Brueghel's Telescopes

October 13, 2009

History books generally identify the inventor of the telescope as one Hans Lippershey, an eyeglass maker in the Netherlands in the late 16th century. The story goes that Lippershey saw a couple of children playing with lenses in his shop, and overheard them exclaim that looking through the lenses made a nearby building seem larger.

Lippershey experimented a bit further, and built a device he called a "looker," using a convex objective lens and a concave eyepiece. Galileo snagged an early version of the telescope as it spread through Western Europe, and improved the design to make the first observations of the moons of Jupiter, among other momentous findings.

But Johannes Kepler suggested the instrument could be improved even more in 1611 by using a convex eyepiece, resulting in a wider field of view. Nor was it necessary any longer to plate the eyepiece so close to the eye of the observer. The only disadvantage: the resulting image is inverted. Astronomers adapted accordingly. The first Keplerian telescopes were believed to appear around 1631.

Of course, there is evidence that Lippershey may not have been the first to build a telescope after all. His 1608 patent application was denied because the knowledge that combinations of lenses could magnify objects was already well known by that time. And now Kepler's own contribution to the development of the telescope is coming into question, according to astrophysicists at the Instituto Nazionale di Astrofisica in Trieste. The evidence can be found in a painting by a Flemish artist named Jan Brueghel the Elder, which depicts a telescope of Keplerian design even though the canvas was painted a good 15 years before its supposed invention.

Paolo Molaro and Pierluigi Selvelli have studied five paintings by Brueghel depicting telescopes, and maintain the artist made the first such representation of the telescope in his work, "Extensive Landscape with View of the Castle of Mariemont." Brueghel was court painter to Archduke Albert VII of Habsburg, and it just so happens that Lippershey gave one of his earliest telescopes to Albert. Molaro and Selvelli believe the telescope in the painting is, in fact, that particular instrument.

Another painting, "The Allegory of Sight," depicts a telescope that seems very much to be of Keplerian design -- except the canvas dates from 1617, well before the first Keplerian telescopes supposedly were built. Molaro and Selvelli base their conclusion on the length of the painted instrument -- is is longer than the earlier Galilean designs, just like Kepler's telescopes -- and the size of the eyepiece, designed to limit how close the eye can be brought to the eyepiece lens.

It's always a bit risky to draw scientific conclusions from works of art: all artists take liberties with their subjects when creating a painting, after all. But sometimes historical paintings can offer tantalizing clues, particularly when so little is known about an era. I guess we'll have to wait and see if art (or science) historians manage to dig up some corroborating evidence to support Molaro and Selvelli's hypothesis. In the meantime, it certainly makes for an intriguing premise.

"All You Need is the Rocket Experience..."

June 23, 2009

Next month marks the 40th anniversary of the Apollo 11 moon landing, when NASA astronauts Neil Armstrong and Buzz Aldrin boarded the lunar module and took one small step for man on the surface of the moon. There are lots of activities planned to commemorate this historic event, but Aldrin's taken a distinctly quirkier approach: he's made a hip-hop video with Snoop Dogg and Talib Kweli (of Black Star fame), with the proceeds going to benefit various space exploration foundations.

Even better, Funny or Die got into the act and made a tongue-firmly-in-cheek "Behind the Scenes" video about the making of "Rocket Experience," featuring numerous rappers giving Aldrin a few tips, and talking about the moon landing's impact on their lives. (Check out Snoop Dogg's lyrical rap tribute to Buzz at the very end.) Per Kweli: "Buzz Aldrin got his bars up!"

Making of Buzz Aldrin's Rocket Experience w/ Snoop Dogg and Talib Kweli from Buzz Aldrin

And now, for your listening pleasure, here's Buzz Aldrin -- a.k.a."Doc Rendezvous" -- in the final video cut for "Rocket Experience," directed by none other than McG (Terminator: Salvation):

Buzz Aldrin's Rocket Experience from Buzz Aldrin

Dream a Little Dreaming

June 05, 2009

England has its Stonehenge, and Australia has Wurdi Youang, an egg-shaped ring of stones just outside of Geelong. It was built by the Wathaurung people -- long before the arrival of European settlers --and measures a good 50 meters across. And as with Stonehenge, no record exists of why the ring might have been built, or how it was used. But according to a new paper appearing this week on the arXiv, it might just be an example of Australia's earliest form of astronomy.

