Perseid Meteor Shower 2018

Perseid meteor, 2015-08-13

Tonight (August 12–13, 2018 UTC) the Perseid meteor shower will peak.  This meteor shower occurs every year around August 12th as the Earth passes through the orbit of debris from comet Swift-Tuttle.  This is one of the most reliable and intense meteor showers and, in ideal conditions (clear, dark sky and dark-adapted eyes) you may see a meteor a minute.  (As with everything, Pareto is on the job—there are many more dim meteors than bright ones.)

This year, the Moon will not interfere with observation, so there should be a good show.  Here is information about observing the Perseids.

It couldn’t be easier.  Any time after around 23:00 local time (the later the better, as the “radiant”—the point in the sky from which the meteors appear to come—rises higher in the sky) go out to a place as far as you can find away from street lights or other interference and look up toward the northeast.  Allow time for your eyes to dark-adapt.  Once you can see the Milky Way, you should be able to see the dimmer meteors.

Sometimes you’ll be lucky and see a bright fireball which leaves a persistent trail that lasts for several seconds.  Don’t expect this, however: the last one I saw was in 2015, as pictured above.

I’ll not be watching for Perseids tonight.  After a perfectly clear day, around the end of astronomical twilight clouds rolled in and completely obscured the sky.  The peak of the Perseids is broad, however, so if it’s clear I’ll try to-morrow.

If you have clear skies tonight, go out and have a look.  You need no equipment other than the Mark I eyeball and, if in skeeter country, a splash of DEET.

Clear skies!

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Saturday Night Science: Losing the Nobel Prize

“Losing the Nobel Prize” by Brian KeatingEver since the time of Galileo, the history of astronomy has been punctuated by a series of “great debates”—disputes between competing theories of the organisation of the universe which observation and experiment using available technology are not yet able to resolve one way or another. In Galileo’s time, the great debate was between the Ptolemaic model, which placed the Earth at the centre of the solar system (and universe) and the competing Copernican model which had the planets all revolving around the Sun. Both models worked about as well in predicting astronomical phenomena such as eclipses and the motion of planets, and no observation made so far had been able to distinguish them.

Then, in 1610, Galileo turned his primitive telescope to the sky and observed the bright planets Venus and Jupiter. He found Venus to exhibit phases, just like the Moon, which changed over time. This would not happen in the Ptolemaic system, but is precisely what would be expected in the Copernican model—where Venus circled the Sun in an orbit inside that of Earth. Turning to Jupiter, he found it to be surrounded by four bright satellites (now called the Galilean moons) which orbited the giant planet. This further falsified Ptolemy’s model, in which the Earth was the sole source of attraction around which all celestial bodies revolved. Since anybody could build their own telescope and confirm these observations, this effectively resolved the first great debate in favour of the Copernican heliocentric model, although some hold-outs in positions of authority resisted its dethroning of the Earth as the centre of the universe.

This dethroning came to be called the “Copernican principle”, that Earth occupies no special place in the universe: it is one of a number of planets orbiting an ordinary star in a universe filled with a multitude of other stars. Indeed, when Galileo observed the star cluster we call the Pleiades, he saw myriad stars too dim to be visible to the unaided eye. Further, the bright stars were surrounded by a diffuse bluish glow. Applying the Copernican principle again, he argued that the glow was due to innumerably more stars too remote and dim for his telescope to resolve, and then generalised that the glow of the Milky Way was also composed of uncountably many stars. Not only had the Earth been demoted from the centre of the solar system, so had the Sun been dethroned to being just one of a host of stars possibly stretching to infinity.

But Galileo’s inference from observing the Pleiades was wrong. The glow that surrounds the bright stars is due to interstellar dust and gas which reflect light from the stars toward Earth. No matter how large or powerful the telescope you point toward such a reflection nebula, all you’ll ever see is a smooth glow. Driven by the desire to confirm his Copernican convictions, Galileo had been fooled by dust. He would not be the last.

William Herschel was an eminent musician and composer, but his passion was astronomy. He pioneered the large reflecting telescope, building more than sixty telescopes. In 1789, funded by a grant from King George III, Herschel completed a reflector with a mirror 1.26 metres in diameter, which remained the largest aperture telescope in existence for the next fifty years. In Herschel’s day, the great debate was about the Sun’s position among the surrounding stars. At the time, there was no way to determine the distance or absolute brightness of stars, but Herschel decided that he could compile a map of the galaxy (then considered to be the entire universe) by surveying the number of stars in different directions. Only if the Sun was at the centre of the galaxy would the counts be equal in all directions.

