittingly even today, for the Galileo affair is far from dead, and every decade brings a new “line” and new suggestions meant to explain it away, just as it brings a repetition of the ancient rationalist war whoops. The side that stands for the authorities neither is, nor by any means has been, all Catholic. [...] Most of the literature through which one has to wade deserves no mention at all. It ranges from average casual incompetence to prevarication and plain filth. Let it go back to whence it came from.”

During the painstaking research work for his edition of the Dialogue, de Santillana realizes that things did not go exactly the way we have always been told.

“The long-drawn-out polemic is not strictly, I hope to have made it clear, one between the confessional and the anticonfessional faction. It has been made to look like that; in reality it is a confused free-for-all in which prejudice, inveterate rancor, and all sorts of special and corporate interests have been the prime movers. Those who dragged and keep dragging the Church into it are no candid souls. As L’Epinois says rightly, the Church has all to gain and nothing to lose from the truth.”

And it becomes more explicit here:

“It has been known for a long time that a major part of the Church intellectuals were on the side of Galileo, while the clearest opposition to him came from secular ideas. It can be proved further (or at least I hope I have done so) that the tragedy was the result of a plot of which the hierarchies themselves turned out to be the victims no less than Galileo - an intrigue engineered by a group of obscure and disparate characters in strange collusion who planted false documents in the file, who later misinformed the Pope and the presented to him a misleading account of the trial for decision.”

If you read this carefully, you will understand the implication is a very serious one, one I had never been made aware before. Far from claiming the Church was innocent, de Santillana points the finger towards unsuspected/unsuspectable people: academics, the very colleagues of Galileo. And this rises the important question about how the scientific novelty is received by the academic establishment. At the time of Galileo as well as of today. A matter to be deeply meditated by us scientists.

“An objective account ought to be more relevant to a decent understanding than all the innuendoes, diversions, and stage sets invented around it on both sides. By pinpointing the culpability of a few individuals, it tends to absolve a far greater number who had stood hitherto under the darkest suspicion [...]. Once recognized, the facts should lead us forward to the problems of present reality and disperse this perennial battle wit windmills”.

An eye-opener, illuminating book, built on documents and not on philosophical speculations. Definitely a must read for someone who wishes to reach an informed opinion on the Galileo affair.

Very interesting and intriguing is also the case of Vita e Opere di Galileo Galilei. But for this you will have to wait for the next post…

The nearby galaxy NGC300 (Digital Sky Survey). The position of the optical transient is marked by a cross.

Last year, while spending a nicely warm morning in Northern Italy, I got a phone call from Avik Harutyunyan, a post-doc working in La Palma at the Italian National Telescope “Galileo”. He was quite excited. The discovery of a bright optical transient in the nearby galaxy NGC300 had just been announced in one of the electronic telegrams issued by CBAT. The word “optical transient” is normally used to indicate a new source, whose nature is yet unknown. In these last years the interest for these transients has been steadily growing, because it looks like there is a class of objects that could fill the so called “gap” between the tremendously powerful Supernova explosions and the more discrete fireworks of Novae. Much more on these new beasts will be found by Panstarrs, Sky Mapper and the Palomar Transient Factory.

Andrea Pastorello and his colleagues in Belfast are working hard on this topic and, when I can, I collaborate with them. Actually, this is why Avik called me. In the last years I have been getting deeper and deeper into polarimetry, a technique that can give you information about the geometry of the object you are observing. For doing that, you “just” need a big telescope, because the technique is “photon starving”, which means that at a “small” telescope (say of a few meters), it would take ages to get enough signal on your detector.

The region of the optical transient in NGC 300 (ESO VLT-FORS1 archival image).

Once more I said to myself that I had chosen the wrong astrophysical field… I have been working on supernovae for more than 15 years now, but I hate them! They always blow up during week-ends and vacation time %(*&$!$@#! (Note that Shri Kulkarni, one of the bosses of transients, uses to say that supernovae are for the lazy people. I hate Shri too…). The bottom line is that in the next few days we put together a proposal for ESO’s Director General Discretionary Time, to get some time at the Very Large Telescope. The idea was to obtain spectropolarimetry on two different epochs (plus a high resolution spectrum to get detailed information on the velocity structure of the ejected material). As you can imagine, the optical transient in NGC300 became the target of a number of campaigns around the world (a number of papers have already appeared on this object). But the polarimetric capabilities of the VLT are quite unique and this, coupled to its large diameter (8.2m), put us in a privileged position. The proposal went through and the observations were successfully carried out at the beginning of July.

