Did Lomonosov see the Venusian atmosphere?

Shiltsev replies: The criticism of Jay Pasachoff and William Sheehan does not appear well founded. First, besides Mikhail Lomonosov, who was the first to recognize and explain the aureole around Venus, several other astronomers had seen it, too, during the 1761 and 1769 transits. The 18th-century images of the “Lomonosov arc” do not have the resolution of those taken nowadays from space satellites, but neither do most of the images that were taken by ground-based telescopes battling our atmosphere during the transits of the late 19th century, 2004, and 2012.

Also, I think the proportion of Lomonosov’s paper that was devoted to the observations is perhaps a red herring. That he wrote 5 out of 16 pages placing his results in the intellectual context of his day is a testament to his abilities as a natural philosopher; the plurality of worlds was as hot a topic then as it is in our age of exoplanet research.

To address the skepticism, my colleagues and I experimentally replicated Lomonosov’s discovery during the transit of Venus on 5–6 June 2012. A thin arc of light on that part of Venus off the Sun’s disk during the ingress was successfully detected with original 18th-century Dollond achromatic refractors similar to the one deployed by Lomonosov and with his experimental techniques carefully emulated. ¹ Simultaneous observations with high-quality modern doublet refractors revealed the aureole, too, and demonstrated that today’s telescopes do not significantly outperform the earlier instruments. ²