Aided by his sister Caroline, a talented astronomer herself, he eventually compiled a map which indicated the galaxy was in the shape of a disc, with the Sun at the centre. This seemed to refute the Copernican view that there was nothing special about the Sun’s position. Such was Herschel’s reputation that this finding, however puzzling, remained unchallenged until 1847 when Wilhelm Struve discovered that Herschel’s results had been rendered invalid by his failing to take into account the absorption and scattering of starlight by interstellar dust. Just as you can only see the same distance in all directions while within a patch of fog, regardless of the shape of the patch, Herschel’s survey could only see so far before extinction of light by dust cut off his view of stars. Later it was discovered that the Sun is far from the centre of the galaxy. Herschel had been fooled by dust.

In the 1920s, another great debate consumed astronomy. Was the Milky Way the entire universe, or were the “spiral nebulæ” other “island universes”, galaxies in their own right, peers of the Milky Way? With no way to measure distance or telescopes able to resolve them into stars, many astronomers believed spiral neublæ were nearby objects, perhaps other solar systems in the process of formation. The discovery of a Cepheid variable star in the nearby Andromeda “nebula” by Edwin Hubble in 1923 allowed settling this debate. Andromeda was much farther away than the most distant stars found in the Milky Way. It must, then be a separate galaxy. Once again, demotion: the Milky Way was not the entire universe, but just one galaxy among a multitude.

But how far away were the galaxies? Hubble continued his search and measurements and found that the more distant the galaxy, the more rapidly it was receding from us. This meant the universe was expanding. Hubble was then able to calculate the age of the universe—the time when all of the galaxies must have been squeezed together into a single point. From his observations, he computed this age at two billion years. This was a major embarrassment: astrophysicists and geologists were confident in dating the Sun and Earth at around five billion years. It didn’t make any sense for them to be more than twice as old as the universe of which they were a part. Some years later, it was discovered that Hubble’s distance estimates were far understated because he failed to account for extinction of light from the stars he measured due to dust. The universe is now known to be seven times the age Hubble estimated. Hubble had been fooled by dust.

By the 1950s, the expanding universe was generally accepted and the great debate was whether it had come into being in some cataclysmic event in the past (the “Big Bang”) or was eternal, with new matter spontaneously appearing to form new galaxies and stars as the existing ones receded from one another (the “Steady State” theory). Once again, there were no observational data to falsify either theory. The Steady State theory was attractive to many astronomers because it was the more “Copernican”—the universe would appear overall the same at any time in an infinite past and future, so our position in time is not privileged in any way, while in the Big Bang the distant past and future are very different than the conditions we observe today. (The rate of matter creation required by the Steady State theory was so low that no plausible laboratory experiment could detect it.)

The discovery of the cosmic background radiation in 1965 definitively settled the debate in favour of the Big Bang. It was precisely what was expected if the early universe were much denser and hotter than conditions today, as predicted by the Big Bang. The Steady State theory made no such prediction and was, despite rear-guard actions by some of its defenders (invoking dust to explain the detected radiation!), was considered falsified by most researchers.

But the Big Bang was not without its own problems. In particular, in order to end up with anything like the universe we observe today, the initial conditions at the time of the Big Bang seemed to have been fantastically fine-tuned (for example, an infinitesimal change in the balance between the density and rate of expansion in the early universe would have caused the universe to quickly collapse into a black hole or disperse into the void without forming stars and galaxies). There was no physical reason to explain these fine-tuned values; you had to assume that’s just the way things happened to be, or that a Creator had set the dial with a precision of dozens of decimal places.

In 1979, the theory of inflation was proposed. Inflation held that in an instant after the Big Bang the size of the universe blew up exponentially so that all the observable universe today was, before inflation, the size of an elementary particle today. Thus, it’s no surprise that the universe we now observe appears so uniform. Inflation so neatly resolved the tensions between the Big Bang theory and observation that it (and refinements over the years) became widely accepted. But could inflation be observed? That is the ultimate test of a scientific theory.

