The Aristarchus Campaigns: Collaboratively measuring the Solar System Best Practices Best Jorge I. Zuluaga Juan C. Figueroa Keywords FACom-Instituto de Física-FCEN, Universidad de FACom-Instituto de Física-FCEN, Universidad de Citizen astronomy, lunar orbit, lunar distance, Antioquia & Sociedad Antioqueña de Astronomía Antioquia & Sociedad Antioqueña de Astronomía Moon calculations, speed of light, astronomical Colombia Colombia methods, astrometry, citizen science [email protected] Summary Citizen astronomy has proven to be one of the most effective ways to actively involve amateur astronomers in real scientific endeavours. We present here the Aristarchus Campaigns, a citizen astronomy project intended to collaboratively reproduce historical astronomical observations. During the campaign amateur astronomers were invited to use simple optical instruments to gather data about some common astronomical phenomena. This data was used to calculate the value of well-known physical and astronomical quantities such as the speed of light and the distance to, and size of the Moon. We describe the project and the results of the first two Aristarchus Campaigns. We argue that this type of simple campaign may help to engage the public with astronomy in developing counties and prepare their astronomical communities to par- ticipate in high-impact observational campaigns. Introduction using powerful lasers and retro-reflecting Today, the advent of advanced and arrays of mirrors placed on the lunar sur- accessible technological devices such Ancient astronomers devised inventive face by the Apollo astronauts, so that the as smartphones is opening new doors methods to measure the Solar System. distance is now known to within just a few for do-it-yourself astronomy. Many per- Using these methods, which are in princi- centimetres (Tapley, 2004; Dickey, 1994). sonal electronic devices such as smart- ple very simple, we can measure the sizes The diameter of and distance to the Sun phones come with a GPS receiver, fast of the Sun, the Moon and the planets, and have been determined to one part in a internet connections and precise clocks. their distances from us. One of the best billion and one part in a 100 billion respec- This gives us, the science communicators, known of these ancient methods was orig- tively (Schou, 1997; Muhleman, 1969) an incredible opportunity to involve astron- inally proposed by Aristarchus of Samos and the speed of light, which until a few omy enthusiasts, and the wider public, in (ca. 310–230 BCE) who devised proce- decades ago had only been constrained astronomy projects. They allow for in situ dures that used lunar phases and eclipses using astronomical methods, is now reg- measurements that would otherwise be to estimate the relative sizes and distances ularly measured in the laboratory so pre- prohibitively expensive and available only of the Moon and the Sun (Van Helden, cisely that it is known to roughly one part to professional scientific teams. 2010; Heath, 2013). in a billion (Sullivan, 2001). This scientific and sociological phenom- More recently, physical constants have In contrast to the classical methods devised enon is called citizen astronomy, or more attracted the attention of astronomers. by such pioneers as Aristarchus or Rømer, generally, citizen science (Raddick, 2010). Using the huge spatial and temporal most of these modern techniques are far scales natural to astronomy, astronomers from the reach and technological capacity Our citizen astronomy campaigns aimed to have devised ingenious ways to measure of most amateur astronomers. Therefore, reproduce historical astronomical obser- the values of these physical constants. measuring distances in the Solar System, vations and measurements that helped to Take for example the method devised by and constraining the physical constants determine the size of the local Universe. Ole Rømer (1644–1710) who measured the that govern it, today seems to be a mat- Here, we will give a background to the speed of light in vacuum by observing the ter of sophisticated instrumentation and project and the role that citizen astronomy periodic occultation of the moon Io by its advanced scientific capabilities. But, these plays in science outreach; we describe host planet, Jupiter (Cohen, 1940). classical methods have a great deal left the project and the specific campaigns to offer and still find a privileged place in that we have run with the participation of Now, many centuries after the invention astronomy and physics textbooks. They individuals and communities in Colombia of these historical methods, astronomers are used today as educational tools, not and abroad; summarise some the most and physicists have measured these quan- only for teaching science