Knut Lundmark, Meteors and an Early Swedish Crowdsourcing Experiment

Summary

Mid twentieth century meteor astronomy demanded the long-term compilation of observations made by numerous individuals over an extensive geographical area. Such a massive undertaking obviously required the participation of more than just professional astronomers, who often sought to expand their ranks through the use of amateurs that had a basic grasp of astronomy as well as the night sky, and were thus capable of generating first-rate astronomical reports.

When, in the 1920s, renowned Swedish astronomer Knut Lundmark turned his attention to meteor astronomy, he was unable to rely even upon this solution. In contrast to many other countries at the time, Sweden lacked an organized amateur astronomy and thus contained only a handful of competent amateurs. Given this situation, Lundmark had to develop ways of engaging the general public in assisting his efforts. To his advantage, he was already a well-established public figure who had published numerous popular science articles and held talks from time to time on the radio. During the 1930s, this prominence greatly facilitated his launching of a crowdsourcing initiative for the gathering of meteor observations.

This paper consists of a detailed discussion concerning the means by which Lundmark's initiative disseminated astronomical knowledge to the general public and encouraged a response that might directly contribute to the advancement of science. More precisely, the article explores the manner in which he approached the Swedish public, the degree to which that public responded and the extent to which his efforts were successful. The primary aim of this exercise is to show that the apparently recent Internet phenomenon of ‘crowdsourcing’, especially as it relates to scientific research, actually has a pre-Internet history that is worth studying. Apart from the fact that this history is interesting in its own right, knowing it can provide us with a fresh vantage point from which to better comprehend and appreciate the success of present-day crowdsourcing projects.

Acknowledgements

This article is the outcome of a pilot study conducted in preparation for a larger research project on the history of Swedish amateur astronomy (in collaboration with Gustav Holmberg, Lund University). The pilot study was financed by a grant from the University of Gothenburg's Learning and Media Technology Studio (LETStudio). The larger project later received funding from the Bank of Sweden's Tercentenary Foundation and was inaugurated in January 2012. The author wishes express his gratitude for the many useful comments on previous versions of this paper by the anonymous reviewers, Gustav Holmberg, members of the LETStudio, and Agustí Nieto-Galan, the commentator at the 8^th Science and Technology in the European Periphery conference at Corfu 2012. Finally, the author also wishes to express his gratitude to English language editor Allan Anderson, whose painstaking efforts have greatly contributed to the international presentability of this article.

Notes

¹ Gustav Holmberg, Reaching for the Stars: Studies in the History of Swedish Stellar and Nebular Astronomy 1860–1940 (Lund, 1999), ch. 3. Robert W. Smith, ‘Beyond the Galaxy: The Development of Extragalactic Astronomy 1885–1965, part 2’, Journal for the History of Astronomy, 40 (2009), 71–107. Lundmark's role in the discovery of the expansion of the universe has been recently discussed in Ian Steer, ‘Who Discovered Universe Expansion?’, Nature, 479 (2011), 171–3.

² On the Lick school, see Robert Smith, The Expanding Universe: Astronomy's ‘Great Debate’, 1900–1931 (Cambridge, 1982), 27.

³ Knut Lundmark, The Relations of the Globular Clusters and Spiral Nebulae to the Stellar System: An Attempt to Estimate their Parallaxes (Stockholm, 1920).

⁴ Knut Lundmark, ‘The Motions and the Distances of Spiral Nebulae’, Monthly Notices of the Royal Astronomical Society, 8 (1925), 887–94; idem, ‘Internal Motions of M 33’, Astrophysical Journal, 63 (1926), 67–71; and idem, ‘The Determination of the Curvature of Space-Time in de Sitter's World’, Monthly Notices of the Royal Astronomical Society, 84 (1924), 747–70.

⁵ The manuscript ‘I Stjärnans Skugga: Ett Filmmanuskript’ was not awarded in the competition. Lundmark later sent an English translation to Hollywood director Cecil B. DeMille under the title ‘In the Shadow of the Star, MS for a Film’. DeMille, however, also turned it down. Both manuscripts are kept in the Knut Lundmark Archive, Lund University library. See also Johan Kärnfelt, ‘I Stjärnans Skugga’ [In the Shadow of the Star], Lychnos: Årsbok för Idé- och Lärdomshistoria (Uppsala, 2009), 255–82.