There have been numerous cases in science where many years elapsed between a theory being proposed and definitive experimental evidence for it being found. After Galileo’s observations, the Copernican theory that the Earth orbits the Sun became widely accepted, but there was no direct evidence for the Earth’s motion with respect to the distant stars until the discovery of the aberration of light in 1727. Einstein’s theory of general relativity predicted gravitational radiation in 1915, but the phenomenon was not directly detected by experiment until a century later. Would inflation have to wait as long or longer?

Things didn’t look promising. Almost everything we know about the universe comes from observations of electromagnetic radiation: light, radio waves, X-rays, etc., with a little bit more from particles (cosmic rays and neutrinos). But the cosmic background radiation forms an impenetrable curtain behind which we cannot observe anything via the electromagnetic spectrum, and it dates from around 380,000 years after the Big Bang. The era of inflation was believed to have ended 10−32 seconds after the Bang; considerably earlier. The only “messenger” which could possibly have reached us from that era is gravitational radiation. We’ve just recently become able to detect gravitational radiation from the most violent events in the universe, but no conceivable experiment would be able to detect this signal from the baby universe.

So is it hopeless? Well, not necessarily…. The cosmic background radiation is a snapshot of the universe as it existed 380,000 years after the Big Bang, and only a few years after it was first detected, it was realised that gravitational waves from the very early universe might have left subtle imprints upon the radiation we observe today. In particular, gravitational radiation creates a form of polarisation called B-modes which most other sources cannot create.

If it were possible to detect B-mode polarisation in the cosmic background radiation, it would be a direct detection of inflation. While the experiment would be demanding and eventually result in literally going to the end of the Earth, it would be strong evidence for the process which shaped the universe we inhabit and, in all likelihood, a ticket to Stockholm for those who made the discovery.

This was the quest on which the author embarked in the year 2000, resulting in the deployment of an instrument called BICEP1 (Background Imaging of Cosmic Extragalactic Polarization) in the Dark Sector Laboratory at the South Pole. Here is my picture of that laboratory in January 2013. The BICEP telescope is located in the foreground inside a conical shield which protects it against thermal radiation from the surrounding ice. In the background is the South Pole Telescope, a millimetre wave antenna which was not involved in this research.

BICEP2 and South Pole Telescope, 2013-01-09

BICEP1 was a prototype, intended to test the technologies to be used in the experiment. These included cooling the entire telescope (which was a modest aperture [26 cm] refractor, not unlike Galileo’s, but operating at millimetre wavelengths instead of visible light) to the temperature of interstellar space, with its detector cooled to just ¼ degree above absolute zero. In 2010 its successor, BICEP2, began observation at the South Pole, and continued its run into 2012. When I took the photo above, BICEP2 had recently concluded its observations.

On March 17th, 2014, the BICEP2 collaboration announced, at a press conference, the detection of B-mode polarisation in the region of the southern sky they had monitored. Note the swirling pattern of polarisation which is the signature of B-modes, as opposed to the starburst pattern of other kinds of polarisation.

Cosmic background radiation B-modes from BICEP2

But, not so fast, other researchers cautioned. The risk in doing “science by press release” is that the research is not subjected to peer review—criticism by other researchers in the field—before publication and further criticism in subsequent publications. The BICEP2 results went immediately to the front pages of major newspapers. Here was direct evidence of the birth cry of the universe and confirmation of a theory which some argued implied the existence of a multiverse—the latest Copernican demotion—the idea that our universe was just one of an ensemble, possibly infinite, of parallel universes in which every possibility was instantiated somewhere. Amid the frenzy, a few specialists in the field, including researchers on competing projects, raised the question, “What about the dust?” Dust again! As it happens, while gravitational radiation can induce B-mode polarisation, it isn’t the only thing which can do so. Our galaxy is filled with dust and magnetic fields which can cause those dust particles to align with them. Aligned dust particles cause polarised reflections which can mimic the B-mode signature of the gravitational radiation sought by BICEP2.

The BICEP2 team was well aware of this potential contamination problem. Unfortunately, their telescope was sensitive only to one wavelength, chosen to be the most sensitive to B-modes due to primordial gravitational radiation. It could not, however, distinguish a signal from that cause from one due to foreground dust. At the same time, however, the European Space Agency Planck spacecraft was collecting precision data on the cosmic background radiation in a variety of wavelengths, including one sensitive primarily to dust. Those data would have allowed the BICEP2 investigators to quantify the degree their signal was due to dust. But there was a problem: BICEP2 and Planck were direct competitors.

