2017 Nobel Prize in Physics

2017 Nobel Prize in Physics[1]

Rainer Weiss, a professor at the Massachusetts Institute of Technology, and Kip Thorne and Barry Barish, both of the California Institute of Technology, were awarded the Nobel Prize in Physics on Tuesday for the discovery of ripples in space-time known as gravitational waves, which were predicted by Albert Einstein a century ago but had never been directly seen.

From left: Rainer Weiss, Barry Barish and Kip Thorne, the architects and leaders of LIGO, the Laser Interferometer Gravitational-wave Observatory. Credit Molly Riley/Agence France-Presse — Getty Images

In announcing the award, the Royal Swedish Academy called it “a discovery that shook the world.”

That shaking happened in February 2016, when an international collaboration of physicists and astronomers announced that they had recorded gravitational waves emanating from the collision of a pair of massive black holes a billion light years away, it mesmerized the world. The work validated Einstein’s longstanding prediction that space-time can shake like a bowlful of jelly when massive objects swing their weight around, and it has put astronomers on intimate terms with the deepest levels of physical reality, of a void booming and rocking with invisible cataclysms.

Why Did They Win?

Dr. Weiss, 85, Dr. Thorne, 77, and Dr. Barish, 81, were the architects and leaders of LIGO, the Laser Interferometer Gravitational-wave Observatory, the instrument that detected the gravitational waves, and of a sister organization, the LIGO Scientific Collaboration, of more than a thousand scientists who analyzed the data.

Dr. Weiss will receive half of the prize of 9 million Swedish Krona, or more than $1.1 million, and Dr. Thorne and Dr. Barish will split the other half.

Einstein’s General Theory of Relativity, pronounced in 1916, suggested that matter and energy would warp the geometry of space-time the way a heavy sleeper sags a mattress, producing the effect we call gravity. His equations described a universe in which space and time were dynamic. Space-time could stretch and expand, tear and collapse into black holes—objects so dense that not even light could escape them. The equations predicted, somewhat to his displeasure, that the universe was expanding from what we now call the Big Bang, and it also predicted that the motions of massive objects like black holes or other dense remnants of dead stars would ripple space-time with gravitational waves.

These waves would stretch and compress space in orthogonal directions as they went by, the same way that sound waves compress air. They had never been directly seen when Dr. Weiss and, independently, Ron Drever, then at the University of Glasgow, following work by others, suggested detecting the waves by using lasers to monitor the distance between a pair of mirrors. In 1975, Dr. Weiss and Dr. Thorne, then a well-known gravitational theorist, stayed up all night in a hotel room brainstorming gravitational wave experiments during a meeting in Washington.

Dr. Thorne went home and hired Dr. Drever to help develop and build a laser-based gravitational-wave detector at Caltech. Meanwhile, Dr. Weiss was doing the same thing at M.I.T.

The technological odds were against both of them. The researchers calculated that a typical gravitational wave from out in space would change the distance between the mirrors by an almost imperceptible amount: one part in a billion trillion, less than the diameter of a proton. Dr. Weiss recalled that when he explained the experiment to his potential funders at the National Science Foundation, “everybody thought we were out of our minds.”

The foundation, which would wind up spending $1 billion over the next 40 years on the project, ordered the two groups to merge, with a troika of two experimentalists, Drs. Weiss and Drever, and one theorist Dr. Thorne, running things. The plan that emerged was to build a pair of L-shaped antennas, one in Hanford, Wash., and the other in Livingston, La., with laser light bouncing along 2.5-mile-long arms in the world’s biggest vacuum tunnels to monitor the shape of space.

In 1987, the original three-headed leadership of Drs. Weiss, Drever and Thorne was abandoned for a single director, Rochus Vogt of Caltech. Dr. Drever was subsequently forced out of the detector project. But LIGO still foundered until Dr. Barish, a Caltech professor with a superb pedigree in managing Big Science projects, joined in 1994 and then became director. He reorganized the project so that it would be built in successively more sensitive phases, and he created a worldwide LIGO Scientific Collaboration of astronomers and physicists to study and analyze the data. “The trickiest part is that we had no idea how to do what we do today,” he commented in an interview, giving special credit to the development of an active system to isolate the laser beams and mirrors from seismic and other outside disturbances.

“Without him there would have been no discovery,” said Sheldon Glashow, a Nobel Prize-winning theorist now at Boston University.