⁶ Johan Kärnfelt, Allt mellan Himmel och Jord: Om Knut Lundmark, Astronomin och den Publika Kunskapsbildningen [Between Heaven and Earth: On Knut Lundmark, Astronomy and the Public Apropriation of Science] (Lund, 2009), ch. 1.

⁷ Jeff Howe, ‘The Rise of Crowdsourcing’, Wired Magazine, 2006 (retrieved 21 August 2012 from http://www.wired.com/wired/archive/14.06/crowds.html). See also Jeff Howe, Crowdsourcing: Why the Power of the Crowd is Driving the Future of Business (Three Rivets, 2008).

⁸ Andrea Wiggins and Kevin Crowston, ‘From Conservation to Crowdsourcing: A Typology of Citizen Science’, 2011 (conference paper retrieved 21 August 2012 from http://voss.syr.edu/content/conservation-crowdsourcing-typology-citizen-science), 1.

⁹ Examples can be found at such portals as http://www.crowdsourcing.org and http://www.dailycrowdsource.com.

¹⁰ For more information, see http://www.galaxyzoo.org, http://www.setiathome.berkeley.edu, and http://www.stardustathome.ssl.berkeley.edu.

¹¹ Patrick W. McCray, Keep Watching the Skies!: The Story of Operation Moonwatch and the Dawn of the Space Age (Princeton, 2008).

¹² See Thomas R. Williams and Michael Saladyga, Advancing Variable Star Astronomy: The Centennial History of the American Association of Variable Star Observers (Cambridge, 2011).

¹³ See Thomas R. Williams, Getting Organized: A History of Amateur Astronomy in the United States (Houston, 2000), ch. 5; and Martin Beech, ‘The Millman Fireball Archive’, Journal of the Royal Astronomical Society of Canada, 97 (2003), 71–7. Activities within other scientific disciplines that have many traits in common with crowdsourcing have been studied in e.g., Susan Leigh Star and James R. Griesemer, ‘Institutional Ecology, ‘Translations’ and Boundary Objects: Amateurs and Professionals in Berkeley's Museum of Vertebrate Zoology, 1907–39’, Social Studies of Science, 19 (1989), 387–420; Jeremy J. D. Greenwood, ‘Citizens, Science and Bird Conservation’, Journal for Ornithology, 148 (2007), 77–124; and Rebecca J. McLain, Harriet Christensen and Margaret A. Shannon, ‘When Amateurs are the Experts: Amateur Mycologists and Wild Mushroom Politics in the Pacific Northwest, USA’, Society & Natural Resources: An International Journal, 11 (1998), 615–26.

¹⁴ R. Bonney et al., Public Participation in Scientific Research: Defining the Field and Assessing its Potential for Informal Science Education, A CAISE Inquiry Group Report (Washington, DC, 2009). Another typology is given in Andrea Wiggins and Kevin Crowston (ref. 8).

¹⁵ It appears that Lundmark regularly supplied Nielsen with data from Swedish observers, particularly concerning bright fireballs. Although Lundmark's crowdsourcing initiative is not explicitly discussed in the letters, Nielsen does underscore the importance of the Swedish public being on the lookout for meteors and also sends a guide that he wrote on the making of meteor observations. See e.g. Axel V. Nielsen to Knut Lundmark, 27 April 1934, and Knut Lundmark to Axel V. Nielsen (concept), 21 March 1936, Knut Lundmark archive, Lund university library. An article mentioning the collaboration with Lundmark can be found in Axel V. Nielsen, ‘Über zwei Meteore (1936 März 12 und Dez. 1)’, Astronomische Nachrichten, 265 (1938), 354–66. Many years later Nielsen summarised his work in Axel V. Nielsen, Catalogue of Bright Meteors (Aarhus, 1968).