Aboriginal mythology is largely associated with the "Dreaming," an ancestral world of spirits who are still manifest in the night skies. Certain nomadic Aboriginal Australians apparently used the sky as a kind of calendar to determine when it was time to on to a new site, for example. And the various Aboriginal cultures across the huge continent share some common threads in their mythology. For instance, there is a female sun warming the land, and a male moon who starts out slim (the crescent moon) and grows fat as he ages (full moon), then dies to begin the lunar cycle again (new moon).

A cultural historian named John Morieson noticed a few years ago that, when viewed from three of the most prominent stones, the smaller outlying stones corresponded rather well with the position of the setting sun during equinoxes and solstices. Enter astrophysicist and astronomer Ray Norris, who confirmed those observations and co-authored the new paper with his colleague Duane Hamacher at MacQuarie University in Sydney.

Granted, the hypothesis has its skeptics, and even Norris insists that other similar sites with stone rings are needed before it becomes truly viable. For instance, the placement of the stones is accurate enough to within a few degrees, but the alignment could very well have occurred by chance. "The problem with all of this stuff is that you are never 100% certain -- are we constructing something with our 21st century minds that wasn't actually intended by the people who built it?" Norris admits, but believes there is sufficient evidence regarding Wurdi Youang indicating the tribe did know the astronomical significance of those directions.

Less convincing, according to Norris, is the arrangement of stones known as Ngaut Ngaut, located on the banks of the Murray river just north of Adelaide. It, too, has some hints of astronomical connections, most notably engraved images of the Sun and Moon, plus a series of mysterious dots and lines carved into the rock, believed to show the "cycles of the moon." The problem is that Norris and others haven't had much luck cracking this ancient symbolic "code." Until they do, the "evidence" is circumstantial at best.

Nonetheless, the entire question of Aboriginal astronomy is fascinating -- sufficiently so that Norris and a few colleagues from various disciplines have started the Aboriginal Astronomy Project to answer a few key questions:

(1) Are there cultures in which the astronomy is a central feature rather than lying on the periphery?

(2) Is there evidence that the complex motions of the sky have been recorded either verbally or in rock art or stone arrangements? and

(3) Is there evidence that transient phenomena such as supernovae, comets and meteors were recording?

The answers to those questions are still pending, but I like the idea of an investigation involving astronomers, archaeologists, anthropologists, and some of the indigenous peoples themselves (a few have appeared as co-authors on the group's journal publications). And the Melbourne Planetarium is apparently working with Norris on a new presentation about indigenous astronomy. If the group's working hypothesis is eventually borne out, that would make Aboriginal Australians -- already the world's oldest culture, dating back some 50,000 years -- the world's earliest astronomers.

Photos: (top) Arrangement of stones at Wurdi YouangT. (bottom) Engravings at Ngaut Ngaut. Source: Aboriginal Astronomy Project.

R.I.P.: Venetia Phair

May 15, 2009

Fans of everyone's favorite erstwhile planet, Pluto, mourned the passing on May 5th of Venetia Phair, nee Burney, at the age of 90. Phair gave the little pseudo-planet its name way back when in 1930, when it was first discovered by Clyde Tombaugh. She was only 11 then -- Tombaugh was merely 24 -- and living in Oxford, England, with her grandfather, a retired librarian at the famed Bodleian. She had no idea her name would continue to stump avid Trivial Pursuit players 50+ years later.

It's a sweet story, actually, and has nothing to do with the Disney character, Pluto (also introduced in 1930). Her grandfather, Falconer Madan, read her the news story of the planet's discovery over breakfast on the morning of March 14, 1930, which mentioned the planet had yet to be named. Young Venetia was fascinated at the time with the planets in the solar system. She told BBC News in 2006, "At school we used to play games in the university park, putting... lumps of clay at the right distance from each other to represent the distances of the planets from the sun."

