Friday, August 30, 2013

Brimstone, vitriol, and strong water

If you enjoy reading about history or reading old books—histories, books about science, even novels—you've probably encountered some of the wonderful old chemical terms that were in use before our current chemical notation was developed. Here are a few of my favorites:
  • Aqua fortis and aqua regia: Two powerful acids, nitric acid and a mixture of nitric and hydrochloric acids. They translate as strong water and royal water, respectively; the latter comes from the fact that it could dissolve the royal metal, gold. Don't mess with these "waters"! 
  • Vitriol: Another acid, sulfuric acid. The fact that this word is now used metaphorically to describe harsh criticism is perhaps a clue to how very corrosive such criticism can be. The word derives from an alternative form of the Latin vitreolum, the neuter form of the adjective vitreolus, or glassy, presumably because sulfuric acid is a viscous liquid that is colorless or pale yellow.
  • Brimstone: Plain old sulfur. Looks kind of funny without "fire and" in front of it, doesn't it? The sulfurous smell of gases venting from volcanoes may have inspired the use of this word to describe the torments of hell. The word comes from the Old English brynst├ín, or literally burnstone.
  • Plumbago: Graphite, one of the well-known forms of carbon. The word comes from the Latin word plumbum, for lead, because graphite resembles certain lead ores. Plumbago is also the name of a type of plant, aka leadwort. This name also derives from plumbum, perhaps because the roots of the plant turn the hands gray when they are handled, or because of a mistaken belief that it was efficacious against lead poisoning. 
 
Plumbago auriculata, aka blue plumbago or Cape plumbago. It will not do squat for lead poisoning, but it's a perfectly nice flowering shrub nonetheless. ©Stephanie Watson Photography under a Creative Commons Attribution-ShareAlike license.
  •  Sal volatile and salt of hartshorn: Ammonium carbonate, which was used as a smelling salt. I first encountered sal volatile in some old novel (probably in the context of a young lady withdrawing a vial of it from her reticule to aid a companion who was overcome by faintness, perhaps when she saw the gentlemen she esteemed dancing heartlessly with another). I had no idea what it was or how on earth it worked. All was made clear when I learned that it was the pungent odor of ammonia that brought young ladies back from their swoons. Aqueous ammonia was known as spirit of hartshorn because it was distilled from the horns and hooves of male red deer, or harts.
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Wednesday, August 28, 2013

Naming the heavens

The International Astronomical Union announced recently that public input will be considered when names are assigned to "planetary satellites, newly discovered planets, and their host stars." These public names will be distinct from the scientific designations, which I gather will follow the rules they always have. This seems as good a time as any to look briefly into the pleasures of astronomical nomenclature.

It seems to me that astronomical objects have a particularly rich naming tradition, but that may be just because my background is in astronomy. Stars and other objects may have more than one name, and even more than one official name. Consider the star Vega. It's part of the summer triangle, a group of three stars that form a huge triangle that's visible from early summer until well into the autumn.

It's also called ╬▒ Lyrae, which indicates that it's the brighest star in the constellation Lyra. This name follows the system Johann Bayer set up early in the 17th century, in which the stars in a constellation are designated by Greek letters, from the brightest to the dimmest. Once people started taking a good look with telescopes, of course, they found far more stars than the Greek alphabet could cover, so other systems came into use, for example, Flamsteed numbers, from a catalog published by John Flamsteed in 1725. In this system, Vega is 3 Lyrae.

So we have three names for Vega so far. When I was an undergrad taking an observational astronomy class, one of our early exercises was to observe various astronomical objects identified by sometimes cryptic designators; the point was to familiarize us with the catalogs and other tools used by astronomers, as well as with the telescope. One of the objects was HD 172167, which turned out, when the proper source was consulted, to be none other than our old friend Vega. In fact, this familiar star actually has 55 different monikers, most of them numbers in catalogs.

You will perceive a certain creeping abstraction here. Vega is an interesting name with a history of its own (which we will probably go into another time). Lyra is a constellation with a tragic myth behind it. And in this they resemble many astronomical objects, which are rich in legend and lore. Dubhe and Merak, the Guardians of the Pole; Algol (the ghoul); Antares, the rival of Mars; the Beehive Cluster; the Seven Sisters: They might almost be the titles of fairy tales or science fiction stories. But HD 172167? SAO 67174? HIP91262? Where did the romance go?

Actually, these seemingly opaque designators have a wealth of history and lore behind them too. An HD number, for example, indicates a listing in the Henry Draper catalog. Draper was a doctor and an accomplished amateur astronomer who clearly saw the potential of one of the new technologies of the time, photography. He made the first photograph of the spectrum of a star (Vega, no doubt chosen because it's so bright). He was also the first to photograph a nebula (the Orion Nebula). His wife, born Anna Mary Palmer, assisted him with his astronomical work, and when he died, in 1882 at the age of 45, she established a memorial in his name to fund further astronomical research based on photography and spectroscopy.