¹⁶ The exception is Bertil Anders Lindblad (1921–2010), who actually wrote his dissertation on the subject of meteors and later became a leading expert in the field. Lindblad, however, defended his dissertation in 1956, a year after Lundmark's retirement and many years after the meteor initiative. Moreover, even if his dissertation did contain data from visual observations of the Perseid meteors, these had been made by a small group of qualified observers associated with the Lund Observatory and not the general public. See Bertil Anders Lindblad, Combined Visual and Radar Observations of Perseid Meteors (Lund, 1956).

¹⁷ This was mainly done with the aid of a card catalogue that Lundmark kept on his popular articles. The catalogue, preserved in his archive, covers the years 1915 through 1939. If more examples exist, they would most likely be from the early 1940s.

¹⁸ For a lengthy discussion on the Swedish adult education movement see Johan Kärnfelt, Mellan Nytta och Nöje: Ett Bidrag till Populärvetenskapens Historia i Sverige [Between Utility and Delight: A Contribution to the History Popular Science in Sweden] (Stockholm & Stehag, 2000). An English summary can be found in Johan Kärnfelt, ‘The Popularisation of Astronomy in Early Twentieth-Century Sweden: Aims and Motives’, in Popularising Science and Technology in the European Periphery, 1800–2000, edited by Faidra Papanelopoulou, Agustí Nieto-Galan and Enrique Perdiguero (Aldershot, 2009), 175–94 (see especially p. 175–80).

¹⁹ For further information on the University extension movement see J. Rée, ‘Idealism and Education’, History of Education, 9 (1980), 259–63; and Stuart Marriott, ‘The University Extension Movement and the Education of Teachers 1873–1906’, History of Education, 10 (2006), 163–77.

²⁰ The development of a scientific citizenship in Sweden is discussed in Fredrik Bragesjö, Aant Elzinga and Dick Kasperowski, ‘Continuity or Discontinuity? Scientific Governance in the Pre-History of the 1977 Law of Higher Education and Research in Sweden’, Minerva, 50 (2012), 65–96.

²¹ I have previously used this material in a study on the public appropriation of science (Johan Kärnfelt, ref. 6). A similar study has been recently published in Susana Biro, ‘Astronomy by Correspondence: A Study of the Appropriation of Science by the Mexican public (1927–1947)’, Science Communication, 20 (2012), 1–17. It concerns the correspondence between the geographer and astronomer Joaquín Gallo and the Mexican public.

²² All quotes from primary sources have been translated into English by the author. My primary aim in doing so has been communication, and thus I have made no attempt to include misspellings, grammatical errors, dialectical expressions or old time Swedish; nor have I adopted an overly literal approach.

²³ Knut Lundmark, ‘Astronomiska Observationer, Lämpliga för Innehavare av Mindre Instrument: Några Råd och Anvisningar till Amatörer’ [Astronomical Observations, Suitable for Keepers of Small Instruments: Some Advice and Instructions to Amateurs], Tidskrift för det Svenska Folkbildningsarbetet, 4 (1915), 207–16. In this article, meteor observations are presented as one of a number of areas in which amateurs can participate.

²⁴ See e.g. Alan Chapman, The Victorian Amateur Astronomer: Independent Astronomical Research in Britain, 1820–1920 (Chichester, 1998); Thomas R. Williams, Getting Organized: A History of Amateur Astronomy in the United States (Houston, 2000); and Agustí Nieto-Galan, ‘“… not Fundamental in a State of Full Civilization”: The Sociedad Astronómica de Barcelona (1910–1921) and its Popularization Programme’, Annals of Science, 66 (2009), 497–528. One of the questions to be researched in the ongoing project mentioned in the Acknowledgement is why Sweden lagged behind in the area of amateur astronomy. Preliminarily, however, one can say that there are a number of factors that might have had a bearing on the case. To begin with, Sweden lacked ‘grand amateurs’ like those in Britain (Chapman) to inspire and take the lead. Furthermore, it was not until the establishment of the Swedish Astronomical Society in 1919 that Sweden had a national organization capable of promoting amateur astronomy. Lastly, none of 19^th century Sweden's professional astronomers, most of which specialized in celestial mechanics, appear to have been interested in amateur astronomy. This state of affairs changed at the turn of the century with a new generation of astronomers and the introduction of astrophysics.