The most advanced version of LIGO had just started up in September 2015 when the vibrations from a pair of colliding black holes slammed the detectors in Louisiana and Washington with a rising tone, or “chirp,” for a fifth of a second.

It was also the opening bell for a whole new brand of astronomy. Since then LIGO (recently in conjunction with a new European detector, Virgo) has detected at least four more black hole collisions, opening a window on a new, unsuspected class of black holes, and rumors persist of even more exciting events in the sky.

“Many of us really expect to learn about things we didn’t know about,” Dr. Weiss said (October 3, 2017).

Who Are the Winners?

Dr. Weiss was born in Berlin in 1932 and came to New York by way of Czechoslovakia in 1939. As a high school student, he became an expert in building high-quality sound systems and entered M.I.T. intending to major in electrical engineering. He inadvertently dropped out when he went to Illinois to pursue a failing romance. After coming back, he went to work in a physics lab and wound up with a Ph.D. from M.I.T.

Dr. Thorne was born and raised in Logan, Utah, receiving a bachelor’s degree from Caltech and then a Ph.D. from Princeton under the tutelage of John Archibald Wheeler, an evangelist for Einstein’s theory who popularized the term black holes, and who initiated Dr. Thorne into their mysteries. “He blew my mind,” Dr. Thorne later said. Dr. Thorne’s enthusiasm for black holes is not confined to the scientific journals. Now an emeritus professor at Caltech, he was one of the creators and executive producers of the 2014 movie Interstellar, about astronauts who go through a wormhole and encounter a giant black hole in a search for a new home for humanity.

Dr. Barish was born in Omaha, Neb., was raised in Los Angeles and studied physics at the University of California, Berkeley, getting a doctorate there before joining Caltech. One of the mandarins of Big Science, he had led a team that designed a $1 billion detector for the giant Superconducting Supercollider, which would have been the world’s biggest particle machine had it not been canceled by Congress in 1993, before being asked to take over LIGO.

Subsequently, Dr. Barish led the international effort to design the International Linear Collider, which could be the next big particle accelerator in the world, if it ever gets built.

Reached by telephone by the Nobel committee, Dr. Weiss said that he considered the award as recognition for the work of about a thousand people over “I hate to say it—40 years.”

He added that when the first chirp came on Sept. 14, 2015, “many of us didn’t believe it,” thinking it might be a test signal that had been inserted into the data. It took them two months to convince themselves it was real.

In an interview from his home, Dr. Thorne said that as the resident theorist and evangelist on the project he felt a little embarrassed to get the prize. “It should go to all the people who built the detector or to the members of the LIGO-Virgo Collaboration who pulled off the end game,” he said.

“An enormous amount of rich science is coming out of this,” he added. “For me, an amazing thing is that this has worked out just as I expected when we were starting out back in the ‘80s. It blows me away that it all came out as I expected.”

Dr. Barish said he had awoken at 2:41 am in California and when the phone didn’t ring he figured he hadn’t won. Then it rang. “It’s a combination of being thrilled and humbled at the same time, mixed emotions,” he said. “This is a team sport, it gets kind of subjective when you have to pick out individuals.” LIGO, he said, is very deserving. “We happen to be the individuals chosen by whatever mechanism.”

For the National Science Foundation, the Nobel was a welcome victory lap for an investment of 40 years and about $1 billion. In a news release, France Córdova, the foundation’s director, said: “Gravitational waves contain information about their explosive origins and the nature of gravity that cannot be obtained from other astronomical signals. These observations have created the new field of gravitational wave astronomy.”

The prize was greeted with praise around the world. “Well done Sweden,” said Michael Turner, a cosmologist at the University of Chicago, adding about the result, “It took a village and 100 years to do this.”

The awarding of a Nobel to Drs. Weiss and Thorne completes a kind of scientific Grand Slam. In the last two years, along with Dr. Drever, they have shared a cavalcade of prestigious and lucrative prizes including the Kavli Prize for Astrophysics, the Gruber Cosmology Prize, the Shaw Prize in Astronomy and a Special Breakthrough Prize in Fundamental Physics. Dr. Drever died last March, and the Nobel is not awarded posthumously nor can more than three people share the prize.