Henry Draper, nineteenth-century doctor and astronomer extraordinaire. His name lives on in the Henry Draper Catalog and its two extensions. I wish I could have found a photo of his wife as well, but I couldn't.
The memorial funded a gigantic project at Harvard College Observatory: classifying stars according to their spectra. Edward Pickering led the project, and Annie Jump Cannon performed the astonishing task of looking at well over a quarter of a million stellar spectra and assigning each star to its proper type. The system of stellar types that we now know, in which stars are classed as O, B, A, F, G, K, or M according to their temperature, from the hottest to the coolest, was still being developed, and Cannon helped resolve a disagreement between two competing systems. Overall, her work was a massive achievement.

Annie Jump Cannon, star classifier extraordinaire. Her patient and painstaking work over decades established a research tool that is still in use today.

Stars are, of course, only one kind of heavenly body. There are various types of nebulae, star clusters, and galaxies, each with a naming system and various catalogs tabulating the cosmic inventory. I hope to get into more of this in future posts. For now it is enough to say that the story is the same for them as it is for the stars: they have the equivalent of common names, like the Orion Nebula, and various official designations. And for each drily abstract catalog number, from the more or less familiar Messier numbers that identify 100+ faint fuzzy objects, to the New General Catalog (NGC), which lists a much larger group of non-stellar objects, to the most specialized catalogs of heavenly bodies—each of these things represents years of careful human labor, many dollars, and many observations. Many human stories. I'm glad that the human touch is being added to the naming of extrasolar planets. But I also love the names we have now, which are often monuments to human dedication and imagination.

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Monday, August 26, 2013

Wolf feet and golden leeks

Sometimes it's fun just to see what you can figure out about something by knowing the Latin or Greek roots of its name. This is also a great way to spot connections between very different things. I was delighted, for example, to find out that the name of the rhododendron has a charming etymology. The rhodo part comes from a Greek word meaning rose or rosy. You can see this root in the name rhodopsin, the pigment in the eye that is sensitive to red light. (You may also have heard it called visual purple.) There's also a beautiful pinkish stone called rhodochrosite. The dendron part is from a Greek root meaning tree. Thus we also have dendrite, a branch extending from a nerve cell in the brain. Put it together, and you have rosy tree, a pleasing name for this flowering shrub.

Rhodochrosite specimen at La Plata Museum in Argentina. This lovely mineral shares a Greek root with visual purple (rhodopsin) and the rhododendron. ©Leandro Kibisz under a Creative Commons Attribution-ShareAlike license.

Or consider the chrysanthemum. The chrys part is from a Greek root chrysos, meaning golden, and anthemum comes from the Greek anthemon, which means flower: golden flower. Chrysos also contributed to the names of the minerals chrysolite (golden stone) and chrysoprase (which translates literally as golden leek). Chrysoprase is a greenish mineral, but the word was formerly used to refer to a yellowish-green gemstone. We also see chrysos in chrysalis, the golden case surrounding a pupa.

Years ago, I was hiking with my younger son when we spotted a Lycopodium, or club moss. I thought I recognized some roots in the name Lycopodium, so I spelled it out for myself. I guessed that the lyco part is related to the Greek word for wolf, and the pod part is related to the Greek word for foot. "Wolf foot?" I said to Patrick, puzzled. It turns out that the names club moss and Lycopodium both come from the way this plant resembles other things: a club or a wolf's paw, respectively. The genus Lycopodium has been split up, and the species pictured below, Lycopodium digitatum, has since been reclassified as Diphasiastrum digitatum.1

Several other plant names feature the lyco root, including a genus of grasses called Lycurus (the common name is wolfstail) and a genus of plants called Lycopus (a variant on wolf foot; cf. octopus, named for its eight feet). It also appears in lycanthropy, which refers to the wolf-man of folklore. The pod root also appears in arthropod; arthropods, that is, crustaceans and insects, have jointed appendages. At the risk of taking this thing too far, I will point out that you also see arth in arthritis, an inflammation of the joints, and arthroscopic surgery, which can be performed on any joint but is often done on the knee.