She also loved Greek and Roman mythology. In fact, at the time of the discovery, she was reading The Age of Fable by Thomas Bullfinch -- clearly a most precocious child. She told her grandfather she thought the new planet should be named Pluto, after the Roman god of the underworld. (The first two letters are also the same as the initials of Percival Lowell, who with William Pickering first predicted the existence of planet past Neptune.) It helps to have good connections: Madan's brother had suggested that the moons around Mars be named Phobos and Deimos in 1878, so naming celestial objects kind of ran in the family.

Madan also knew Herbert Hall Turner, a professor of astronomy at Oxford, and dropped a note for the professor with Venetia's suggestion. Turner telegraphed the proposed name to the Lowell Observatory. And on May 1, Pluto became the official name of the ninth planet in the solar system. Venetia's grandfather rewarded her with five-pound note.

That little girl grew up to study mathematics at Newnham College in Cambridge, became a chartered accountant during World War II, and then taught economics until the mid-1980s. In retirement, she volunteered with the Friends of Epsom Hospital. In the end, she outlived the planet she named; Pluto was demoted to dwarf planet status in 2006.

Few people know the name Venetia Phair today. But her passing deserves to be marked anyway, if only to inspire other 11-year-old girls that they, too, can make their mark on science history.

Galileo: Awesome Dude

April 08, 2009

Galileo Galilei is known for many things: dropping items from atop the leaning tower of Pisa, for example, to demonstrate that all objects fall at the same rate, regardless of their mass. That's actually an apocryphal story: he often used the notion as an illustrative example, but there's no record he ever did the actual experiment. (He did roll balls down a gentle incline to measure their acceleration, using his pulse as a time-keeper.)

He's also famous for espousing the Copernican model of the solar system -- the one where the Earth and other planets revolve around the sun, rather than the Ptolemaic model wherein everything revolved around the Earth -- and being convicted of heresy by the Inquisition in 1633 for his trouble. He spent the rest of his life under house arrest, and his condemnation wasn't revoked officially until October 31, 1992, by Pope John Paul II. This has made Galileo the patron saint of misunderstood science crackpots everywhere, who fancy themselves equally persecuted by a close-minded scientific "establishment." Personally, I prefer the take of online comic Medium Large, which views Galileo as a suave crime-fighting  man-about-town:

 

Well, maybe the world isn't ready yet for a TV series based on a crime-fighting 17th century astronomer -- are you listening, Les Moonves? -- but the world is definitely ready for a new documentary celebrating the International Year of Astronomy, 400 years of the Telescope, airing on PBS this Friday, April 10 (local airtimes may vary). The film celebrates four centuries of discoveries about our universe made possible by the the telescope, from Galileo to the most cutting-edge instruments exploring the outermost frontiers of scientific knowledge of the cosmos.

And that's not all. The cinematography is breath-taking and uses 35 mm RED camera technology. I don't know what the acronym stands for, but it means the film was recorded at a whopping 4520 x 2540 pixels per frame -- five times the resolution of high-definition TV. But wait! There's more! It's narrated by Neil de Grasse Tyson. Now how much would you pay? And yet it's free, thanks to the glory of public television. There is no bad here.

Tell your friends, even those who might not be all that keen on science. Astronomy is always a crowd-pleaser. Then, maybe more people will be able to correctly identify another of Galileo's breakthrough discoveries: three of Jupiter's moons. That's how he became a Copernican the first place, rightly reasoning that if a planet like Jupiter could have its own orbiting moons, then Earth could not possibly be the center of the entire universe. He published his observation in Sidereus nuncius (Starry Messenger) in March 1610, doing his small part to topple Ptolemy once and for all.

Galileo = Awesome Dude. Pass it on.

Comic: The always excellent Medium Large.

Now Where Did I Put That Atomic Cannon?