[1] Dennis Overbye, “2017 Nobel Prize in Physics Awarded to LIGO Black Hole Researchers,” New York Times (October 3, 2017), accessed at https://www.nytimes.com/2017/10/03/science/nobel-prize-physics.html?_r=0 . A version of this article appears in print on October 4, 2017, on Page A8 of the New York edition with the headline: “Recording of Gravitational Waves Was ‘Discovery That Shook the World’”. Follow Dennis Overbye on Twitter: @overbye



King Tut’s Dagger

King Tut’s Dagger[1]

The blade of Tutankhamun’s ceremonial dagger, made of iron from a meteorite.

A deadly tool and the birth of a science

Howard Carter’s first words when he looked into the newly opened tomb of King Tutankhamun in 1922: “I was struck dumb with amazement, and when Lord Carnarvon, unable to stand the suspense any longer, inquired anxiously, ‘Can you see anything?’ it was all I could do to get out the words, ‘Yes, wonderful things’”

What he saw was astounding: “Strange animals, statues, and gold—everywhere the glint of gold.”

And within the wrappings of the entombed mummy, there to serve the young ruler during his journey into the afterlife, was a dagger. The dagger’s handle, topped by a crystal pommel, was intricately crafted gold. But the most remarkable part of the dagger was the 13-inch blade itself. Largely untarnished in the 3,200 years since Tut’s death, the blade was expertly worked from a metal that Egyptians would not begin to smelt for another half a millennium: iron.

It wasn’t until 2016 that a team led by Daniela Comelli of the Department of Physics at the Polytechnic University of Milan finally put the question of the blade’s provenance to rest. High concentrations of nickel and traces of cobalt left no doubt—the blade was made of iron from a meteorite.

Egyptian artifacts made from meteoritic iron date back 2,000 years before Tutankhamun, and early Egyptian texts use the term for iron to refer to some aspects of the sky. But around Tutankhamun’s time, a new word appeared. Translated literally, the rare metal was now, “iron from the sky.” As have so many civilizations, Dynastic Egyptians imagined gods and goddesses living in the heavens. A rock falling from the sky was a magical gift, fit indeed for the afterlife of a king.

Vast amounts of knowledge were lost with the decline of the ancient world. Medieval Europeans concerned themselves little with such things, until the reawakening of intellectual curiosity that began the Age of Reason. Then, in part inspired by several well-observed meteorite falls in the closing years of the 18th century, a new generation of scientists turned their attention to the strange phenomenon.

Often referred to as “thunderstones,” meteorites were thought by some to come from “igneous clouds” in the sky, sent hurtling toward the ground by lightning. The idea seemed farfetched even at the time, but it was still more believable than the ridiculous notion that they arrived from space!

Antoine Lavoisier, the great French chemist known for his many contributions to science, including the discovery of oxygen[sic][2] and the explanation of the process of combustion, wasn’t having any of it. “A stone cannot fall from the sky,” Lavoisier said. “There are no stones in the skyl”

Lavoisier might have changed his mind had he gotten the chance to study meteorites firsthand, but fate and politics intervened. Intellectuals are often among the victims of zealotry; the French Reign of Terror was no exception. Lavoisier was put to the guillotine in May 1794, nine months after the government suppressed all learned societies in France. (It took the Catholic Church more than 350 years to absolve Galileo of heresy; Lavoisier was exonerated only a year and a half after his execution. Both were Pyrrhic victories at best.)

Fortunately, intellectuals on the west side of the Atlantic were faring better at the time. Thomas Jefferson, an amateur scientist in his own right, was among those perplexed by meteorites and more than a little skeptical. In a letter to Daniel Salmon following a fall in Weston, Connecticut, in 1807, Jefferson wrote: “It may be very difficult to explain how the stone you possess came into the position in which it was found. But is it easier to explain how it got into the clouds from whence it is supposed to have fallen?”

Yet as can happen so easily at the birth of a new science, Jefferson himself was already behind the times. In 1794, the German physicist Ernst Chladni, known as the father of acoustics, had published his own ideas about meteorites. He linked meteorites and fireballs, and concluded that meteorites do fall from the sky. Chladni speculated that, given their extraordinary speed, meteorites originated not only from space, but from interstellar space. While the final suggestion was off the mark, Chladni lived to see the first two of his ideas come to be accepted by the scientific community.

The modern science of meteoritics gathered steam in the 19th century as scientists began to classify meteorites and study their compositions. With the birth of nuclear physics, meteorites became key to understanding the age and early history of the solar system. Using spectroscopy and dynamics, astronomers connected meteorites with the asteroids from which they arose. Today, meteoritics is key to theories about the processes that began in the interiors of stars and ultimately gave birth to our home world.