Photograph of Lycopodium digitatum
Diphasiastrum digitatum, formerly known as Lycopodium digitatum. You can sort of see clubs (wee clubs, useful perhaps to belligerent spiders) or long-fingered paws (that's digitatum as in digits, or fingers). ©Patrick Alexander under a Creative Commons Attribution-NonCommercial-NoDerivs license.
This game could go on indefinitely. There's pachysandra, which has thick (pachy, from a Greek word) stamens (the male part of the flower, from the Latin root androus, meaning male). Maybe your mind has already jumped to the elephant, or pachyderm, with its thick skin. The horsetail fern is also called Equisetum, from the words for horse and bristle. I will leave it there for now, but we will be coming back to this sort of thing many times in the future.


1 I owe Patrick a debt of gratitude not only for introducing me to Lycopodium but for keeping me up to date on its current classification and suggesting several other wolf-related plant names.

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Friday, August 23, 2013

Oology and other ologies

When I think of the sciences, I first think of biology, physics, chemistry...the names of subjects you can take a high school class in. Here are some finer-grained specialties within those sciences.

  • Tribology: This term was coined relatively recently to describe the science of surfaces in contact (friction, lubrication, and wear). It comes from the Greek verb meaning to rub. Whether you were aware of it or not, you've almost certainly experienced the triboelectric effect, in which a material gains electrical charge by being rubbed against another material (for example, when you shock yourself on a doorknob after shuffling across a carpet).
  • Oology: This subfield of zoology deals with birds' nests and eggs. The first two letters are pronounced as two syllables (oh-ah, roughly), and the word comes from the Greek root oion, meaning egg. The same root is ultimately the source of oolite, a type of calcium-carbonate-based rock composed of small spherical grains (which are also called oolites, or ooliths: egg stones).
  • Somnology/hypnology and oneirology: Most of the roots I'm talking about here are Greek, but in the scientific term for the study of sleep, we have a choice of Latin and Greek roots. Somnus was the Roman version of the Greek god of sleep, Hypnos. Hypnology is also used to describe the science of hypnosis, and somnology seems to be more common among scientists. Interestingly, several phenomena related to sleep retain the hypno- root: hypnopompic and hypnagogic hallucinations. These harmless but sometimes terrifying events occur as you're waking up or falling asleep, respectively. Oneirology is the scientific study of dreams; this one is from the Greek root oneiros, or dream.
  • Pedology and edaphology: These two divisions of soil science come from the Greek roots pedon (soil or ground) and edaphos (ground or basis). Pedology considers the soil itself, and edaphology considers the soil as the home of living things. Pedon is ultimately derived from the word for foot, the soil being underfoot.
Happy weekend! See if you can work any of these into your conversations this weekend.

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    Wednesday, August 21, 2013

    Sunflowers, moonflowers, and asters

    While we're talking botany and astronomy, let's look at the connections between plant names and the sun, moon, and stars. First, and most obvious, we have the sunflower, so called for its resemblance to the sun. (The genus name Helianthus is very straightforward; it's essentially sunflower in Greek.)

    Heliotrope is named for its behavior: it turns toward the sun (helios in Greek) as it crosses the sky. The trope part of the name comes from the Greek root tropos, meaning turn. A tropism is an instinctive response to some stimulus, often a turning toward or away from something. Heliotrope has also gone by the name turnsole, which is related to the Latin word for the sun, sol. Because some types of daisy open and close with the rising and setting of the sun, its name comes from the Old English for day's eye.

    Daisy, or day's eye; some types open in the sunshine and close in the dark.

    Tropism, by the way, is one of those fun words that you can make new words from by adding an appropriate prefix. Scientists talk about thermotropism (attraction to heat) and phototropism (attraction to light). I talk jokingly about bibliotropism, my own tendency to drift toward the books in any room.

    I also learned recently that the word tropic comes from the same Greek root, tropos. I'm reading the sixth book in Colleen McCullough's Masters of Rome series (highly recommended, by the way), and I got to the part where Caesar and Cleopatra were traveling up the Nile together. They were having a well-informed discussion of the natural history of the region, as political leaders are apt to do when on a junket (aren't they?). Caesar mentioned that Eratosthenes had given the Tropic of Cancer its name because it marked the point where the sun reached its northernmost position, on the summer solstice, before it turned around and headed south again in its annual cycle. (Of course the sun doesn't really turn around, but that's how it looks.)1

    The moon and stars are also well-represented among the flowers. The moonflowers are a confusing tribe, including various unrelated plants that bloom at night. For example, the genus Hylocereus is a type of cactus that produces big gorgeous flowers, often only one flower on one night a year. It's also called the night-blooming cereus (although other things are also called that). If you've heard of someone waiting eagerly for a night-blooming cereus to finally blossom, it was probably a Hylocereus undatus.