April 01, 2009

It's a fairly well-accepted maxim that just as much as science inspires writers of science fiction, so, too, does truly inventive sci-fi inspire scientists in turn. Back in 1865, Jules Verne published one of the earliest science fiction novels, From the Earth to the Moon, set  few years after the end of the US Civil War. The central characters are all veterans who are members of the Baltimore Gun Club, now put out to pasture and bored silly now that they have no excuse to randomly blow things up. They decide to build a gigantic cannon with enough propulsion power to launch a projectile to the moon.

Preposterous, you say? Well, sure, from a 21st century perspective, but at the time it probably sounded perfectly plausible, and this being fiction, the plucky members of the Baltimore Gun Club succeed in launching three men into space with their giant cannon, winning a bet with a rival captain in the process. Verne foresaw the space race long before then-president John F. Kennedy made landing on the moon a top national priority. Not surprisingly, Verne's novel inspired more than one young boy to become a rocket scientist, including J. Robert Goddard, inventor of the first liquid-fuel rocket. 

It takes an enormous amount of energy, and thus fuel, to launch a NASA rocket into space, and a great deal of research in the 1950s and 1960s focused on finding more powerful means of propulsion. One such program was Project Orion, wherein scientists labored to build a spacecraft powered by a nuclear bomb. I'm sure the astronauts were just thrilled by the prospect of strapping themselves into a long metal tube sitting on top of a nuclear bomb.

The project was canceled in 1964 after concerns were raised about the inevitable collateral damage that would result from even just one such launch. We're not just talking about the astronauts here: the inevitable fallout would have killed any number of animal species, vegetation, and oh yes, human beings who happened to be in the vicinity of the blast.

Still, in a recent post, sci-fi author/blogger Karl Schroeder resurrects the notion, maintaining that Project Orion was perfectly feasible. He cites a couple of blog posts over at Next Big Future estimating that it would be possible to calibrate an Orion-type spacecraft so that there would only be a dozen or so deaths per launch. Perhaps that's an acceptable risk for the folks at Next Big Future, but count me among the more squeamish sorts who balk at voluntarily sacrificing other people's lives.

Schroeder seems to share my moral misgivings, and proposes his own cutting-edge propulsion device: an atomic cannon, although he prefers to call it "the Verne gun," since it employs the same basic premise as the Baltimore Gun Club's gigantic cannon. Per Schroeder:

The principle is the same as Verne's original idea, but using modern technology: you set off a nuclear charge underground where the blast, heat, radiation and fallout can all be contained, and use Orion-type technology to direct its energy into orbiting a very big, very heavy spacecraft. This vessel would experience hundreds to thousands of g's of acceleration--you couldn't put humans in it. But ... a 10 megaton bomb could put 280,000 tons into orbit with zero radiation escape into the biosphere.

Sounds good in theory, at least, although making such a spacecraft work in a practical setting is no small feat. But all progress begins with inspiring men to dream and aim for the stars -- or in Verne's case, the moon. We reached the moon decades ago. Perhaps Schroeder and his cohorts will be among those who inspire the next wave of space exploration... even if the Verne gun turns out to be a bust, who knows what it will inspire to replace it?

Image: Karl Schroeder.

Champagne Supernova

January 11, 2009

"Some day you will find me
Caught beneath the landslide
In a champagne supernova in the sky."
   -- Oasis, "Champagne Supernova"

Nobody pens an inscrutable lyric like fraternal singer/songwriter duo Noel and Liam Gallagher, chief members of the band Oasis, who scored a mega-hit in the 1990s with the seven-plus-minute rock ballad, "Champagne Supernova." Even Noel, who wrote the lyrics, has admitted he has no idea what the song is about, other than some vague notion that perhaps it has something to do with reincarnation. The creative mind works in mysterious ways. But it's haunting, yet catchy, and comes with a moodily psychedelic video to boot, with lots of Emo-brooding by vocalist Liam, and rail-thin models attempting some semblance of dance. (In their defense, it is not the most danceable tune.)