We’ve come a long way since ancient Egyptians hammered ceremonial daggers out of strange, heavenly metal, or Europeans spoke of thunderstones.

[1] This article derived from Jeff Hester, “King Tut’s Dagger,” Astronomy (45, 8, August 2017, p. 82). Jeff Hester is a keynote speaker, coach, and astrophysicist. Follow his thoughts at http://Jeff-hester.com.

[2] The attribution of the discovery of oxygen to Lavoisier is in error. Joseph Priestley (1733-1804) was the initial discoverer of this gas. Lavoisier discovered the role of oxygen in combustion.

Follow the Drinking Gourd

“Follow the Drinking Gourd” is an American folk song first published in 1928. The Drinking Gourd is another name for the Big Dipper asterism. Folklore has it that fugitive slaves in the United States used it as a point of reference so they would not get lost[1]. According to legend, the song was used by a conductor of the Underground Railroad, called Peg Leg Joe, to guide some fugitive slaves. While the song may possibly refer to some lost fragment of history, the origin and context remain a mystery. A more recent source challenges the authenticity of the claim that the song was used to help slaves escape to the North and to freedom.[2]

The American folksong Follow the Drinking Gourd was first published in 1928. The Drinking Gourd song was supposedly used by an Underground Railroad operative to encode escape instructions and a map. These directions then enabled fleeing slaves to make their way north from Mobile, Alabama to the Ohio River and freedom. Taken at face value, the “drinking gourd” refers to the hollowed out gourd used by slaves (and other rural Americans) as a water dipper. But here it is used as a code name for the Big Dipper star formation, which points to Polaris, the Pole Star, and North.

In the ensuing 80 years, the Drinking Gourd played an important role in the Civil Rights and folk revival movements of the 1950s and 1960s, and in contemporary elementary school education. Much of the Drinking Gourd’s enduring appeal derives from its perceived status as a unique, historical remnant harkening back to the pre-Civil War South—no other such map songs survive. But re-examining the Drinking Gourd song as history rather than folklore raises many questions. And the Drinking Gourd as it appears in roughly 200 recordings, dozens of songbooks, several award-winning children’s books and many other places is surely not “traditional.” The signature line in the chorus, “for the old man is awaitin’ for to carry you to freedom,” could not possibly have been sung by escaping slaves, because it was written by Lee Hays eighty years after the end of the Civil War. (1)

Eric Bibb gives an authentic performance of the song as we have it today. Click here to hear it.

It probably is apocryphal, but nonetheless, is easily identified with the struggle of slaves to make their way to freedom as is the song, “Swing Low, Sweet Chariot”.

One of the great singers of the 20th century was Paul Robeson, an African-American baritone. Again the words provide a metaphor for moving from slavery to freedom. “Swing Low, Sweet Chariot” may have been written by Wallis Willis, a Choctaw freedman in the old Indian Territory in what is now Choctaw County, near the County seat of Hugo, Oklahoma sometime after 1865. He may have been inspired by the Red River, which reminded him of the Jordan River and of the Prophet Elijah’s being taken to heaven by a chariot (2 Kings 2:11). Some sources claim that this song and “Steal Away” had lyrics that referred to the Underground Railroad, the freedom movement that helped black people escape from Southern slavery to the North and Canada. The river is possibly the Ohio River on the northern border of Kentucky. The river is possibly the Ohio River on the northern border of Kentucky. Click here lto hear Robeson sing the song.

Two of the great African-American singers of the 20th century were Mahalia Jackson and Nat King Cole. Again, whether or not these songs were sung in the cotton fields, the metaphor is obvious. If you will listen to Mahalia sing you can feel the depth of feeling in her gospel rendition. Click here to hear first Mahalia and then Mahalia and Nat King Cole together. Music is far more than pitch and rhythm. To sing and make a mistake is forgivable. To sing without passion is inexcusable.

I had an African-American student in Astronomy class to told me in a paper about stories his grandfather told him about seeking freedom. The stories included using the sky as a guide to get safely away from the miserable institution of slavery. So while we cannot document the origin of the songs, we can definitely recognize the desire to be free, the utility of the night sky to guide, and the deep feelings that searching for freedom that motivated the preservation and adoption of these gospel songs. Reaching for the stars is still a great metaphor.