The optical transient in NGC300 (try to find it yourself). The image was taken with VLT-FORS1 as part of our observations.

That was the “easy” part. I spent the following months analyzing the data and trying to make sense of them. At some point I felt I had reached a dead end and I decided to abandon the project for a while (sometimes thinking about other topics helps to find the solution, or at least a different way of looking into the problem). I could do this because I was almost sure no competing team had this kind of data. This is often not the case, and it helped a lot. Last spring I went back to the data, I discussed a lot with other people working in the field and, in the end, I came up with a solution. What the data were telling us is that there were two components that contributed to the signal: an interstellar one, having nothing to do with the outbursting source, and a circumstellar one, possibly related to the progenitor star. And this one was strongly asymmetric, suggesting that the star had undergone one or more episodes of asymmetric mass loss. Polarimetry had done its job and there was enough meat to write a paper. Which I did in the next few months, managing to submit it to Astronomy and Astrophysics just before going on summer vacations.

ESO-FORS1 mounted at one of the VLT units.

The big discussion about these transients (there was another one, very similar to OT-NGC300, in 2008) is whether they are real explosions or just the superficial outburst of some exotic, very luminous, variable star. This was one of the many topics discussed at the Stellar Death Conference in Santa Barbara - CA. In one of my next posts I will talk about it, probably the best SN conference I have ever attended. Although it was “disturbed” by the discovery of the SN of the year, dubbed SN2009ig. While all young post-docs and students were spending the evenings in a nice jacuzzi, I was triggering new observations and reducing data with my laptop in my room.

I hate Supernovae!! Sooner or later I will switch to the most quiet objects in the universe. Oh, those good old times of Aristotle, when the Universe was unchanging.

When I got back from holidays I had a nice surprise. The paper had been accepted for publication in A&A. If you wish to see how it looks like, just click here.

You may wonder why I post this today. Well, I am going through the manuscript proofs readings, which is the most boring part of the whole process and I though I needed some short distraction.

Although not among the core activities of a professional astronomer, popularizing science to the public is a fundamental task. Since a researcher is not necessarily a good communicator (you can be an excellent piano player, but you might be absolutely dull in teaching it to a kid), I believe this job is better done by a professional, who devotes all her/his efforts trying to find the right compromise between scientific rigor and making the topic appealing to the targeted public.

Actress Sandra Cosatto and percussionist Ermes Ghirardini preparing for BioXtremity (Sep 2009).

However, an active scientist can convey to the public her/his first hand experience which, properly shaped, I reckon can have a strong impact on the listener. She/he also acts as an (often unconscious) living example of the real possibility of becoming a scientist. So, when my professional commitments allow it, I always accept requests for public seminars in schools, theaters and small amateur clubs. Among others, last summer I gave one in my town in Italy. For the first time I did two new things: a Skype video-link to Paranal (my colleague Paul Lynam was on the other side of the ocean, in Chile) and a live spectroscopic demonstration. Being an experimental astronomer (whatever experimental here means…), I strongly believe in the power of the experiment in conveying concepts and firmly imprint them in the listener’s memory. From the feedback I got afterwards (the talk was attended by some 250 people, ranging from kids to grannies), those were the two things that mostly impressed and reached the mark. Another ingredient I make us of is interspersing the scientific talk with personal anecdotes and, more recently, adding live music performances by professionals (for instance to accompany sequences of astronomical images at the beginning/end of the presentation). I use them as “relaxing” points and they prove to be very effective, especially with kids (see Ermes Ghirardini rehearsing for “Astronomy and Emotions”, Artegna September 2009).

Technician (and old friend) Armando Fornasiere setting the Theater stage in Artegna (Italy).