    Another moonflower, the genus Datura, produces lovely nocturnal blooms and potentially lethal alkaloids; it's also known as the angel's trumpet for its trumpet-shaped flowers. Datura is a member of the Solanaceae family, AKA the nightshades. We'll be meeting this large and varied family again; it contains a wide range of plants, from the potatoes and tomatoes and eggplant on the table to the petunias in the garden and the tobacco, datura, and deadly nightshade that entice and kill. Interestingly, the name Solanaceae might also come from the Latin sol (I've seen several possible reasons for this). There are other explanations, but if it's true, it's curious that a family named for the sun should also be called nightshades.

    The Mentzelia are another type of moonflower, although they're also called evening stars or, most commonly, blazing stars, because they not only bloom at night but have a star-like shape. They're also called stickleaf; the leaves contain many small barbs that enable them to stick to fur, socks, pants, etc., although it's not clear what use this might be to the plant.

    With the Mentzelia, we can turn again to flowers that are named not for when they bloom but for their appearance. There is an entire family named for its star-shaped flowers, the Asteraceae. The Mentzelia are not members of it; however, the Asteraceae do include another blazing star, liatris. Along with the asters, those starry flowers of late summer and fall, the family also includes dandelions, artemisia, zinnias, marigolds, and black-eyed Susans. They also take us back to where we started, because sunflowers and most daisies are members of the Asteraceae family.

    Thus ends our whirlwind tour of heavenly bodies on Earth. If you have a favorite that I haven't covered, please post it in the comments.


    1 The Tropic of Cancer, at about 23.5° N, is the northernmost latitude at which you can see the sun directly overhead when it's at the zenith (roughly noon); it happens only once a year, on the northern summer solstice. When the Tropic of Cancer was named, the sun was entering the constellation of Cancer on the northern summer solstice; because of precession (the slow wobble in Earth's rotational axis), the sun is now in Taurus on that date.

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    Monday, August 19, 2013

    Suns, moons, galaxies ... earths?

    One of the things I had to decide when I started this blog was how I was going to treat the word earth. Should I use earth or Earth? Do I need to use the word the? It may seem that I'm taking the geek part of the title Science Word Geek far too seriously here, but if you'll bear with me, I think I can explain how the most minute of minutiae can sometimes point to a shift in worldview.

    Earth is the proper name of our planet. So of course you would simply say Earth, the way you say Jupiter or Saturn. But wait a minute, we don't usually say just Moon or Sun: "the astronauts landed on Moon"? Nah, it should be the moon. In a nonscientific context, earth alone, lowercase, makes sense, for example, in the phrase down to earth. But there are lots of times where I might feel more comfortable using Earth, say to compare the topography of Earth and Mars. I think that will probably be the most common case on this blog, so I decided to use Earth.

    That's Earth! Image is one of 60 frames taken by Voyager 1 in February 1990 and shows Earth from about 4 billion miles away--Carl Sagan's Pale Blue Dot. Image courtesy NASA/JPL-Caltech.

    I think the reason that the moon seems so natural and the earth doesn't always seem quite right may be that I grew up knowing there were multiple moons in the solar system, so to me they seem inherently generic. Our moon is obviously one of many, and to me, it always has been. I think there's no reason to believe we won't someday find Earthlike planets around other stars, but until we do, Earth is singular and unique in a way the moon and sun are not. We have discovered super-Earths, but not earths. We've also found Jupiter-like and Neptune-like planets around other stars, but I think most people still capitalize Jupiter and Neptune in those cases. We even have subtypes: hot Jupiters, eccentric Jupiters (their orbits, not their personalities), and hot Neptunes, but I've seen hot jupiter rarely if at all (and I just now had to argue with autocorrect in order to use a lowercase j).

    It seems to me we're going through an interesting transition in how we view our universe, and we've been through this kind of shift before. For example, Oceanus was the name of the ocean believed to encircle the known world in ancient times, when a great deal less of the world was known. Now we don't even think twice about the fact that there are multiple oceans on Earth, and we speak casually of methane oceans on Titan or a subsurface ocean on Europa.

    Something similar had to have happened with the sun as we recognized that it was one star among many, and with the moon as we learned that other planets had moons, starting with Galileo's telescopic observations of the four largest moons of Jupiter. More recently, in the twentieth century Edwin Hubble resolved a lively debate about whether spiral nebulae were part of the Milky Way or were "island universes," or as we would put it now, separate galaxies in their own right.

    Hubble used images taken by the Hooker 100-inch telescope, which was able to resolve individual stars in the Andromeda Nebula, and applied a newly discovered relationship between the period of a certain type of variable star (how long it took to go from bright to dim and back again) and its intrinsic brightness. If you know the inherent brightness of a star and its brightness as viewed from Earth, you can calculate its distance. Hubble found that the Andromeda Nebula was in fact the Andromeda Galaxy, around 2,000,000 light years away and far too distant to be part of the Milky Way. So the singular term Galaxy, which came from a Greek root meaning milk, became lowercase when it expanded to cover all of the other galaxies. Scientific papers still distinguish between Galaxy (our own) and galaxy (one of the others).