²⁵ 'Observationer av meteorer, äro utav det allra största värde för den astronomiska forskningen, därför att ett flertal av dess problem, vilka ännu väntar på sin lösning, kunna verksamt befordras endast genom erhållandet av nya serier av iakttagelser och bearbetningen av dessa. Observatorierna och de astronomiska institutionerna hava i de allra flesta fall varken tid eller möjlighet att ägna någon större uppmärksamhet meteoriakttagelserna. Dessa kunna dock utföras utan några som helst instrumentella hjälpmedel, och de uppöva på grund av fenomenens kortvarighet observationsförmågan och iakttagelseskärpan på ett alldeles förträffligt sätt’, Knut Lundmark, ‘Iakttagelser av Meteorer: En Apell till Svenska Amatörer’ [Observations of Meteors: An Appeal to Swedish Amateurs], Populär Astronomisk Tidskrift, 8 (1927), 156–73 (156), Lundmark's italics.

²⁶ For the history of meteor astronomy see Mark Littmann, The Heavens on Fire: The Great Leonid Meteor Storms (Cambridge University Press, 1998); Martin Beech, ‘The Makings of Meteor Astronomy: Part I-IX’, Journal of the International Meteor Organization, 23–7 (1995–99); and D. W. Hughes, ‘The History of Meteors and Meteor Showers’, Vistas in Astronomy, 26 (1982), 325–45.

²⁷ Lundmark had previously discussed this topic in Knut Lundmark, ‘The Motions and the Distances of Spiral Nebulæ’, Monthly Notices of the Royal Astronomical Society, 85 (1925), 876–7. The argument in the amateur guide retraces the argument in the article.

²⁸ Carl Wirtz, ‘De Sitters Kosmologie und die Radialbewegungen der Spiralnebel’, Astronomische Nachrichten, 222 (1924), 21–26 (21). This issue was later researched by Axel Corlin, one of Lundmark's former PhD students. Cf. ref. 60.

²⁹ Knut Lundmark, (ref. 25), 157.

³⁰ Similar maps had been circulated to the members of the Society in 1920, but there is no evidence suggesting that they were re-circulated after Lundmark's article.

³¹ The basic design of the meteoroscope goes back to antiquity, but Lundmark discusses the modern design of M. Davidson, the head of the meteor section of the British Astronomical Association. For the early history of this instrument see J. D. North, ‘Werner, Apian, Blagrave and the Meteoroscope’, The British Journal for the History of Science, 3 (1966), 57–65, and for a discussion on a modern version see A. McBeath, ‘The Challis “Meteoroscope”’, WGN, Journal of the International Meteor Organization, 32 (2004), 141–2.

³² Karin Nordberg, Hör Världen!: Röst och Retorik i Radioföredragen: Populärvetenskap på Programmet [Hear the World!: Voice and Rhetoric in the Radio Lectures: Popular Science on the Air] (Umeå, 2003). Cf. Åsa Gillberg, ‘Archaeology on the Air: Radio and Archaeology in Sweden 1925–1950’, Current Swedish Archaeology, 14 (2006), 25–45.

³³ Knut Lundmark, ‘Bombardemang från Himlen’ [Bombardment from Heaven] (manuscript kept in the Knut Lundmark Archive, Lund University library, 1935).

³⁴ The lecture actually employed material from a previous newspaper article: Knut Lundmark, ‘Vår Bombarderade Jord’ [Our Bombarded Earth], Göteborgs Handel- och Sjöfarts-Tidning, 1 March 1934.

³⁵ ‘Ja, men havet är så stort, så stort och jag så liten, så liten’, Göteborgs Handel- och Sjöfarts-Tidning, 1.

³⁶ ‘Bättre kan man väl ej uttrycka människans känsla av hjälplös litenhet inför världen. Men det är inte bara denna känsla, som gör sig gällande, när vi någon gång tänka på den värld, som vi leva i. Vi ha säkerligen alla dagligdags gjort den erfarenheten, att ett av konfirmationens ord, som ledsagat oss ut i livet, nämligen att vi skulle ut i en farlig värld, innebära en mycket stor sanning. Däremot ha kanske ändå inte alla av oss därvid tänkt på en av de farligheter, som vår planet ständigt är utsatt för, nämligen ett oavlåtligt bombardemang från rymden i form av järnbitar, större och mindre stenar, sand- och gruskorn, jordkokor, och säkerligen också isbitar, ja, stundom även väldiga klippblock’, Göteborgs Handel- och Sjöfarts-Tidning, 1.