Planck had the data, but had not released them to other researchers. However, the BICEP2 team discovered that a member of the Planck collaboration had shown a slide at a conference of unpublished Planck observations of dust. A member of the BICEP2 team digitised an image of the slide, created a model from it, and concluded that dust contamination of the BICEP2 data would not be significant. This was a highly dubious, if not explicitly unethical move. It confirmed measurements from earlier experiments and provided confidence in the results.

In September 2014, a preprint from the Planck collaboration (eventually published in 2016) showed that B-modes from foreground dust could account for all of the signal detected by BICEP2. In January 2015, the European Space Agency published an analysis of the Planck and BICEP2 observations which showed the entire BICEP2 detection was consistent with dust in the Milky Way. The epochal detection of inflation had been deflated. The BICEP2 researchers had been deceived by dust.

The author, a founder of the original BICEP project, was so close to a Nobel prize he was already trying to read the minds of the Nobel committee to divine who among the many members of the collaboration they would reward with the gold medal. Then it all went away, seemingly overnight, turned to dust. Some said that the entire episode had injured the public’s perception of science, but to me it seems an excellent example of science working precisely as intended. A result is placed before the public; others, with access to the same raw data are given an opportunity to critique them, setting forth their own raw data; and eventually researchers in the field decide whether the original results are correct. Yes, it would probably be better if all of this happened in musty library stacks of journals almost nobody reads before bursting out of the chest of mass media, but in an age where scientific research is funded by agencies spending money taken from hairdressers and cab drivers by coercive governments under implicit threat of violence, it is inevitable they will force researchers into the public arena to trumpet their “achievements”.

In parallel with the saga of BICEP2, the author discusses the Nobel Prizes and what he considers to be their dysfunction in today’s scientific research environment. I was surprised to learn that many of the curious restrictions on awards of the Nobel Prize were not, as I had heard and many believe, conditions of Alfred Nobel’s will. In fact, the conditions that the prize be shared no more than three ways, not be awarded posthumously, and not awarded to a group (with the exception of the Peace prize) appear nowhere in Nobel’s will, but were imposed later by the Nobel Foundation. Further, Nobel’s will explicitly states that the prizes shall be awarded to “those who, during the preceding year, shall have conferred the greatest benefit to mankind”. This constraint (emphasis mine) has been ignored since the inception of the prizes.

He decries the lack of “diversity” in Nobel laureates (by which he means, almost entirely, how few women have won prizes). While there have certainly been women who deserved prizes and didn’t win (Lise Meitner, Jocelyn Bell Burnell, and Vera Rubin are prime examples), there are many more men who didn’t make the three laureates cut-off (Freeman Dyson an obvious example for the 1965 Physics Nobel for quantum electrodynamics). The whole Nobel prize concept is capricious, and rewards only those who happen to be in the right place at the right time in the right field that the committee has decided deserves an award this year and are lucky enough not to die before the prize is awarded. To imagine it to be “fair” or representative of scientific merit is, in the estimation of this scribbler, in flying unicorn territory.

In all, this is a candid view of how science is done at the top of the field today, with all of the budget squabbles, maneuvering for recognition, rivalry among competing groups of researchers, balancing the desire to get things right with the compulsion to get there first, and the eye on that prize, given only to a few in a generation, which can change one’s life forever.

Personally, I can’t imagine being so fixated on winning a prize one has so little chance of gaining. It’s like being obsessed with winning the lottery—and about as likely.

In parallel with all of this is an autobiographical account of the career of a scientist with its ups and downs, which is both a cautionary tale and an inspiration to those who choose to pursue that difficult and intensely meritocratic career path.

I recommend this book on all three tracks: a story of scientific discovery, mis-interpretation, and self-correction, the dysfunction of the Nobel Prizes and how they might be remedied, and the candid story of a working scientist in today’s deeply corrupt coercively-funded research environment.

Keating, Brian. Losing the Nobel Prize. New York: W. W. Norton, 2018. ISBN 978-1-324-00091-4.

Here is a one hour talk by the author about the BICEP2 experience and the Nobel Prize.

This is the BICEP2 press conference on March 17, 2014, announcing the discovery of B-mode polarisation in the cosmic microwave background radiation.

What do you do after losing the Nobel prize?  In this April, 2016 (much) more technical talk at the SETI Institute, Brian Keating describes post-BICEP2 research aimed at using the cosmic background radiation to explore other aspects of the early universe including whether the universe has an inherent chirality (left- or right-handedness).  (The preview image for this video looks like it’s broken, but if you click the play button it plays correctly, at least for me.)