The presentation was attended by a teacher who, inspired by what she had seen, afterwards came to me proposing a lecture to be held in front of some 320 kids, 13 years old, at their last year of the Intermediate School. This would perfectly fit - she said - with the activities they had undertaken during the International Year of Astronomy (Galileo, the telescope, the Copernican Revolution, and so on). But, most important of all, she was asking me to convey the enthusiasm for science and research. Mmm, not an easy task with 13 year old youngsters… My fears were two-fold: i) Even admitting I would manage to capture their attention for a while, I would never be able to keep their attention for 2 hours (this is what she was proposing for the duration); ii) I would never accomplish to surprise them. With all those 3-D games and computer programs they have already seen much more than I can even imagine… However, I like challenges and I finally accepted the offer. I must say that having those concerns in mind I took the thing rather seriously and so I started

Disassembling an old binocular to get a cheap collimator lens.

preparing the presentation and all required paraphernalia almost immediately. My first goal was be to build a better version of my SFTM spectrograph. Oh, yes, SFTM stays for Spectrograph For The Masses. Clearly, one could deliver the basics of spectroscopy using pictures taken from the Internet, without the need of screwing a single bolt. But that was exactly what I wanted to avoid. Therefore, after putting all kids to sleep (I have quite a number of them, mind you), for a number of nights I spent many hours in my improvised optical lab in the basement (much to my wife’s badly conceived disappointment). The idea was to build a simple spectrograph that would easily allow me to show in real time the spectra of different sources, to illustrate why spectroscopy is so important and why it transformed astronomy into astrophysics.

I knew I had an old Russian binocular somewhere. After finding it I quickly managed to take it apart (a

A diffraction grating mounted on a photographic slide frame.

specialty I acquired when I was a kid, much to my parent’s dismay: “The only good toy is the dismounted one“. It looks like my last kid inherited this attitude, extending the concept also to things which are not necessarily toys…), to extract one of the objective lenses to be used as collimator. The next step was to get the dispersive element. In the projects you find in the Internet a piece of an old CD/DVD is used for that purpose. But I preferred to adopt a grating foil, because it has a higher dispersion and it works in transmission. You can get it online in several optical stores for a few EUR/USD. After cutting it to the proper size, mounting it in a slide frame, and screwing it on an L-shaped holder (a few cents in any hardware shop), the dispersive element is ready for use. As for the spectrograph entrance, I adopted the common two-blades solution, gluing them on a piece of cardboard. The backbone of the spectrograph is a simple

The SFTM instrument assembled. The tow-blades slit is visible at the top, while the contraption at the bottom is the webcam and its holder

piece of wood, on top of which I fixed the various components. I then placed it in an old shoe box, internally covered with black paper to avoid spurious light. But the real “+feature” of the spectrograph is its coupling to a webcam, which makes SFTM suitable for live performances. In fact, during the presentation, you can start your favorite webcam software and broadcast the real time images on the large screen. After building a simple holder for the collimator and the webcam (making use of quite a number of pieces of metal, leftovers of never ending IKEA-mounting sessions), and after going through some integration and alignment procedure, the instrument was ready for commissioning.

Although there is lots of room for improvement, the results where not bad. By the way, the whole thing gave me the chance to refresh Spectroscopy-For-Dummies. As usual in the teaching process, things become much more clear when you have a well defined target in mind. While learning, many times you tend to lie to yourself. This is dangerous when you will have to stand in front of a potentially aggressive audience, which is just looking forward to get you wrong somewhere… The machine was finally ready to go on stage. For the sources I decided to keep things simple: an incandescent light (to mimic a black body) and a compact fluorescent lamp (to simulate an emission nebula).

Spectroscopy is the key tool in astrophysics. It basically gives you two kinds of information: chemical composition/physical conditions and information about the kinematics

Spectrum of a compact fluorescent lamp taken with SFTM.

of the emitting material. While the first can be clearly illustrated by the two lamps, the second is not feasible with a simple laboratory experiment (you would need to move the source at very high speeds, a bit too high to achieve them in a theater ;-). So, I had to change type of waves and, of course, the next choice is acoustic waves. What I wanted to convey is why spectroscopy tells us about the radial velocity of the emitting body.