³⁷ According to Lundmark, this investigation was based on a catalogue of 1100 meteorites; it was never published, however, and the catalogue has not been preserved.

³⁸ ‘i flera fall äro fullt ut värda sin vikt i guld’, Knut Lundmark (ref. 34), 3. Several listeners took this statement literally and immediately wrote to Lundmark about some strange stones that they had found, bluntly asking where they could collect the money. The stones in such cases, however, never turned out to be authentic meteorites.

³⁹ ‘Allmänheten och pressen utföra genomgående ett berömvärt arbete, när det gäller att lokalisera och tillvarataga meteoriter. Någon gång uppstå svårigheter, enär våra offentliga samlingar icke kunna anslå alltför stora summor till inlösen av meteoriter, och ersättningsanspråken kunna stundom bli höga, enär både markägaren och flera fyndmän göra anspråk på betydande ersättning’, Göteborgs Handel- och Sjöfarts-Tidning, 7.

⁴⁰ ‘såväl av eldkulor som av meteorer äro ytterst värdefulla och välkomna’, Göteborgs Handel- och Sjöfarts-Tidning, 10.

⁴¹ ‘Över huvud taget kan det ej nog betonas huru viktigt det är vid alla meteoriakttagelser att uttrycka måtten i gradmått. Sådana meddelanden som man ofta får, att meteorens bana var “lång som en telegrafstolpe”, “en käpp” eller “en km lång”, äga ingen mening, så länge man ej vet avståndet till meteoren, och detta känner man i regel icke. Man bör också lära sig, att solens och månens genomskärning är mycket nära en halv grad och att avståndet mellan Castor och Pollux är 4.5 grader, mellan α and β Persei 10 grader och mellan Capella och Castor 30 grader’, Göteborgs Handel- och Sjöfarts-Tidning, 11.

⁴² Martin Eriksson, ‘En Ljusstark Eldkula’ [A Bright Fireball], Populär Astronomisk Tidskrift, 11 (1930), 75; Carl Strømer, ‘Norrsken och Eldkula’ [Aurora and Fireball], Populär Astronomisk Tidskrift, 12 (1931), 153.

⁴³ Meteor astronomy never became a major activity within Swedish amateur astronomy, and even at its height, never came close to such programs as the Canadian one mentioned above (ref. 13). When the Swedish Astronomical Society created a number of amateur divisions in 1960, the meteor division attracted only a couple of members and closed soon thereafter. In the 1970s the Scandinavian Union of Amateur Astronomers, in which Swedes were well represented, had better luck and managed to support quite a lively meteor division for some years before the union collapsed in 1982.

⁴⁴ The so-called Dala-meteor of 22 September 1936 represents a similar case. This very bright fireball created quite a stir in the newspapers, especially since there had been rumours of a meteorite fall. The meteor passed in a northwest direction some hundred and seventy kilometres north of Stockholm (near the city of Gävle), becoming the responsibility of a young amanuensis named Erik Johansson at Uppsala observatory. Johansson later published an elaborate report in Populär Astronomisk Tidskift, in which he states that he received 129 reports. Cf. Erik Johansson, ‘Eldkulan den 22 September 1936’ [The Fireball 22 September 1936], Populär Astronomisk Tidskrift, 18 (1937), 93–118.

⁴⁵ Knut Lundmark, ‘Stjärnfallen, deras Betydelse och Sättet för deras Iakttagelse’ [Meteors, their Role and the Way to Observe Them], Korrespondens: Hermods Månadstidning, 31 (1932), 156–9. The article was an addition to a correspondence course in astronomy that Lundmark supervised. I haven't managed to locate the actual letters but the article states that several of them discussed meteors and meteor observations.

⁴⁶ ‘som troligen kan vara av intresse för forskare att känna till’. J. H. Lundgren to the editor of Korrespondens, 17 November 1932 (Knut Lundmark archive, Lund University library).