[1] Joel Bresler. “Collection Story”. Follow the Drinking Gourd: A Cultural History. http://followthedrinkinggourd.org. Retrieved October 6, 2017

[2] Kelley, James. “Song, Story, or History: Resisting Claims of a Coded Message in the African American Spiritual ‘Follow the Drinking Gourd,. The Journal of Popular Culture (41,2, April 2008, pp. 262-80).



The Hermeneutics of Bunk

The Hermeneutics[1] of Bunk[2]

How a physicist gave postmodernism a black eye.

For anyone who pays attention to popular accounts of physics and cosmology, quantum gravity is a thing. How could it not be? Quantum gravity is the place where the two pillars of modern physics—quantum mechanics and relativity—collide head-on at the very instant of the Big Bang. The two theories, each triumphant in its own realm, just don’t play well together. If you are looking for fundamental challenges to our ideas about the universe, quantum gravity isn’t a bad place to start.

A bit over two decades ago, quantum gravity also proved to be the perfect honey trap for a bunch of academics with a taste for nonsense and an envious bone to pick with science.

In 1994, NYU physicist Alan Sokal ran across a book by biologist Paul Gross and mathematician Norman Levitt. In Higher Superstition: The Academic Left and Its Quarrels with Science[3], Gross and Levitt raised an alarm about those in the new field of “cultural studies” who were declaring that scientific knowledge, and at some level reality itself, is nothing but a social construct. Unsure whether he should take Gross and Levitt at face value, Sokal went to the library and dove into the literature that they were criticizing. When he came up for air, he was much more familiar with the postmodernist critique of science. He was also appalled at the depth of its ignorance about the subject.

Most scientists respond to such nonsense with a muttered, “good grief,” but Sokal felt compelled to do more. He decided to give postmodernists a first-hand demonstration of the destructive testing of ideas that tie science to a reality that cuts across all cultural divides.

Sokal had a hypothesis: Those applying postmodernism to science couldn’t tell the difference between sense and nonsense if you rubbed their noses in it. He predicted that the cultural science studies crowd would publish just about anything, so long as it sounded good and supported their ideological agenda. To test that prediction, Sokal wrote a heavily footnoted and deliciously absurd 39-page parody entitled, “Transgressing The Boundaries. Toward A Transformative Hermeneutics of Quantum Gravity.”[4]

The paper is worth reading just for a belly laugh. It promises “emancipatory mathematics” at the foundation of “a future post-modern and liberatory science.” “Physical ‘reality’,” it declares, “is at bottom a social and linguistic concept.” He embraces the notion, seriously proposed by some, that logic itself is invalidated by “contamination of the social” When he showed it to friends, Sokal says, “the scientists would figure out quickly that either it was a parody or I had gone off my rocker.”

Sokal submitted his paper to a trendy journal called Social Text. Understanding the importance of ego, he freely and glowingly cited work by several of the journal’s editors. For their part, the folks at Social Text were thrilled to receive Sokal’s manuscript. Here at last was a physicist who was “on their side!” After minor revisions, the paper was accepted and scheduled to appear in an upcoming special “Science Wars” edition.

The bait had been taken, but the trap had yet to be sprung. That came with a piece by Sokal in Lingua Franca[5] that appeared just after Social Text hit the stands, exposing “Transgressing the Boundaries” as the hoax it was.

Parody sometimes succeeds where reasoned discourse fails. Sokal’s little joke burst free of the ivory tower on May 18, 1996, when The New York Times ran a front-page article entitled, “Postmodern Gravity Deconstructed, Slyly.[6]” The Sokal Hoax became a hot topic of conversation around the world!

Reactions to Sokal’s article were, shall we say, mixed. The editors of Social Text were not amused, to put it mildly, and they decried Sokal’s unethical behavior. One insisted that the original paper was not a hoax at all, but that fearing reprisal from the scientific hegemony, Sokal had “folded his intellectual resolve.” It was lost on them that had they showed the paper to anyone who knew anything about science or mathematics, the hoax would have been spotted instantly.

As most scientists did: When I heard about it, I busted a gut!

I still laugh, but the Sakai Hoax carries a serious message. In addition to diluting intellectual rigor, the postmodern assault on science undermines the very notion of truth and robs scientists and scholars of their ability to speak truth to power. As conservative columnist George Will correctly observed, “the epistemology that Sokal attacked precludes serious discussion of knowable realities.” Today, from climate change denial, to the anti-vaccine movement, to the nonsensical notion of “alternative facts,” that blade is wielded on both sides of the political aisle.

