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251 Years Later: Who Really Discovered Venus' Atmosphere?

Reproducibility forms one of the cornerstones of physics; independent scientists need to corroborate a finding before it's widely accepted in the scientific community.

But sometimes the window of observation only lasts for several hours twice every hundred years or so. That makes reproducibility fairly difficult.

Earlier this summer, Venus passed in front of — or transited — the sun for the last time this century. While the astronomical event amazed viewers across the world, a group of physicists were re-creating an observation from over 250 years ago: the discovery of Venus' atmosphere. At the same time, they've stoked the fire in a debate over who first made this discovery.

The entire Venus transit of 2012 in one image. Image courtesy of NASA.

In 1761, Mikhail Lomonosov, a Russian astronomer, watched as Venus completed one of its extremely rare transits of the sun. While hundreds of astronomers across the globe were anticipating this historic event, many did not expect what Lomonosov would soon observe.

As Venus transited the sun, Lomonosov noticed that the sun's light seemed to form a bulge around Venus. This observation suggested that something must have been changing the direction of the sun's light. Who was the culprit? A Venetian atmosphere, according to Lomonosov.

Lomonosov argued that molecules in a hypothetical atmosphere surrounding Venus could change the light waves' direction through refraction. When light passes through a new medium (e.g. water or an atmosphere), it will bend in a new direction. This phenomenon causes sticks to appear bent when submerged in water and leads to the distorted reflections seen in water droplets.

Lomonosov made this discovery with some bare bones equipment: a 4.5 foot long telescope made in the 18th century. But not everyone thinks Lomonosov should get the credit for this discovery. During the 2004 transit of Venus, Scientists who used slightly more sophisticated instruments than those available to Lomonosov had trouble reproducing Lomonosov's results. Consequently, Fermilab physicist Vladimir Shiltsev and his colleagues decided to re-create this experiment in June with the closest replicas of Lomonosov's telescope that they could find.

One of the telescopes used for the June, 2012 re-creation of Lomonosov's original observation. Image courtesy of Koukarine et al. via their arXiv article.

Shilstev and his team pored over Lomonosov's original texts to create two new telescopes that would closely match what he had in 1761. Lomonosov's original telescope was lost during a bombardment in WWII.

After finding the necessary supplies and creating their rudimentary telescopes, two team members positioned themselves in Illinois and California for the 2012 transit, respectively. Although clouds obscured their view for part of the transit, they both saw the same refraction that Lomonosov observed over 250 years ago. Apparently, Lomonosov didn't make it up! Or he at least had the right tools to make his claim.

The characteristic light "whisker" indicating that light has been refracted as observed from the Illinois telescope during the June, 2012 transit. Image courtesy of Koukarine et al. via their arXiv article.

Scientists, of course, had already verified the existence of Venus' atmosphere through other means. But now we know that Lomonosov likely could have observed Venus' atmosphere through refraction back in 1761, just as he reported.

Now there's more evidence to support Lomonosov as the original discoverer of a Venetian atmosphere. I doubt we've heard the end of this story, though. Stay tuned for the next transit in 2117 for new developments, or maybe tell your grandchildren to watch for you.

The full arXiv preprint article can be found here.

For more background on Lomonosov and his original discovery, take a look at this conference talk (PDF) by Mikhail Marov from 2004.


If you want to keep up with Hyperspace, AKA Brian, you can follow him on Twitter.


  1. see another of experimental
    archeology applied to the
    history of the physical
    sciences here - "Optical
    quality of Galileo's lenses":

    ...seems that antique instruments
    (telescopes in this case) were
    not that bad while the wit and
    experimental skills of researchers which were just
    outstanding (if we're talking
    about Lomonosov and Galileo)

  2. Actually, the lenses tested in the given article are not made by Galileo! They are replacement lenses made in much later time...


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