An International Celebration of the 150th Anniversary of Mars’s Great Opposition of 1877, 
and All It Brought

The year 2027 will mark 150 years since the great Mars opposition of 1877, at which Asaph Hall discovered the moons, David Gill observed the parallax in order to try to determine the length of the astronomical unit from Ascension Island, and—most relevant here—Giovanni Schiaparelli at the Brera Observatory and Nathaniel Green at Madeira produced rival maps of Mars.  They could hardly have been more different–and this should have been a cautionary tale, as it suggested that perhaps subjective/stylistic effects were important in what was reported by different observers at the eyepiece.  In the end, Schiaparelli’s schematic map was far more influential than Green’s, and so the canals burst upon the scene—and with them a preoccupation with the possibility that Mars might be inhabited that would last for at least thirty years.
 
There will be an opposition of Mars (not very favorable) in February 2027, and initially, it was proposed by Jean Guerard of the Société Astronomique de France (Juvisy Observatory) and Todd Gonzales (Lowell Observatory) that some kind of joint observing session could be held at these respective observatories for the opposition. While the initial suggestion was for a single event, as the conversation expanded it became clear that the canals of Mars and the era of planetary astronomy they represented was likely to attract wide interest, and so we began as a small group (including also Sarah Anderson and Paolo Tanga at Nice Observatory) to explore the possibility of doing a series of events running from February through September (the anniversary of Mars’s 1877 opposition) held at various institutions, with talks, art presentations, wine tastings, as well as observing opportunities with classic telescopes featured.  These meetings would be broadcast by Zoom or other technology around the world from the locations at which they were held.