Sokal gets the last word. Quoting from his 1996 Lingua Franca article, “Anyone who believes that the laws of physics are mere social conventions is invited to try transgressing those conventions from the windows of my apartment. (I live on the 21st floor.)”

[1] Hermeneutics: the branch of knowledge that deals with interpretation.

[2] See Jeff Hester, “The Hermeneutics of Bunk: How a physicist gave postmodernism a black eye,” in Astronomy (45, 7, July 2017. p. 14). Jeff Hester is a keynote speaker, coach, and astrophysicist. Follow his thoughts at Jeff-hester.com.

[3] See Paul R. Gross (1998) and Norman Levitt. Higher Superstition: The Academic Left And Its Quarrels With Science, Baltimore, MD: Johns Hopkins University Press [LCCN: 98106819]

[4] Sokal, Alan D. “Transgressing the Boundaries: Toward a Transformative Hermeneutics of Quantum Gravity,” Social Text (46/47, Spring-Summer, 1996, pp. 217-252)

[5] Sokal, Alan, “A Physicist Experiments with Cultural Studies,” Lingua Franca (6, July-August 1996, pp. 54-67).

[6] Janny Scott, “Postmodern Gravity Deconstructed, Slyly,” New York Times (May 18, 1996). Accessed at http://www.nytimes.com/1996/05/18/nyregion/postmodern-gravity-deconstructed-slyly.html.

Formation of a Black Hole

Formation of a Black Hole[1]

A supermassive black hole (SMBH) is the largest type of black hole, on the order of hundreds of thousands to billions of solar masses, and is found in the center of almost all currently known massive galaxies. In the case of the Milky Way, the SMBH corresponds with the location of Sagittarius A*.

[1] See Ástronews: How Does A Black Hole Form?” in Astronomy (45, 7, July 2017. p.15)

Volcano on the Moon?

Volcano on the Moon[1]

0n the evening of March 7, 1794, William Wilkins took a stroll up Castle Hill in Norwich, England, to see if he could spot Mercury in the evening sky. Wouldn’t you know it! Cloudy in the west. Then he looked up.

What he saw was a shock and surprise, one that stoked a mystery that has sputtered on for more than two centuries, helping to fuel tantalizing speculations about active events on our supposedly dead Moon.

Wilkins, 44, was an amateur astronomer. He had been inspired by William Herschel’s discovery of Uranus—the first new planet since antiquity, putting astronomy in the headlines (Britain triumphs over French astronomersl)—just 13 years earlier. Like Herschel, Wilkins owned a reflecting telescope rather than the more common refractor. But unlike the famous ex-musician, Wilkins hadn’t quit his day job. He was an architect, busy constructing a lighthouse with Argand lamps (oil lamps with big cylindrical wicks, the latest in high-intensity lighting). During the course of this work, he wrote “the goodness of my sight has often been remarked, in discovering vessels with the naked eye, which my companions could not discover but with the telescope.” So he described himself in a letter to the astronomy professor Rev. Samuel Vince, lest there be any doubt about what followed:

. . . respecting the phenomenon I saw in the moon, on Friday the 7th of March, a few minutes before eight o’clock . . . I had been looking for that planet [Mercury] from the Castle-hill in Norwich, but was disappointed by a clouded horizon. I mention this merely as the reason of my being led to a more particular notice of the moon . . . having lost the first object of the evening’s attention. When I saw the light speck, as shewn in the sketch [at right], I was very much surprised; for, at the instant of discovery I believed a star was passing over the moon, which on the next moment’s consideration I knew to be impossible . . . I was, as it were, rivetted to the spot . . . and took every method I could imagine to convince myself that it was not an error of sight; and two persons, strangers, passed me at the same time, whom I requested to look, and they (may be, a little more ignorant than myself) said it was a star. I am confident I saw it five minutes at least . . The whole time I saw it, it was a FIXED, STEADY LIGHT, except the moment before it disappeared, when its brightness INCREASED; but that appearance was instantaneous … I mentioned this soon afterwards to a gentleman of my acquaintance, who . . , conjectured this phenomenon to be some great volcanic convulsion in the moon, which induced me at that time to assist my memory with a sketch like what I have here sent you. I shall be obliged to you, Sir, if you will favour me with Dr. MASKELYNE’S opinion . . . .