history, but also important scientific results of the cam- tities with exquisite precision using vastly for teaching the methods of astronomy and paigns; and discuss the challenges more elaborate tools and methods. The physics and inspiring new ways of thinking involved when organising and running this distance to the Moon can be determined about the results (Salvador, 2009). kind of initiative. CAPjournal, No. 17, June 2015 23 The Aristarchus Campaigns: Collaboratively measuring the Solar System over a geographic area covering not only Colombia but several neighbouring coun- tries. The Aristarchus Campaigns On 15 April 2014 a total lunar eclipse was visible from most of the Americas and the Caribbean. Lunar eclipses are very com- mon phenomena that are spotted, photo- graphed, and even measured by hundreds of millions of observers. They provide well-known opportunities to measure the size of, and distance to, the Moon and the Sun, as recognised over two thousand years ago by Aristarchus of Samos (Heath, 2013). In 2014, a group of professional astrono- mers and astronomy undergraduate stu- dents at the University of Antioquia in Medellín, Colombia teamed up with the Sociedad Antioqueña de Astronomía — a regional astronomical association — and launched the Aristarchus Campaign. The campaign was intended to make the Figure 1. Screenshot of the iContact web-based application developed for the 5 July 2014 Aristarchus experience of observing the total lunar Campaign1. eclipse not only an enjoyable recreational activity, but also an opportunity to perform simple measurements using readily avail- The rise of citizen astronomy the past to study the evolution of comets, able astronomical equipment — such as measure the position of near-Earth aster- binoculars, small telescopes and cameras A recent, inadvertent example of the oids or observe the occultation of stars by — and personal electronic devices — like power of citizen astronomy took place Solar System objects (Ortiz, 2011). Projects mobile phones and tablets. on 15 February 2013. On a cold morning like these have led to new discoveries in Siberia, hundreds of thousands of and breakthroughs but, in most cases, The initiative was promoted by local citizens of several large cities around the the people enrolled in these campaigns astronomy clubs and through social net- Chelyabinsk region in Russia witnessed are experienced observers, whether works. An observing guide was written to only the second large asteroid impact professional or amateur. More simple observe and measure the lunar eclipse and ever recorded. Hundreds of pictures and astronomical campaigns, such as those the public in Medellin were encouraged to videos were taken that day by random described here, aim instead to measure submit their measurements and pictures observers and shared almost instantane- or to observe common astronomical phe- for potential scientific use. ously via social networks. The data col- nomena such as lunar and solar eclipses lected by these de facto citizen scien- and occultations, which use simpler and The weather in Colombia on the date of tists allowed professional astronomers more readily available instrumentation the eclipse made it very difficult for many around the world to study the phenome- and methods. These may serve as initial committed enthusiasts to perform most non in unprecedented detail (Brown, 2013; experiences for those who might then go of the measurements. However, despite Zuluaga, 2013). on to participate in more advanced pro- this slow start we were motivated by the jects. Mass participation in these simple enthusiastic response on social networks Another well-known citizen astronomy campaigns from communities in develop- and proposed, in the same year, several project is the Globe at Night project, a ing countries may prepare them for more similar campaigns. successful initiative intended to measure interesting and challenging collaborative light pollution around the world (Barringer, projects. We now call these observational initiatives, 2011). collectively, the Aristarchus Campaigns. In 2014, with all of this in mind, we designed At the time of writing, there have been three Collaborative astronomical observations and launched a new set of citizen astron- Aristarchus Campaigns: that involve many amateur and profes- omy projects in Colombia called the sional astronomers are not new (Meech, Aristarchus Campaigns. The projects 2005). These campaigns have been run in involved amateur astronomers distributed 24 CAPjournal, No. 17, June 2015 CAPjournal, No. 17, June 2015 Campaign 1: The 15 April 2014 campaign centred on the total lunar eclipse. Campaign 2: The 23 May 2014 campaign associated with the meteor storm of the 209P/Linear comet. Campaign 3: The