    I'm delighted to be living in a time when we can see the same shift happening with regard to planets. There are enough known exoplanets that we can begin to classify them according to type of planet and even type of solar system. My iPad chirps at me every time a new exoplanet is added to the database—what a heady experience! It's well worth the occasional editorial perplexity.

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    Friday, August 16, 2013

    Two Scotsmen and a tree

    The story of Scottish botanists Archibald Menzies, David Douglas, and the tree that bears both their names is a good example of the challenges of establishing either a binomial name or a common name for newly observed species. (Incidentally, the name Menzies is pronounced "MING-iss.")

    The tree is the Douglas fir, common in the forests of western North America, particularly in the Pacific Northwest. I learned recently that some people prefer the name Douglas-fir, with a hyphen, because it's not a true fir. This is only the beginning of the complexities of this tree's name. Today it's one of the most economically important timber trees worldwide and is popular as a Christmas tree, but for many years it was quite a puzzle to botanists.

    The name Douglas-fir honors David Douglas, who botanized in the New World during his brief but adventurous life in the early 19th century. Born in Scone, Scotland, he received training in botany in Scotland and made three plant-collecting expeditions for the Royal Horticultural Society of London. During his second and most successful trip (1823–1827), which took him to the Pacific Northwest, he introduced about 240 plant species to the British Isles, both garden plants and various timber trees. In 1827, he sent seeds from the Douglas-fir back home, estimating that this tree would do well there. Indeed, a tree grown from one of his seeds still graces the grounds of Scone Palace.

    Douglas fir on the grounds of Scone Palace in Scotland, which was grown from a seed sent home by Douglas in 1827. ©Aaron Bradley under a Creative Commons Attribution-ShareAlike license.
    The journal of Douglas's second North American trip tells of his travels and work under often difficult conditions, albeit in spectacularly beautiful places. On his third trip, Douglas returned to the Pacific Northwest and also visited Hawaii. It was there that he met his tragic and peculiar death at the age of 35. He died on Mauna Loa after he accidentally fell into a pit trap and was trampled by a wild bull. His name lives on (as douglasii) in the scientific names of more than 80 species of plants and animals.

    Douglas was one of the first Europeans to climb Mauna Loa. The very first Europeans included Archibald Menzies, who climbed it with two other people in 1794 when he was serving as naturalist on the Vancouver Expedition of 1791–1795. Menzies was a doctor and botanist whose name also appears in the names of various New World plants that he observed and collected, including the scientific name of the Douglas-fir.

    He visited the Pacific Northwest, where he collected specimens of the Douglas-fir and sent them back to England, but for some reason the tree evidently did not enter cultivation there at that time. Lewis and Clark also observed the tree and contributed drawings (and possibly specimens, although if so they are now lost) to fuel the discussion of how to categorize it and come up with a suitable scientific name. 

    This turned out to be a long and complicated business because of confusing resemblances to more familiar trees. Various genera were suggested: Pinus (pine), Tsuga (hemlock), Picea (spruce), and Abies (fir). The genus Pseudotsuga (false hemlock) was introduced in 1867, but the official name of Pseudotsuga menziesii was not formally accepted until the 1950s.

    It's quite a story, and I only hit the high points. This is an excellent example of how the elegance of binomial nomenclature often represents the distillation of many observations of an organism over a long and fascinating history. If you enjoy reading about scientific explorers, check out the writings of Douglas and Menzies listed below.

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    Wednesday, August 14, 2013

    Binomial nomenclature (and Lady Gaga's ferns)

    As I mentioned in an earlier post, common names, although rich in lore, are not always all that helpful for uniquely identifying an organism. They also don't reflect the evolutionary history of organisms or the relationships among them. That's why scientists eventually devised a system they could use to communicate unambiguously.

    After the concept of species was introduced by John Ray in 1686, natural scientists experimented with conventions for naming species. In 1735, Carl von Linne (aka Carolus Linnaeus), a Swedish botanist, introduced his system of binomial nomenclature for plants and animals. Binomal indicates that each organism has two names; one is the name of its genus, which it shares with other organisms in the genus, and the other is its trivial name, also called the specific name or specific epithet, which is unique to the species. The system is governed by two international bodies, one for animals and one for plants.

    Latin grammar is applied to binomial names; for example, menziesii translates as "of Menzies" and is used for several species to honor Scottish botanist Archibald Menzies (about whom we will hear more soon). As this example shows, the specific name doesn't have to describe the organism; it can name a person (typically but not always a discoverer), a location, or a real or imagined resemblance.