The exact origin of Type 1A supernovae is equally mysterious, although astrophysicists have a few ideas about what sorts of star systems are most likely to explode as supernovae. Type 1A supernovae are particularly important in astronomy, astrophysics and cosmology because they serve as "standard candles" (distance markers) for measuring things like how fast our universe is expanding. (Answer: it's expanding at an accelerating rate.)

But there's always a chance of errors in those calculations, particularly if more distant supernovae differ from the closer ones. Knowing the initial conditions that set off Type 1A supernovae would enable astronomers to include any needed corrections. The result: even better measurements.

The leading candidates are recurrent novae. Ordinarily, a nova is a double star, where one star sloughs off matter onto its partner white dwarf star. This excess material gradually builds up on the white dwarf's surface until it triggers a runaway thermonuclear chain reaction -- think an explosion equivalent to a thousand-billion-billion hydrogen bombs, per Bradley Schaefer of Louisiana State University, who spoke at last week's AAS meeting in Long Beach.

This happens once every 10,000 years or so. In comparison, recurrent novae have multiple eruptions every century. Al you need is a binary system with a very high mass white dwarf star, and matter falling onto it very quickly to eventually have the white dwarf collapse ("caught beneath the landslide") and turn into a Type 1A supernova. Suddenly those Oasis lyrics seem eerily accurate, don't they? Maybe a Type 1A supernova could be viewed as the reincarnation of a recurrent novae. Or something. Metaphorical song lyrics aren't meant to be exact.

Anyway, Schaefer wanted to know if there are enough recurrent novae in the universe to account for the number of Type 1A supernovae observed, suspecting that perhaps many objects classified as ordinary novae were, in fact, recurrent novae. He turned to archival data -- old photographic plates -- to test that theory. "Archival data is the only way to see the long-term behavior of stars, unless you want to keep watch nightly for the next century," he says, although a 100-year-vigil would be a fantastic way to torture one's least favorite grad students. (As it happens, only one out of 25 novae are ever spotted, which Shaefer believes provides an opportunity for amateur astronomers to monitor the sky with digital cameras and help discover missing eruptions.)

Schaefer opted to bet on history. He combed through the two primary archives at Harvard College Observatory in Boston, and the headquarters of the American Association of Variable Star Observers (AAVSO) in Cambridge to find out, plus a couple of others (just to be thorough). Harvard alone has a collection of half a million old sky photos, with 1000-3000 shots of each star dating back to 1890. Among other discoveries, Schaefer's LSU colleague, Ashley Pagnotta, thought that one classical nova in particular, Nova Ophiuci 1998, had all the characteristics for a recurrent novae. Sure enough, one of the Harvard plates revealed an earlier eruption in 1900. It is, indeed, a recurrent novae.

Schaefer estimates that the total number of recurrent novae in the Milky Way is probably around 10,000 -- high enough to account for all the observed Type 1A supernovae. Who says those dusty old photographic plates are no longer useful?

The massive task of combing through all that historical data also yielded the first prediction of which star is likely to go nova in a particular year. There's a star system known as U Scorpii that should erupt any month now, with its very own worldwide collaboration in place to record the event in various regimes (x-ray, ultra-violet, optical, and infrared wavelengths). If that prediction pans out, astronomers will be able to pinpoint other similar events -- and keep massing more and better information about these mysterious objects.

Photos: (top) Multi-wavelength (x-ray, infrared and optical) compilation image of Kepler's supernova remnant, SN1604. Source: Chandra X-Ray Observatory (public domain). (bottom) Plate AM505 from the collection at Harvard University, showing the 1900 eruption of Nova Ophiuci 1998, predicted to be a recurrent nova with multiple eruptions every century. Credit: Ashley Pagnotta, Louisiana State University. Used with permission.

The 'Scopes Have Eyes

January 05, 2009

We're back, fresh from a nice long holiday break and ready to sample the wonders the universe has to offer in 2009. It just so happens that this is the start of the official International Year of Astronomy, a joint effort by the International Astronomical Union and UNESCO around the theme, "The Universe: Yours to discover!" It's a huge endeavor, with thousands of sponsored events all year long, including "The Cosmic Diary" -- a group blog initiative with 50 bloggers from 35 countries -- and daily podcasts from "365 Days of Astronomy." You can find a complete list of event highlights here.