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Total Lunar Eclipse: Now that’s a dark one!

On the night of July 27, 2017 (as reckoned in Universal Time, as we use at Ratburger.org), the longest total lunar eclipse of the 21st century occurred.  As I am writing this, the total eclipse is just about to end.  The eclipse is not visible in the Western Hemisphere.

Total lunar eclipse: 2018-07-27, mid-eclipse

At mid-eclipse, the Moon had just risen above the trees on the southwest horizon at Fourmilab.  This is easily the darkest eclipse I have ever seen (I missed the super-dark one in the early 1960s, but I have seen many since then).  The Moon was easily observed, but no detail was obvious and only the edge of the disc was well-distinguished.  Auto-focus with a camera was impossible, as was manual focus since the image was too dark to see adequately in the DSLR finder—I had to “bracket” manual focus and hope I’d get it right on one of the shots.  Obtaining a useful image required an ISO setting of 1600 and an exposure time of 1/3 second at the f/5.6 maximum aperture of the zoom lens at 300 mm focal length.  I have processed the above in-camera JPEG image to approximate the visual impression of the eclipsed Moon (the camera got the intensity about right, but over-saturated the colours).

This eclipse was so long (totality around 103 minutes) because the Moon passed almost directly through the centre of the Earth’s shadow while it was, simultaneously, near apogee, causing it to appear small compared to the size of the shadow.  Since the entire Moon was as deep as possible within the shadow, this explains the darkness of the eclipse.  Other factors affecting the brightness of a lunar eclipse are the weather around the limb of the Earth during the eclipse, the presence of particulates from volcanic eruptions in the atmosphere, and possibly solar activity: these differ from eclipse to eclipse and cannot be reliably predicted.

By coincidence, Mars is simultaneously at perihelion and in opposition at the same time as the eclipse.  This only happens every 25,000 years.

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March Equinox 2018

Equinox: 2018-03-20 16:15 UTCThe March equinox occurs this year at 16:15 UTC on March 20.  This is the moment when the subsolar point crosses the equator headed north.  The line of day and night as seen on a map as above (produced by Earth and Moon Viewer using NASA imagery with snow and ice cover representative of March) is vertical, indicating that day and night are of equal duration everywhere on Earth.  The terminator (day/night line, not killer robots from the future) appears to curve near the poles because of the projection of the spherical Earth onto a flat map.  Here is a view of the Earth above the terminator at the moment of equinox.

Terminator at equinox: 2018-03-20 16:15 UTC

Astronomers reckon sidereal time (time measured by the positions of the fixed stars as opposed to the Sun) as starting at the March equinox.  Due to precession, the date of the equinox, measured in absolute terms by Julian date, changes slowly over time, completing one full revolution every 26,000 years.  The date and time of the equinox measured by civil calendars varies from year to year and can occur on March 19, 20, or 21.  This is due to slippage caused by leap year adjustment in the Gregorian calendar.

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TOTD 2018-01-10: Natural Philosophy, Then and Now

William Herschel (1738–1822) wrote:

In this great celestial creation, the catastrophy of a world, such as ours, or even the total dissolution of a system of worlds, may possibly be no more to the great Author of Nature, than the most common accident in life with us, and in all probability such final and general Doomsdays may be as frequent there, even as Birthdays or mortality with us upon the earth. This idea has something so cheerful in it, that I know I can never look upon the stars without wondering why the whole world does not become astronomers; and that men endowed with sense and reason should neglect a science they are naturally so much interested in, and so capable of enlarging their understanding, as next to a demonstration must convince them of their immortality, and reconcile them to all those little difficulties incident to human nature, without the least anxiety.

All this vast apparent provision in the starry mansions seem to promise: What ought we then not to do, to preserve our natural birthright to it and to merit such inheritance, which alas we think created all to gratify alone a race of vain-glorious gigantic beings, while they are confined to this world, chained like so many atoms to a grain of sand.

There speaks the eighteenth century. But Steven Weinberg says, “The more the universe seems comprehensible, the more it also seems pointless.”  If Weinberg is speaking for the twentieth century, then I prefer the eighteenth.

Freeman Dyson, “Time without end: Physics and biology in an open universe”, Rev. Mod. Phys., Vol. 51, No. 3 (July 1979), pp. 447–460.

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