    Although the names are formulated according to the rules of Latin grammar, they can originate in other languages. In at least one instance, Greek and Latin roots are both used in the same name: the swordfish, Xiphias gladius. Xiphias comes from the same Greek root (sword) as xiphoid, which describes the blade-shaped xiphoid process in the human body, and gladius is from the Latin word for sword. The name seems to be saying: "Did I mention that this fish has a sword?" Incidentally, you also see gladius in the word gladiator, for obvious reasons, and perhaps more surprisingly in gladiolus, because of the swordlike leaves. (So now you know what the gladiator and the gladiolus have in common.)

    Bouteloua curtipendula, or side-oats grama, the state grass of Texas. The genus is named for two Spanish botanists, Claudio and Esteban Boutelou. Curtipendula can be translated very roughly as "short danglies," in reference to the way the seeds hang from the side of the stalk. ©Matt Lavin under a Creative Commons Attribution-ShareAlike license.

    Last year, researchers at Duke named a genus of ferns for Lady Gaga, on the basis of various resemblances and the presence of the DNA sequence GAGA. This illustrates, among other things, the role that DNA studies play today in determining the boundaries of genera and species. The new genus contains 19 species of ferns, 17 of which were previously assigned to the genus Cheilanthes on the basis of their physical appearance. The reclassification to the genus Gaga, in contrast, is based on an analysis of their DNA. The names of the two new species, Gaga germanotta and G. monstraparva, commemorate Lady Gaga's family name and her name for her fans (little monsters), respectively.

    Note that once you've named the genus, you can abbreviate it (G. monstraparva). If you're talking about an unknown species within a genus, say the genus of sunflowers, you can use, Helianthus sp., and for several species within a genus, you can say, for example, Gaga spp. Binomial names can be followed by the name of the person who first published the name (an authority) and perhaps the date of the original publication. It can also be further qualified by the name of a variety (a variant found in nature) or a cultivar (a variant developed by humans). For example, the Carnegie cultivar of the garden hyacinth is called Hyacinthus orientalis L. "Carnegie" (where the L. indicates that Linnaeus is the authority).

    As I hope the examples above show, binomial nomenclature is simultaneously an elegant and precise system and a rich repository of historical information. We'll be exploring lots of these names in this blog.

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    Monday, August 12, 2013

    Who put the meteors in meteorology?

    While we're on the subject of meteors, what have meteors got to do with meteorology? It turns out that the link between meteors and meteorology is a Greek word, meteoron, that refers to things in the air, or sky—what today we would call atmospheric phenomena. Clouds, lightning, rain, storms, wind: these are all features of the sublunary sphere (below the moon), where things were changeable and imperfect, in contrast to the unchanging perfection beyond it. Meteors were also thought to be purely atmospheric.

    Meteors are in fact an atmospheric phenomenon, but, contrary to Greek cosmology, they originate much further out. However, it didn't make sense at the time that something so fleeting could come from the supposedly perfect and unchanging realms beyond the sublunary sphere. The name meteorology for the study of the other atmospheric phenomena stuck, however. Meteorologists do talk about hydrometeors, but they have nothing to do with the interplanetary kind of meteor; they're water droplets or other types of precipitation that form in the atmosphere by condensation.

    The astronomy–astrology link is also interesting. When I was an undergrad studying astronomy, I was startled and mildly annoyed at how many people got the two confused. Sometimes it was just a slip of the tongue; the words are quite similar. Sometimes the confusion was deeper. One time, for example when I was reading a copy of Astronomy magazine, a co-worker with asked me, in all seriousness, "Do you really believe that stuff?" After various similar discussions, I became somewhat sensitive on this point.

    However, at one time astrology was astronomy, the study of the heavens. There were essentially two types of astrology: natural and judicial. Natural astrology concerned itself with figuring out the tides and the seasons and similar natural phenomena that result from the Earth's interaction with other bodies in the solar system. Eventually these pursuits segued into what we now call astronomy. Judicial astrology involved more speculative investigations of how celestial events affected humans directly, e.g., linking their personality to the positions of the planets when they were born, or the course of a disease to the influence of the moon or planets. The word judicial refers to the fact that astrologers made judgments about what they thought was going on, which differed from the more numerical and observational nature of natural astrology.

    Artist's conception of the Kepler spacecraft. Johannes Kepler, the astronomer for whom this mission is named, also cast horoscopes. Image courtesy of NASA/Ames/JPL-Caltech.

