Credit score: Lisa Crawford Bruhn
David L. Crawford, an astronomer and one of many pioneers of the trendy dark-sky motion, died peacefully July 22 in Carlsbad, California.
Throughout a decadeslong tenure at Kitt Peak Nationwide Observatory (KPNO) in Tucson, Arizona, he was famend for his work in stellar photometry and led the development of two of the best 4-meter telescopes on this planet.
However his most impactful legacy might lie not in any particular person instrument however as a frontrunner within the struggle to protect darkish skies for all. He was a founding father of the Worldwide Darkish-Sky Affiliation (IDA), now generally known as DarkSky International, and labored to teach native officers and the general public on the fragility of the night time sky and finest lighting practices to preserve it. His tireless efforts and adept coalition-building contributed to municipalities in southern Arizona adopting a few of the strongest lighting codes on this planet.
Immediately, the motion that he helped begin has gone global. IDA has licensed a whole bunch of dark-sky locations all over the world in 22 international locations, and its work has contributed to a rising consciousness of the significance of the night time sky as a useful resource and a part of humanity’s shared cultural heritage.
“I personally contemplate Dave to be one of many best environmentalists of the late twentieth and early twenty first centuries,” IDA co-founder Tim Hunter wrote in a statement launched by the group. “Dave introduced the problems of sunshine air pollution, gentle trespass, and high quality nighttime lighting to the forefront of public consciousness.”
Crawford was additionally a former chairperson of the American Astronomical Society’s committee on gentle air pollution. “In lots of respects, Dr. Crawford was the founding father of the trendy dark-sky motion, and we owe a lot to his imaginative and prescient and management,” the committee stated in statement. (The group is now generally known as the Committee for the Safety of Astronomy and the Area Atmosphere, or COMPASSE.)
From astronomer to advocate
Crawford was born in 1931 in Tarentum, Pennsylvania, and acquired his Ph.D. from the College of Chicago, serving as a analysis assistant on the affiliated Yerkes Observatory in Williams Bay, Wisconsin. After a brief stint at Vanderbilt College in Nashville, Tennessee, he took up a workers place in 1960 at Kitt Peak, the place he would spend the remainder of his analysis profession. From 1963 to 1973, he served as building venture supervisor of the Nicholas U. Mayall Telescope at KPNO and its southern counterpart, the Victor M. Blanco Telescope atop Chile’s Cerro Tololo. The Mayall and Blanco telescopes stay necessary services within the examine of darkish power, every performing state-of-the-art surveys of distant galaxies with the Darkish Vitality Spectroscopic Instrument and the Darkish Vitality Digicam, respectively.
At Kitt Peak, Crawford established himself as a frontrunner within the struggle towards gentle air pollution by founding KPNO’s Darkish Sky Workplace together with his colleague Invoice Robinson. Along with different observatories, they satisfied native officers in Arizona and Mexico to maneuver towards low-pressure sodium lighting, which emits at wavelengths that could possibly be simply filtered by skilled services. “We don’t wish to see southern Arizona go the way in which of southern California, the place we’re shedding the utmost usefulness of a number of main observatories due to unrestricted development in outside night time lighting,” Crawford instructed Astronomy within the July 1982 difficulty.
His work took on one other dimension a number of years later when he was approached by newbie astronomer Tim Hunter. In Hunter’s telling, the skies above his private observatory in Tucson had lately been stuffed with wayward gentle from the close by College Medical Middle. Because it turned out, the middle had put in the low-pressure sodium lighting beneficial by skilled astronomers like Crawford — however with out shielding, considerably decreasing the sky high quality for newbie astronomers. After a number of conferences with Crawford and Robinson, Hunter stated, “What initially started as a contentious dialogue progressively developed right into a friendship and a shared dedication to defending the night time sky.”
Crawford and Hunter based IDA in 1988. In August of that yr, Astronomy famous that the brand new group was not taking “an ‘antilight’ tactic within the battle towards gentle air pollution” — reasonably, it supposed “to advertise using ‘good gentle,’” together with fixtures with correct shielding.
“For a few years, IDA’s headquarters was his home, with containers of papers, notebooks, computer systems, lighting fixtures, slides, pamphlets, and books unfold all through his front room, dwelling workplace, and work workplace on the [KPNO] headquarters in Tucson,” stated Hunter.
Crawford was additionally a member of the Illuminating Engineering Society, the group for lighting professionals. “He wished to find out about lighting and work with professionals who designed and put in lighting,” stated Hunter. “His objective was to make pals, not enemies.”
In August 1988, Crawford organized a colloquium in Washington, D.C., hosted by the Worldwide Astronomical Union. In November of that yr, Astronomy reported:
In accordance with [Crawford], this was the primary assembly to carry collectively astronomers from all over the world with lighting engineers, attorneys, and authorities officers involved with the hazards to astronomy. Until these issues are solved, stated Crawford in his opening deal with to the colloquium, “observational astronomy will finish.”
36 years later, the assembly’s subjects appear eerily prescient. Along with ground-based gentle air pollution, astronomers expressed concern about interference from satellites — each in radio astronomy and as streaks on photographs — in addition to the rising risk of space particles to telescopes in orbit.
Crawford served as IDA’s govt director for roughly 20 years. Throughout these years, the pages of Astronomy usually featured studies on his work, in addition to notices of conferences and colloquia the place he spoke on the subject, changing untold numbers of viewers members to his trigger. (His recruits included Sky and Telescope Senior Editor Kelly Beatty, who served on IDA’s board for a few years and penned a tribute to Crawford that can be found here.)
An inspiration throughout generations
When Astronomy reported on the IDA’s founding in our August 1988 difficulty, Hunter stated, “in case you may solely persuade producers to make solely correct, shielded lights, quite a lot of the issue can be solved in a technology.” Simply eight years later, in September 1995, Astronomy reported progress on this entrance:
Due to the schooling efforts of Crawford and IDA, lighting producers are producing higher lighting fixtures and, maybe extra importantly, are making these fixtures out there to cities, cities, and counties throughout the nation. Not too long ago, Hubbell Lighting, Inc., got here out with a package to retrofit the traditional 175-watt “cobra” head fixture. It has been estimated that greater than 10 million of those lights hold from poles, homes, barns, and sheds all through the nation. For the one-time value of about $45, the sunshine could be refitted with a protect that turns the dreaded fixture right into a full-cutoff fixture and a 70-watt lamp. As a result of the sunshine is directed down, the identical quantity of sunshine nonetheless reaches the bottom, whereas the lamp’s proprietor reaps multiyear financial savings with out shedding any effectiveness.
During the last decade, the affect of such fixtures on the night time sky has taken a turn for the worse, particularly as municipalities and companies have moved swiftly to put in LEDs. The know-how brings additional power financial savings, however the overuse of unshielded, broadband LEDs has launched a brand new spherical of threats to astronomy, cultural heritage, wildlife, and human well being, as Christopher Cokinos detailed in our July 2024 issue.
Associated: How to win the fight against light pollution
On high of that, the spaceborne hazards to astronomy recognized 36 years in the past by Crawford and his colleagues have solely been amplified by megaconstellations like SpaceX’s Starlink.
These multiplying threats make the work that Crawford began much more important — and it is going to be as much as our technology to complete it. Whereas the struggle towards gentle air pollution goes on, Crawford’s legacy of forging coalitions between astronomers, environmentalists, engineers, and policymakers will stay a blueprint for a few years to come back.