Sadly, I will not be flying to Paris later this month for the official Opening Ceremony, but I thought it might be nice to honor one critical development in particular: the rise of adaptive optics to correct various optical aberrations that typically plague even highly advanced telescopes. Telescopes gather light from the stars, but before it reaches the instrument (at least here on earth), the light first must pass through our atmosphere, and all those layers of air with varying temperatures and densities causes that light to become distorted. In fact, that's why stars seem to twinkle instead of just appearing as a sharp pinpoint of light.

An adaptive optics system corrects the "wavefronts" of light, basically straightening the paths to improve resolution and contrast. The result is brighter, clearer images. Current systems use a wavefront sensor to sample the light collected by a telescope's primary mirror and send that data to a computer. The computer in turn controls a deformable mirror that can be adjusted to cancer out any atmospheric distortions. SUre, you could send a telescope into space -- the Hubble Space Telescope hasn't done too badly -- but it's expensive to do so. And many scientists believe that ground-based telescopes with cutting-edge adaptive optics could very well produce images of even better resolution than Hubble (at least in the infrared region of the spectrum, when is where AO works best). The benefits of AO increase dramatically with telescope size, because more light can be collected. 

But adaptive optics aren't just for telescopes anymore. The human eye -- especially the cornea and lens -- can also distort wavefronts and give rise to those pesky aberrations that plague telescopes as well. Eye doctors use instruments called opthalmocopes to image their patients' eyes, but aberrations often make it more difficult to spot developing problems. But scientists have now figured out how to incorporate adaptive optics and micro-electro-mechanical systems (MEMS) technology to build a new kind of opthalmoscope capable of imaging individual retinal cells.

The system -- designed by a team at Lawrence Livermore National Laboratory in conjunction with other universities, medical centers and so forth -- is the first instrument that automatically performs aberration measurements, makes the necessary corrections, and enables the corrected image to be viewable immediately by your eye doctor. It has tiny telescopes inside that relay light to two deformable mirrors and into the patient's eyes, focusing the light beam onto the retina. A wavefront sensor measures any optical aberrations in the incoming and outgoing light, and a MEMS-based deformable mirror corrects the distortions. The rest is basic camerawork: pass the corrected light through a confocal pinhole and into a photomuliplier tube and voila! You have a lovely high-resoltion digital video of the retina.

And that's not all. Just as telescopes help you see things that are far away, microscopes help illuminate the world of the very small. So it's probably not all that surprising that adaptive optics are proving useful in that arena as well. Philip Batson, a physicist with IBM's T.J. Watson Research Center, has incorporated AO into his electron microscope, improving resolution to such a degree that he can now routinely image the positions of single atoms. He swears that "the signal from a single atom is strong enough to get good quality images in a few tens of milliseconds, allowing the taking of sequences of images to follow atomic processes.

Electron microscopes, for the curious, use magnetic lenses to focus electrons into very small beams so scientists can peer at atomic-scale details in very thin slices of materials -- like silicon and similar compounds commonly used in the electronics industry. But just as with any other lens, there are aberrations -- most notably the dreaded spherical aberrations -- blurring the images.

Batson and his colleagues found an ingenious solution: they combined seven sets of magnetic lenses with modern computers to actively correct the aberration in real time. So their souped-up electron microscope can produce an electron beam only three billionths of an inch wide -- smaller than a single hydrogen atom. And that means they can now see objects smaller than a single hydrogen atom. This, in turn, makes it easier to spot defects in the atomic structure of semiconductor materials, such as extra or missing atoms, and figure out how to correct those defects. As Batson succinctly put it, "We can't fix what we can't see."

So there you have it: an ingenious collection of tiny waveguide sensors, actuators, computers and MEMS-based deformable mirrors can shed light not just on the mysteries of our great expansive universe, but also on the realm of the very, very small -- a Grand Unified Technology, if you will. This may be the International Year of Astronomy, but other branches of science shouldn't feel left out: ultimately, it's all connected.