After removing a loudspeaker from an old radio, I soldered a couple of wires to connect it to a CD player. On a CD I then recorded a 440Hz sinusoidal sound (you can do this, for instance, using Audacity). After securing the loudspeaker with an extra wire (you do not want the loudspeaker to accidentally hit somebody sitting in the first row), the Ledan-Doppler-Demonstrator was ready for use. The idea is very simple. After switching on the CD player, you let the audience hear the sound,

The VLTruvian man (a self-portrait on a full moon night in Paranal).

so that they can memorize the zero-velocity frequency. Then, firmly holding the loudspeaker by the wire, you start turning it, like a lasso. This simulates, for instance, a star in a binary system as seen by a distant observer. The audience will perceive a time-varying frequency (in the 60’s there was an audio effect called Leslie, that was based on the same concept), higher when the loudspeaker moves towards the public, lower when it goes away from them. I tested at home with my kids and it seemed to work just fine (if the “orbit” has a radius of one meter and the rotation period is one second, then the frequency variation is about 8 Hz, well perceivable by the human ear).

So much for the experiments. I then took a good time to prepare the talk, with images and music. I decided to start off using a picture of myself when I had their age (and astronomy was just appearing on my horizon). I would tell them that I was fascinated by the heavens, but also that I wanted to look through a telescope, to see those wonders with my own eyes. And then explain them that early love for the skies soon became a real passion and carried with itself a dream: become an astronomer and make my own research with the biggest telescopes. I would close this introduction showing a picture of myself, taken on Paranal. A dream that finally turned into reality.

The date for the lecture was set for the 3rd of November. Of course, not by chance in November, the Galilean Month. And, in fact, my presentation included an homage to Galileo and his discoveries.

Right after the start I was shown to be wrong on both assumptions: i) the kids were extremely silent and focused; ii) I could feel the wonder growing in their eyes (well, yes, there were a few exceptions…). SFTM worked perfectly. And so did the Ledan-Doppler-Demonstrator, but not the way I had originally imagined. In a surge of enthusiasm, given the large volume of the theater, I decided to boost a bit the loudness of the 440Hz sound. The few watts loudspeaker reacted quite abruptly, emitting a dieing hiss and a cloud of smoke. The audience went completely silent. It does not happen very often I properly react to unforeseen accidents. But this was the case. “As you have just seen, science’s road can be paved with failures. And it is also on those failures that our knowledge of the world is based”. They were so impressed by the “show” and the short philosophical argument that followed, that I have decided to make the loudspeaker blow up on purpose next time, possibly with a flame (I will have to consult with my good old friend/inventor Armando Fornasiere. He’ll certainly find a solution). But I will also make sure I have a robust loudspeaker for the real Doppler-Demonstrator

The bottom line is that, though really time consuming (and this in many cases is a show stopper for the active researcher), it is worthwhile. The applause I received in the end (more similar to the one of a concert that of a scientific talk I must say) was indeed rewarding. And what makes me proud is that they did not applaud me. They did applaud science, its wonders, its women and men.

I am working on somthing more substantial for this blog. The outcome of this activity should appear soon. Meanwhile, asked by Helen Gavaghan, editor of Science, People and Politics, I have written a review of “The Age of Wonder” by Richard Holmes. You can find it online here. Although quite unusual for an astronomer, I found this experience estremely interesting, challenging and gratifying at the same time.

Frederick William Herschel (1738-1822).

The book, which has been awarded several prizes and rapidly became a best-seller, is about the scientific developments which took place in England in the 18th century. A number of scientists played a role, but for me (and my astronomically biased vision the most important/impressive was William Herschel (and his sister Caroline, as one gets to discover reading the book).

Just read the book. If you think you have a radical passion for astronomy (as I thought I had), then compare it with Herschel’s and think about it. Besides building over 200 telescopes and spending every single clear night observing, he had some amazing intuitions. Among other things (and I admit I was not aware of it), he has discovered the existence of infrared radiation (which he demonstrated placing some thermometers after a prism!). Curiously, following Herschel’s footprints, J.W. Ritter, a controversial scientist that worked here in Munich, has discovered the ultraviolet radiation.

But what is perhaps most striking in this book, is the tight relation between science and arts during The Age of Wonder. The discussion about Vitalism, the very existence of God, the sudden explosion of the universe’s diemensions (from astronomy) and age (from geology) light up a debate where art plays a fundamental role, in both ways, being influenced by and influencing science.

Indeed, a great piece of work.