Enter the Astronomer Royal

Wilkins’s letter went straight to the top. It appeared in the Royal Society’s Philosophical Transactions as part of an investigation by England’s Astronomer Royal, Nevil Maskelyne, titled “An Account of an Appearance of Light, like a Star, Seen in the dark Part of the Moon, on Friday the 7th of March, 1794.” Here Maskelyne writes that soon after he learned about Wilkins, his own relation Sir George Booth and his wife paid him a visit at the Royal Observatory grounds in Greenwich. Lady Booth remarked that their servant, “who is curious for a person in his situation, and fond of looking at the stars, had some time before seen something extraordinary in the moon,” When questioned by Maskelyne himself, the servant recalled that “some time ago, about six in the evening, he saw a light like a star, and as large as a middle sized star, but not so bright, in the dark part of the moon. He continued looking at it for a minute or more, during which time it kept the same light, and he then lost sight of it by going in the house.”

Maskelyne then tried to verify the time, which Lady Booth felt was later than six o’clock (around sunset). He met with a Thomas Stretton, who had also come forward. They went to where Stretton had stood in St. John’s Square, London, and Maskelyne had him point out where he had seen the Moon “with respect to the opposite house and chimnies over which she appeared.” Not the Astronomer Royal for nothing, Maskelyne describes how “with the help of a pocket compass and small wooden quadrant, I found the bearing of the place in the sky … to be 80° west of the magnetic south, or 56° west of the true south meridian, and the altitude 34°. Taking the moon’s right ascension from the nautical almanac for the 7th of March . . . with the bearing abovementioned, and the latitude of St. John’s Square taken 51° 31’,” he calculated that the observation must have been made not far from eight o’clock, “and therefore the two observations agree as nearly together as can be expected.”

Stretton must have pointed with remarkable accuracy, and Maskelyne’s pocket compass must have been a good one too. Just a 14° pointing error could result in an hour’s time error. But Maskelyne was making the most of this opportunity.

Star of the Show?

Suspiciously, an occultation of 1st-magnitude Aldebaran had begun about an hour earlier and ended a half hour earlier. The occultation was a near-grazing one. For Norfolk, as we can calculate quite precisely from our vantage in the 21st century, the star disappeared on the Moon’s dark limb at 6:57 p.m. local mean time and reappeared from behind the bright limb at 7:33 p.m. LMT. (If Norwich was still using the older system of local apparent solar time, its clocks would have read 11 minutes earlier.) A half hour after the occultation ended, Aldebaran would have been plainly visible about half a lunar diameter to the Moon’s right, off the bright limb.

But one hour earlier, Aldebaran was slowly skimming along the Moon’s dark limb—at just the correct orientation of the mystery star so carefully noted by Wilkins!

And its sudden winking out, after shining steadily for at least 5 minutes, would of course have been the occultation itself[2].

Nevertheless, Maskelyne ruled out any connection between the Aldebaran occultation and the sighting. He concluded,

I shall make no conjectures on the cause to which this extraordinary phenomenon may be attributed; but only remark, that it is probably of the same nature with that of the light seen of late years in the dark part of the moon by our ingenious and indefatigable astronomer, Dr. HERSCHEL, with his powerful telescopes, and formerly by the celebrated DOMINIC CASSINI; although this has been so illustrious as to have been visible to the naked eye, and probably equal in appearance to a star of the third magnitude.

Those Disreputable TLPs!

Scientists in the late 18th century generally lacked the sophisticated understanding of statistics that any good scientist draws upon today. The statistician Thomas Bayes had introduced Bayes Theorem two decades earlier; it is the formal way to determine, among other things, what is “too unlikely a coincidence.” But even an astronomer as illustrious as Maskelyne may not have considered his “priors.” What was the prior likelihood that, right at the time of such a remarkable and seemingly impossible sighting—if the witnesses were wrong and the time was a few minutes before 7 instead of 8 or 6—Aldebaran would have been right there along with the mystery “star”? What was the chance of such a coincidence given the rarity of bright-star occultations, much less one at just the correct place on the Moon’s limb?

And yet, Wilkins says

I was very particular in my inquiries respecting the time, and called purposely on a neighbour [a Mr. R. Bacon, publisher of one of the Norwich newspapers] to ascertain it with certainty; and found it a few minutes before eight o’clock, which I entered in my pocket journal; and on inquiry of Mrs. WILKINS, she says I left home at that time.

