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Solar eclipse and relativity — there is no Vulcan

This article “Solar Eclipse Science Helps Prove Einstein’s Relativity Theory in Nat Geo’s ‘Genius’” published on May 30, 2017, reminded me of the connection between the study of solar eclipses and Einstein’s theory of general relativity.

While the U.S. prepares for the Great American Total Solar Eclipse coming on Aug. 21, National Geographic’s “Genius” recounts how a solar eclipse helped to prove Albert Einstein’s theory of general relativity.

The latest installment of the new global event series airs tonight (May 30) at 9 p.m. EDT on the National Geographic Channel. In this episode, Einstein seeks funding for an expedition to see a total solar eclipse, because he believes that by observing stars near the sun, he can prove that gravity bends light.

The article contains a short promo for the National Geographic’s series. National Geographic has a clip “There is no Vulcan” from Chapter 6 of the series in which “Einstein explains his radical theory that the sun’s gravity bends light, disproving the existence of the planet Vulcan.”


The observation of a total solar eclipse of May 29, 1919, helped to confirm Einstein‘s theory of general relativity. By comparing the apparent distance between stars in the constellation Taurus, with and without the Sun between them, Arthur Eddington stated that the theoretical predictions about gravitational lenses were confirmed. The observation with the Sun between the stars was only possible during totality since the stars are then visible. Though Eddington’s observations were near the experimental limits of accuracy at the time, work in the later half of the 20th century confirmed his results. has a related article “Here’s What Scientists Have Learned From Total Solar Eclipses” published on May 17, 2017.

2 thoughts on “Solar eclipse and relativity — there is no Vulcan

  1. Speaking of relativity, this Live Science article “8 Ways You Can See Einstein’s Theory of Relativity in Real Life” published on March 14, 2017, summarizes how you may experience relativity in your home.

    The difference is very real: if no relativistic effects were accounted for, a GPS unit that tells you it’s a half mile (0.8 km) to the next gas station would be 5 miles (8 km) off after only one day.

    • Magnetism (in transformers and electric generators)
    • Electromagnets
    • GPS
    • Gold’s color
    • Gold’s resistance to corrosion
    • Liquid mercury
    • An old CRT TV or monitor
    • Light speed
  2. Speaking of observing eclipses, this June 9, 2017, article “How Scientists Predict the Path of the 2017 Total Solar Eclipse” discusses “how NASA scientists figure out exactly where the moon’s shadow will fall on the surface of the Earth, down to the city block.”

    Knowing where to watch the eclipse means the difference between seeing totality — when the sun is fully concealed by the moon — and just a partial eclipse, where the moon covers part of the sun but the sky doesn’t fully darken. If you’re outside the path of totality, the moon’s crossing will be just a glancing blow. [Total Solar Eclipse 2017: When, Where and How to See It (Safely)]

    Unlike 19th century methods which use some simplifications, modern techniques use elevation maps of both the Earth and Moon. Read the full article to check what the view will be in your area on August 21.

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