    Today we have better explanations for personalities and diseases, and astrology is recognized as unfounded nonsense. However, it was only within the last few hundred years that the astronomy–astrology boundary that we know today became firm. Kepler, who figured out that the planets have elliptical orbits and formulated three laws describing planetary motion, also earned money by casting horoscopes. Interestingly, he has both a scientific satellite and a school of astrology named after him: the Kepler mission to search for extrasolar planets, and Kepler College, which offers online training in astrology.

    More recently, astrophysics became recognized as separate from astronomy. Before the dazzling revolution in astronomy brought about by the introduction of photography and spectroscopy, astronomers could study the positions and motions of heavenly bodies but not their compositions or other characteristics, which severely limited how much they could figure out about their evolution. With spectroscopy, astronomers could determine a star's composition and temperature, how fast it was rotating, and other features—stellar spectra reveal an astonishing amount of information!—and also begin to categorize stars and figure out how they formed and aged. Thus was born astrophysics, which focuses on the chemical and physical properties of stars, galaxies, and other objects. So there you have it: astrology to astronomy plus astrophysics by a series of interesting transitions.

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    Friday, August 9, 2013

    The meteor family of words

    Sometimes words that describe the natural world come in a rather confusing clump. I'm hoping to explore many of these groups of words describing interrelated or similar concepts. Because one of the best-known meteor showers, the Perseids, is peaking this weekend, let's start with the meteor family of words.

    A meteor, of course, is that thin needle of light streaking through the night sky that we also know as a shooting star. Meteor showers occur when Earth passes through the swath of debris left by a comet. We've identified the comets that have spawned various meteor showers; the Perseids are the leftovers of Comet Swift-Tuttle. The showers themselves, by the way, are named for the constellation from which they appear to come, in this case Perseus.

    Several other words are also used to describe interplanetary dust and fragments more precisely.
    • A meteoroid is a bit of debris that would become a meteor if it entered Earth's atmosphere. They're much smaller than asteroids and range from tiny dust grains to pieces about one meter across—essentially the dust bunnies of the solar system on up to things the size of maybe a washing machine. Think of asteroids and planetoids and remember that all three are out in space.
    • A meteorite is a meteor that survives its journey through the atmosphere. Most meteors are so small that they simply vaporize in the atmosphere, but the larger ones can make it down to the surface. Both meteorites and meteors add their mass to Earth's; it's hard to tell exactly how much mass this amounts to, but estimates range from 37,000 to 78,000 tons per year, most of it from tiny bits of dust.1
    • A particularly big, bright meteor is sometimes called a fireball. The best-known recent example of this is the spectacular fireball that streaked across the sky near Chelyabinsk, Russia in February 2013. A large meteor that explodes in the atmosphere is called a bolide, from a Greek word meaning missile. The Chelyabinsk meteor broke up in the atmosphere and was so large that it's also called a super-bolide.
    • Sporadic meteors are random bits of space debris that are not associated with a particular comet. They might be fragments of asteroids that broke up, or bits of the moon or Mars that were ejected during an impact. Some of the latter even make it down to the surface sometimes; enough of these have been identified as coming from Mars that they are classified into different types.
    The next time you're out under a dark sky and see a fleeting thread of light appear in the starry sky, remember that you're watching the end of a long space odyssey, signaled by the tiny quiet flash of vaporization as a bit of space dust becomes part of Earth.


    1 Cornell Ask an Astronomer page

    Learn more:

    • The American Meteor Society has an informative site with the latest news on meteor showers and fireball sightings.
    • We're lucky this year that the Perseids occur when the moon is a waxing crescent, so moonlight shouldn't be a problem. See the AMS's Perseid 2013 page for more information about viewing the shower.
    • If your skies are cloudy, you can listen to signals from the USAF Space Surveillance Radar on Space Weather Radio; you can hear a ping every time a Perseid flies over the radar.
    • Dr. Tony Irving of the University of Washington maintains a Martian meteorites page.

    Wednesday, August 7, 2013

    Who names things?

    Most of the time, names arise mysteriously out of the collective creativity of language. Common names for plants and animals are a very rich source of information about them and their history of interaction with humans. One inspiration for this blog was a desire to learn where names like wormwood, sassafras, and lungwort came from. However, they have their limits. Is your moonflower or ironwood the same as mine? Maybe, maybe not. And consider things like Spanish moss, which is neither native to Spain nor a moss.

    When scientists communicate with each other, they require clarity and a shared understanding of the names and categories of the things they talk about. Various professional societies for scientists have naming commissions or other bodies that agree on nomenclature in that field. For example, it was the International Astronomical Union that decided that Pluto is a dwarf planet. Although this demotion caused consternation in some circles, it wasn't anything personal. It just reflects the current understanding of the contents of the solar system better. The idea is essentially to use the same name only for objects that not only resemble each other superficially, but that share deeper similarities and perhaps an evolutionary history.