⁴⁷ ‘Den 1:a började i stj. Bild. Lejonet, den 2:a gick genom Lyran, 3:e o¯ 5:e genom övre delen av Herkules, 4:e genom mitten av Björnvaktaren. Samtliga gingo kollosalt [sic] snabbt, syntes omkr. ¾ sek., på en sträcka motsv. nuv. avståndet mellan Mars o¯ Jupiter. Ljusstyrkan är svår att taxera, det var som sagt bländande månsken, men ‘ljusbandets’ bredd kan möjligen jämföras med Jupiters diameter. De föreföllo även ovanligt nära. Sedan efter en min. uppehåll följde ytterligare en, denna gång genom Kronan. Denne gick dock i O.N.O. riktning, alla de föregående i N.N.O.’ To simplify the translation the many abbreviations used by Lundgren have been spelled out, Korrespondens.

⁴⁸ ‘observationer icke äro alldeles värdelösa för vår oroliga världsrymds utforskare’, Korrespondens.

⁴⁹ ‘Vid den lektion, som började kl. 8 märkte jag strax efter lektionens början att elevernas uppmärksamhet icke var i samma utomordentliga grad riktad på hr lektorns undervisning, som annars alltid är fallet och fick efter förfrågan till svar, att man skådade ett underbart “sken” på himlen, varpå vi sorgligt att säga övergåvo den utstakade vägen och övergingo till celesta observationer’, Hjalmar Mandal to Knut Lundmark, 19 September 1935 (Knut Lundmark archive, Lund University library).

⁵⁰ ‘vilkas uppmärksamhet mindre än de övrigas distraherades av mannen i katedern’, Korrespondens.

⁵¹ ‘från en listigt vald fönsterplats’, ibid.

⁵² ‘det tjänar något till’, Korrespondens.

⁵³ ‘För den händelse icke senare forskningar redan givit ex. på längre tid har jag velat påpeka detta fall’, Korrespondens.

⁵⁴ ‘Kl 6.45 i fredagskväll den 2/11 1934 visade sig en helt liten stjärna i sydostlig ricktning, – (Jag var ute så jag iaktog [sic] det) – i detsamma när den visade sig exploderade den, då den lyste till som en sol, men dovt (som långt borta) med dock synbarligen. Vad skedde? Bedes vara vänlig att tala om det vid ett lämpligt tillfälle i Radio’, Sven Isaksson to Knut Lundmark, 2 November 1934 (Knut Lundmark archive, Lund University library). For clarity typos have been corrected in this and the following quote.

⁵⁵ ‘Vad tager stjärnorna vägen vid ett stjärnfall? [/] Vad menar man, då man säger: nu föll en stjärna från himlen? [/] Vad syftar meteor på, vad har ordet för betydelse? [/] Man talar om meteorstenar, vad består de av? [/] Kan man något utläsa på dessa, materiens byggnad och sammansättning? [/] Kan man kanske komma på villovägar, då vi veta att ämnen förvandlas, då de i smältande tillstånd föres från en lufttom rymd, till jordens atmosfär? [/] Vad spårar stjärnorna om vår värld, kan man bliva så kunnig att man av dem kan förutläsa [sic], dena [sic] Jordens undergång? Eller är det bara en tom fras av gamal [sic] Egyptisk lärdom? [/] Eller besitter stjärnorna, en viss karaktär, vad säger di oss?’, Korrespondens.

⁵⁶ ‘Ett eldklot med en eldkvast efter sig, sågs gå over himlavalvet från norr till söder, den 27 juli kl. 21.34. Från platsen där den sågs och till det ställe där den precis slocknade ut, beräknas till omkring tre till fyra hundra meters bana. Eldklotet hade ett ljusrött sken, samt av en knuten hands storlek. Himmlen [sic] var molnfri och klar’, Stina Axelsson to Knut Lundmark, 27 July 1940 (Knut Kundmark archive, Lund University library).