Cade Hill was just 50 yards from his home, so he would have wasted little time getting there and back.

At 1st magnitude, Aldebaran is six times brighter than the 3rd-magnitude light that Maskelyne estimated for the lunar event. The glare of the Moon makes a star close to it look dimmer than it really is. But it’s suspicious that none of the eyewitnesses seems to have mentioned a second star at the Moon that was at least as bright and eye-catching.

The dark limb would have been invisible to the naked eye; the Moon was a day short of first quarter (41% illuminated). So where exactly was the line between on the Moon and off the Moon? If the Moon’s brilliance made it appear a little larger than reality to the naked eye, as often happens, might one misjudge that Aldebaran was inside the dark limb, rather than on it?

Quite possibly. In 1860 the famed observer Rev. T. W. Webb published a note in the Monthly Notices of the Royal Astronomical Society describing this effect and saying that it accounted for the famed Wilkins lunar volcano:

On the same evening there was an occultation of Aldebaran, which Dr. Maskelyne thought a singular coincidence, but which would now be acknowledged as the cause of [Wilkins’s] phenomenon. . . . [T]he effect of irradiation [expansion of glare] upon an object out of focus is greater than might be supposed by those whose vision is perfect; of this I have been made aware through my own near sight, in consequence of which luminous spaces are enlarged at the expense of adjacent dark ones, to an extent which might hardly have been anticipated.

The term Transient Lunar Phenomenon (TLP) would not be invented for many years to come. Most reports of them refer to particular lunar features appearing unusually bright or hazy in a telescope. Their reality has always been questioned, and lunar astronomers today take essentially all such reports to be misobservations of features under changes of lighting (see S&T, August 2017 issue, page 52). But the decade leading up to Wilkins’s sighting was a heyday for TLP sightings, which were sometimes described outright as active lunar volcanoes. By 1794 astronomers were primed for them.

The TLP controversy, long considered nearly dead, gained a new gasp of life with a 2009 paper in The Astrophysical Journal titled “Transient Lunar Phenomena: Regularity and Reality” by Arlin Crotts. He wrote that judging from a 1968 NASA catalog of 579 TLP reports since 1540, statistics suggest that 80% were real, since 50% were seen near Aristarchus (the Moon’s brightest white spot) and approximately 16% in Plato.

Nowadays, low-light video monitoring through telescopes occasionally catches actual, brief pinpoint flashes on the Moon’s night side. These are small meteoroid strikes, and they appear at rates consistent with Earth’s known meteoroid environment. Larger ones must also happen from time to time. But these flashes of white-hot vapor are gone in a moment in the lunar vacuum. The star that Wilkins saw shone unchanged for minutes—before winking away into more than two centuries of astronomical lore and legend.

Wilkins’ Star in Your English Class

Wilkins’ star may be memorialized foreveer in Samuel Taylor Coleridge’s The Rime of the Ancient Mariner:

The stars were dim, and thick the night,
The steersman’s face by his lamp gleamed white
From the sails the dew did drip—
Till clomb above the eastern bar
The hornèd Moon, with one bright star
Within the nether tip.

And with that evil omen, the ship’s crew give the albatross-slaying Mariner a dirty look and drop dead, supernaturally.

Coleridge wrote the Ancient Mariner in 1797-98, just three or four years after the publication of Wilkins’ sighting and Maskelyne’s analysis. Coleridge was almost surely aware of these; he was an avid reader and devoured articles about every kind of natural curiosity. Maskelyne’s report in the Philosophical Transactions created a stir, prompting a lengthy summary of the sighting in the more popular British Critic—which was, like the Phil. Trans. itself, one of Coleridge’s regular reads.

[1] Andrew Livingston, “Mystery Solved? The 1794 Volcano on the Moon,” Sky and Telescope (134, 5, November 2017, pp. 30-33). Andrew Livingston sees TLPs—Toronto’s light-polluted skies—all the time. Alan MacRobert, Don Olson, David Dun-ham, David Herald, Leslie Morrison, and Tony Cook contributed to the Aldebaran investigation.

[2] “Occultation” is the state of becoming hidden or of disappearing from view. In Astronomy, it is the disappearance of a celestial body behind a closer, apparently larger celestial body.