As the human mind and human senses reach ever-farther out into space, we keep encountering new things that require new objects that require new names. Some of these have ancient origins; some (like "black hole") have effectively crossed over into modern pop culture. But even those of us who, like myself, use them all the time rarely stop to think about where the terms come from.
An interacting pair of galaxies, called Arp 273. Until a century ago such objects were called nebulas (Latin for "fog" or "mist"). Credit: NASA/ESA/Hubble. Today I'm taking a step back, looking at the people and stories behind the cosmic buzzwords. For those of you who enjoy reading about the universe--or those of you who are encountering the buzzwords through the popular Cosmos television show--this is a chance to join me in a walk through the history of science. Astronomy. Let's start all the way at the beginning. Honestly, I never thought much about the meaning of "astronomy," assuming it simply means "study of the stars." Close, but no cigar. It comes from the Greek words astron and nomos, which literally mean "law of the stars" or "custom of the stars." The distinction is significant. Originally the purpose of astronomy was not to understand the construction of the universe, but to make sense of the ways that the stars affected life here on Earth. Astrology was not recognized as a separate term until the 14th century; until then, astronomy and astrology were one and the same. Planet. This is another ancient Greek word, meaning "wanderer" (planetes). The obvious reason: The planets wander through the sky, unlike the stars which remain fixed in place (at least on human timescales). Modern astronomers have developed an elaborate set of naming conventions for new asteroids, moon, and features on planets. The system, policed by the International Astronomical Union, weirdly does not have a convention for the naming of new planets. Galaxy. The name is derived from gala, ancient Greek for milk, because of the milky appearance of the Milky Way in the sky. (Milk sugar is called galactose--same reason.) Tthe first use of the term "Milky Way" came much later, in Chaucer's 14th-century story The House of Fame: "See yonder, lo, the Galaxyë Which men clepeth the Milky Wey, For hit is whyt." And the concept that the universe is full of other galaxies was not well accepted until 1929! Nova. The word just means "new" in Latin, and derives from the book De Stella Nova (The New Star), written by the pioneering astronomer Johannes Kepler, in which he described a star that suddenly appeared in 1572 (now understood not as a new star but as a dying, exploding one, called Tycho's Supernova). Supernova. In the 1930s, the wildly creative and legendarily irascible Swiss astronomer Fritz Zwicky realized that there were two very different classes of exploding stars: regular novas and others that were far brighter and more powerful. Establishing a tradition that would soon be copied by comic book writers, he called the more powerful type of explosion a "super-nova." You can read the full story of Zwicky's unusual life here. Dark matter. Zwicky is also responsible for this word, and this discovery. In his studies of the motions of galaxies he realized that some additional unseen matter must be exerting a gravitational influence on them. In a forward-thinking 1933 paper he called thismissing stuff dunkle Materie, or dark matter. We still don't know what it is. Big Bang. The now-famous name for the explosive origin of the universe was coined by someone who did not actually believe in the theory. Astronomer Fred Hoyle preferred a different, "steady state" model of the universe, in which it expanded but had no beginning or end. In a 1948 BBC radio show, Hoyle called the competing theory the "Big Bang." Many scientists took the name as an attempt at ridicule, though Hoyle insisted he was just trying to clarify the difference between the two ideas.
Stylized timeline of the universe shows how dark energy is boosting the effect of the big bang. Credit: Rhys Taylor, Cardiff University. Black hole. Who actually came up with the name? We will never know. The name is credited to physicist John Wheeler, who developed much of the theoretical understanding of these bizarre objects. At a 1967 conference in New York City he asked the audience what to call the things. Someone in the audience shouted out "black hole." Wheeler liked the idea, used it regularly thereafter, and the name stuck. The physicist Richard Feynman, one of Wheeler's former students, chided him for picking a name with "naughty" connotations. Wormhole. Another John Wheeler special. It comes from a 1957 paper in which he explored the wild possibility that physical fields could link together distant regions of space, almost like a secret tunnel between two locations in the universe. For some reason, there was no objection from Richard Feynman regarding this one. Quasar. The other terms are associated with names who are well known in the history of science. This one surprised me. American astronomer Alan Sandage first identified the compact, incredibly powerful astronomical objects we now call quasars. But the name came from the Chinese-American astronomer Hong-Yee Chiu, and the name appeared first not in an academic journal but in a semi-popular 1964 article in Physics Today. Chiu wrote: "For convenience, the abbreviated form 'quasar' will be used throughout this paper." (It is a contraction of "quasi-stellar radio source.") Dark energy. It is the newest and least familiar term on this list, but dark energy is one of the most intriguing mysteries in cosmology today. It is the blanket term for the unknown force or field that is pushing space apart, causing the expansion of the universe to speed up. Cosmologist Michael Turner coined the name "dark energy" to capture both its essential quality and its deeply unknown nature. He also sparked a lot of confusion with dark matter. When asked if the name was really his idea he responds, somewhat sheepishly, "guilty as charged." Curious about other buzzwords in astronomy and physics? Add your comments below and I'll be happy to weigh in. You can also follow me on Twitter: @coreyspowell