⁵⁷ ‘Om det vore möjligt vid tillfällen sådan som dessa att ange riktningarna någorlunda noggrant, t.ex. för början och slutet av fenomenet, så vore det ännu bättre. Riktningarna längs horisonten kan man ta ut med en kompass, eller få en ungefärlig riktning genom att gå ut ifrån, vad man på sin hemhorisont vet om nord-, syd-, väst- och östriktningen. Vad vinkelhöjden över horisonten angår, kan man åtminstone få ett grovt mått på den genom att använda sig av militärernas ‘fingermått’. Ni har alldeles säkert någon militär person i Er närhet eller bekantskapskrets, som kan förklara närmare, hur man använder fingrarna i det militära. [/] I ett fall som detta vore det också värdefullt att veta, så noga det går att uttrycka, hur pass nära zenit som eldklotet passerade. [/] Ja, detta var några små önskemål för framtida iakttagelser av detta slag. Glöm heller inte, att anteckningar om riktningar och dylikt måste göra med samma! Minnet kan man ej lita på!’, Knut Lundmark to Stina Axelsson (concept), 10 August 1940 (Knut Lundmark archive, Lund university library).

⁵⁸ Bruno Latour, Science in Action (Cambridge, MA, 1987), 227.

⁵⁹ Axel Corlin, ‘A Preliminary Report on Fireballs Observed in Southern Sweden on May 27, 1938’, Popular Astronomy, 47 (1938), 526–37.

⁶⁰ Those studies were later published as Axel Corlin, ‘On the Building up of Larger Bodies from Small Particles in Interstellar Space’, Zeitschrift für Astrophysik, 18 (1939), 1–24; and idem., ‘On the Existence of Obscuring Matter in the Vicinity of our Solar System’, Zeitschrift für Astrophysik, 11 (1936), 221–59.

⁶¹ E.g. Axel Corlin to Knut Lundmark, 24 July 1938 (Knut Lundmark archive, Lund University library).

⁶² One newspaper example can be found in Axel Corlin, ‘Dubbel Meteorit [sic] över Skåne på Fredagskvällen’ [Double Meteorite [sic] over Skåne on Friday Evening], Sydsvenska Dagbladet, 28 May 1938.

⁶³ Axel Corlin (ref. 59), 526 and 537. The organization and financing of the expedition is discussed in several letters between the two. See e.g., Axel Corlin to Knut Lundmark, 6 and 24 July 1938 (Knut Lundmark archive, Lund University library).

⁶⁴ Axel Corlin (ref. 59), 526.

⁶⁵ Axel Corlin (ref. 59), 527. Interestingly enough, Corlin's data contains 33 reports that mention hearing a hissing noise following the meteors. Some observers even heard the noise first and then turned around to see the meteor. Such a phenomenon has been widely reported, but only recently accepted as an actual physical effect. See Collin Keay, ‘Continued Progress in Electrophonic Fireball Investigations’, Earth, Moon and Planets, 68 (1995), 361–8, and Martin Beech, ‘The Millman Fireball Archive, part II: Sound Reports’, Journal of the Royal Astronomical Society of Canada, 98 (2004), 34–41.

⁶⁶ The Dala-meteor mentioned in ref. 44 can be regarded as the normal case. A modern example is the Buzzard Coulee meteorite, which fell in Canada on November 20, 2008. The first report came in minutes after the event and resulted in well over 400 reports during the following week (Martin Beech, ‘The Buzzard Coulee Meteorite Fall’, Meteorite Magazine, May issue, 2009). An important difference between historical and contemporary examples is that today bright fireballs also tend to be captured on video, as was made clear in the recent meteor event at Chelyabinsk, Russia. On the use of video for determining meteor trajectories see, for example, P. Brown et al. ‘The Orbit and Atmospheric Trajectory of the Peekskill Meteorite from Video Records’, Nature, 367 (1994) 624–6.

⁶⁷ Axel Corlin (ref. 59), 530.

⁶⁸ See http://www.zooniverse.org.

⁶⁹ Carolin Cardamone et al., ‘Galaxy Zoo Green Peas: Discovery of a Class of Compact Extremely Star-Forming Galaxies’, Monthly Notices of the Royal Astronomical Society, 399 (2009), 1191–205.

⁷⁰ Susan Leigh Star and James R. Griesemer (ref. 13), 407.

⁷¹ For a discussion of the concept of boundary object, see ibid.