Here Comes (and Goes) the Sun: 5 Shady Facts about Eclipses

Pssst... Hey, you! Have you heard that the sun is going to disappear from the sky momentarily, and be replaced by a giant shadow? And that this does not signify the end of the world? Relax, doomsday preppers—it’s just a solar eclipse, and they happen all the time. Well, not all the time, but a lot of the time. Well, maybe not as often as that. To be factual, they happen about twice a year.

Photographers, videographers, and hordes of spectators will be out soon, on October 14, 2023 and April 8, 2024, to witness the events and, if you haven’t read about it yet, check out our Solar Eclipse site for the best tips and tricks on how to photograph, film, or just see the event without burning out your eyeballs.

There was a time when this type of foreshadowing (pun intended) spelled out doom in capital letters for some but, nowadays, most people know that an eclipse is simply the moon passing in front of the sun. But did you now that a solar eclipse brings with it a laundry list of spectacular facts and fascinating details about which many are not aware? We’ve assembled a few of the better ones here for you to pass around at the eclipse with your family and friends.

1. It’s How We Found out the Earth was Round

Although many of us know that Christopher Columbus was not the only person in his generation to believe that the earth was round (let’s hope you knew that!), most people do not know that the original discovery of the earth’s shape was due to an eclipse. Aristotle, who lived in the 4th Century BCE, observed that the shadow the Earth projected onto the Moon during lunar eclipses was always curved. This observation led him to understand that the Earth is, in fact, round.

2. Eclipses Might Mess with Gravity

At the 1851 World’s Fair, Jean Bernard Leon Foucault demonstrated that a pendulum could track the rotation of the Earth, proving the Earth’s rotation without astronomical instruments for the first time.

In 1954, Maurice Allais released a Foucault pendulum every 14 minutes for 30 days and nights. (Serious commitment, am I right?) During the solar eclipse of that year, his pendulum changed its angle of rotation by 13.5 degrees. Allais hypothesized that this increase in gravity was due to the Moon’s screening effect on the gravitational attraction of the Sun.

However, what makes this observation even more interesting is the fact that this phenomenon has been tested many times over, and some of the tests have demonstrated the Allais Effect and some have not. So, as of now, this gravitational behavior is just a theory, but kind of a creepy one—I mean, try dropping a watermelon from your kitchen window during the eclipse and see if it floats. Report back with results.

3. Helium was Discovered because of an Eclipse

In the early 1800s, Francis Baily was fascinated by what we now call “Baily’s beads” (it was the early 1800s—people were fascinated by a lot of things that seem like NBD, like democracy and personal hygiene). This is when the sunlight streams through the mountains and valleys along the Moon’s edge at the first and last moments of a solar eclipse’s totality. Baily was sure that this phenomenon would reveal new information about the actual makeup of the Moon and Sun.

Baily’s interest fueled the curiosity of astronomers around the world, particularly Pierre Jules Janssen and Norman Lockyer. Both astronomers (independently) developed instruments to study the spectral lines of the Sun that are visible during an eclipse. They found that the light was composed of two bright red and blue lines and two weaker yellow and green lines. These lines indicate hydrogen, so without traveling to space, these scientists could discover the composition of the Sun years ahead of their time, disproving many scientists before them.

Furthermore, some of the spectral lines emitted lines like hydrogen, but with unique bright yellow auroras. Because Lockyer found no other element with a similar makeup, he proposed a new element: helium, something that would not be discovered on Earth for another 24 years, and would end up being a huge party trick and signal the advent of talking like a Munchkin from the Wizard of Oz. Oh, science.

4. Captain’s Log: Vulcan. Identified. Thanks to an Eclipse

For many years, scientists understood the orbits and motions of the planets based solely on Isaac Newton’s laws of gravity and motion. But these laws could not explain certain peculiarities in Mercury’s orbit. Therefore, the French mathematician Urbain Le Verrier (coolest scientist name ever) hypothesized that there was a planet between Mercury and the Sun. He named it Vulcan. And named his dog Spock (dog part not true).

When Albert Einstein published his General Theory of Relativity in 1915, he proposed that gravity was not a force between objects with mass, (take that Newton!), but rather a warping of the fabric of both space and time. Of course, he did, because... Einstein. The most perfect way to demonstrate, and thereby, prove Einstein’s theory was a total solar eclipse. Only by observing a solar eclipse could the bending of starlight passing near a mass like the Sun be observed.

Expeditions to measure the deflection of starlight in 1912 failed due to bad weather. The next expedition should have set out for Russia, in August of 1914, but Archduke Ferdinand’s assassination and the start of WWI forestalled the party and German-English relations during the war were disastrous for Einstein. Most scientists in England would not publish or even read the work of a German. One of the only English proponents for Einstein’s work was the astronomer Arthur Eddington. Therefore, shortly after the end of the war, Eddington traveled to Principe for an eclipse that would take place on May 29, 1919.

On November 6, 1919, Eddington announced to the Royal Astronomical Society and the Royal Society that Einstein’s theory had been confirmed. This had been achieved by photographing the Sun during a solar eclipse and comparing the plates with photographs of the night sky when the stars were in the same position without a solar eclipse. The starlight deflected about an arc-second in bearing—which basically meant that the whole Vulcan planet didn’t exist. And that was the end of the planet Vulcan until, of course, Gene Roddenberry came along and reinvented it.

5. We Used the Concorde to Chase an Eclipse

On June 30, 1973, the longest eclipse of a lifetime would occur above parts of Indonesia and the South Pacific: the eclipse’s totality would last 4 minutes and 9 seconds, but the full experience would last for 7 minutes and 4 seconds; only 28 seconds shorter than the longest possible eclipse viewable from Earth. Sunscreen sales plummeted (like Spock the dog, not true). At the time, the Concorde, a commercial airplane that could break the sound barrier, was nearing the end of a successful testing program. Astronomers in France and the UK realized that if they could fly the Concorde during the eclipse, they could essentially follow the shadow of the Moon. Because the Concorde could travel at almost the same speed as the eclipse itself, the scientists would have more than 70 minutes to watch the eclipse!

Scientist Pierre Lena was able to convince French pilot Andre Turcat to perform the mission. A team of scientists then worked hard to modify the plane, adding extra portholes in the roof of the Concorde, since the eclipse would appear directly above them. The expedition turned out to be a huge success, and Turcat flew the Concorde “001” at speeds of up to Mach 2.05, allowing the scientists to make observations for a total of 74 minutes. Vive la France!

So, there you have it—five fascinating facts about the eclipse you may not know. These should help you win any bar-related trivia contests, tall-tale seminars, or general bull sessions while you hang around and stare at the sky with family and friends. We hope these amusing and tantalizing pieces of information will offer some intellectual respite from the blinding light of our other eclipse articles.