Photos: (top) Images of individual retinal cells. Source: Lawrence Livermore National Laboratory. (bottom) Image of a lattice crystal using IBM's scanning electron microscope. Source: Cornell University.

Carl Sagan Honors Humason

October 22, 2008

Look what I found in my YouTube wanderings: a classic episode of Cosmos in which host Carl Sagan remembers Milton Humason, the subject of my most recent post.

So Many Galaxies, So Little Time

I've spent the last few days at the Industrial Physics Forum in Boston, Massachusetts, hearing all kinds of talks about the frontiers of imaging technologies in fields as diverse as marine science, materials physics, and astronomy and astrophysics. As is often the case when I get a peek into the near future, it compels me to also take a look back at the past -- and today's trip down memory lane takes us back to 1917, and the story of a lowly janitor at Mount Wilson Observatory (MWO) who went on to collaborate with Edwin Hubble, and helped Hubble discover that our universe was still expanding.

His name was Milton Lasell Humason, and he was born in Minnesota in 1891. His formal education ceased at age 14, when he dropped out of school, eventually becoming a "mule skinner" transporting materials and equipment up Mount Wilson while the famed observatory was under construction in 1910. The trips up and down the mountain also provided the raw building materials to construct associated housing for the working scientists. He soon married the daughter of the Observatory's engineer, which might explain how he ended up rising, in 1917, to the lofty position of, um, janitor at MWO. But the young man clearly had potential and was soon promoted to night assistant. He was interested in the work done at MWO, and enjoyed helping out with the observations.

The associated instruments included a spectrograph: an instrument that separates an incoming light wave into a frequency spectrum. This was critical because by then, scientists knew that chemical elements emitted very specific spectral signatures. So analysis of the data from the spectrograph could tell them which elements were present in the collected light, giving clues as to the chemical makeup of the objects emitting that light. The sun, for instance, showed spectra corresponding to elements like magnesium, hydrogen, iron, and so forth.

Anyway, in 1919, MWO founder George Ellery Hale elevated Humason to staff member -- quite the controversial appointment, considering Humason's pronounced lack of formal education. No doubt there were whispers of nepotism; he had married the engineer's daughter. Never mind a PhD did, he didn't even have a high school diploma. What he had were natural intelligence, a quiet manner, attention to detail, and a whole lot of patience. This made him one of MWO's most meticulous observers, discovering a comet, and only barely missing out on the discovery of Pluto. (He thought the image of Pluto on his photographic plate was a defect -- not a planet, or whatever Pluto's status happens to be this week.)

But Humason's greatest achievement was the role he played in Hubble's momentous discovery of the expanding universe. See, the spectrograph also enabled astronomers to measure the telltale spectra of distant galaxies too faint to be detected with just the optical telescope. Humason painstakingly photographed the fields containing such galacies -- a tedious task that took several nights of exposure to achieve a usable spectrum -- which he then used to help Hubble measure the velocites of 620 galaxes, based in the telltale "red shifts" in their spectral features. And that's how Hubble determined that our universe was still expanding... a revolutionary discovery that completely altered our view of the universe.

Humason rarely receives much credit for his role in Hubble's discovery, but he wasn't the sort to bear his mentor a grudge. He went on to make all kinds of contributions to astronomy, studying even more galaxies, lots of supernovae, and various faint blue stars, including white dwarfs. And in 1950, he finally got his PhD, in the form of an honorary degree. Not bad for a high school dropout.

Photos: (top) Workers transport the mirror for the 100-inch telescope up the San Gabriel Mountains to the Mount Wilson Observatory, then under construction. Source: Los Angeles Public Library, via Wikimedia Commons. Public Domain. (bottom) Milton Humason (far left) posing with Hubble, Albert Einstein and other prominent scientists during Einstein's January 29, 1931 visit to the observatory. Source: The Carnegie Institution, via Cosmic Variance.