    The ultimate example of precision naming may be the binomial nomenclature used to give consistent names to plants and animals. Each name indicates the organism's genus and species. The species name often reflects something about the organism (a word describing its appearance, say, or the name of the person who identified it as a species). Virginia creeper, for example, goes by Parthenocissus quinquefolia; it belongs to the genus Parthenocissus, and quinquefolia refers to the fact that the leaves appear in groups of five. In this blog, we'll learn about how the genus names were established and also about some of the scientists and explorers whose names live on in scientific names.

    Virginia creeper, also called five-finger, with its groups of five leaves (quinquefolia). I assume Virginia is the first place that Europeans saw this plant. Its range is actually much wider than the name indicates. They don't call it a creeper for nothing, though. Here's some creeping through a flowerbed.

    As we learn more about the evolutionary history of an animal or a plant, the scientific name may change. Again, the goal is to group objects that truly are related in a meaningful way. I was surprised to learn that Virginia creeper is not Hedera quinquefolia, the first name I learned it by many years ago. That's an older name that is synonymous with Parthenocissus quinquefolia (that is, it refers to the same thing) but is not used any more in scientific publications or databases. (The genus Hedera contains the ivies, and although Virginia creeper resembles an ivy in behavior, it turns out not to be particularly closely related to them.) You can see that scientific names are not quite as cut and dried as they may seem, but the goal is a clear unambiguous naming convention that reflects our best understanding of the natural world.

    Even scientific names have some scope for whimsy, however. Asteroids and genes, which are generally named by their discoverers, are two good examples. Asteroids have been named for people from Pythagoras to Lennon and McCartney. There are asteroids named Paris, Potsdam, Cincinnati, Tahiti, and even Peruindiana (after a small town in Indiana, which by the way is generally pronounced PEE-roo). Some are named for fictional characters: Mr. Spock, James Bond, and Desdemona, for instance. There's also one called Racquetball, and one called Vinifera (named by a wine lover, I assume). And speaking of wine, the zebrafish has a group of genes named for wines and a gene called moonshine that have to do with blood cell development and blood circulation, respectively.

    So maybe it's more accurate to say that all names arise out of the collective creativity of language, and that science tries to use names more precisely than we often do.

    For more information, see:

    Monday, August 5, 2013

    Why do they call it that?

    I edit scientific papers; although my background is in astronomy, geology papers may be my favorite. I love the lingo of geology—greywacke, gneiss, drumlin, plagioclase feldspar, obsidian, alluvial fan—and I’ve always been curious about the origins of some of the more exotic terms. When I started to investigate them, I found that even common terms like granite have an interesting etymology. Granite, for example, springs from the same root (so to speak) as corn—not necessarily the corn that we call corn today, but in the older sense of the word, the local grain crop. Granite has a granular texture, and the Latin word granum is the ultimate source of the words granite (from the past tense of the verb grano, "to make grainy") and corn. All right, I thought, these geology words are well worth pursuing.
    This photograph of granite used in the facade of a building at Cambridge illustrates its granular texture very nicely. © James Bowe under a Creative Commons Attribution license.

    Then I was having lunch with my son a few days later and he told me that his then six-month-old son, a born kicker, had recently kicked him in the xiphoid process (a small bone spur in the chest). I sympathized, but at the same time, the phrase “kicked in the xiphoid process” made me giggle. (It could be hazardous if an adult were to kick you there; however, a xiphoid kick from a baby is an uncomfortable indignity but not likely to be lethal.) And again I wondered, why do they call it the xiphoid process? How about the sigmoid process? What is a process, anyway?

    One last story: I was sitting near some people at a coffeehouse and inadvertently overhearing their discussion; for some reason they needed to know whether a centrifugal force went inward or outward. One of them reasoned that because of the way a centrifuge works, it must go outward, which was an excellent way to approach the question. Another nice approach is to remember that the Latin root fugere means “to flee” (a mnemonic is the phrase “Tempus fugit,” which translates literally as “Time flees”), so under a centrifugal force, objects flee the center of a circle. We can also trace fugitive and refuge back to fugere.

    Put all this together, and it occurred to me that learning more about the Latin, Greek, or other roots of scientific words and/or the stories of their origins is an excellent way to understand more about science and its history. Hence, this blog. I’m going to explore the answers to my questions about rocks, minerals, and processes, along with many other things, and share what I learn here. I hope this will be a helpful and entertaining site to anyone who is curious about science and wants to learn the stories behind the curious and often beautiful words it uses, as well as the history hidden behind very familiar words.