In anticipation of Monday’s total eclipse, this week we’ve got a series of excerpts from the Svalbard chapter of Out in the Cold, in which we traveled up to 800 miles from the North Pole in search of totality in March, 2015. Get a copy of the whole book for yourself, or order the unabridged audiobook.
FIGURING OUT ECLIPSES
Besides being tiny bits of land surrounded by oceans, Svalbard and the west African island of Principe share vanishingly little, but just like the Solar Wind Sherpas are doing on Svalbard this week, a hardy team of British scientists set out a hundred years ago to made eclipse history on Principe.
On 8 March, 1919 Sir Arthur Stanley Eddington and his party sailed from Liverpool bound for the equator, and just north of there, on 23 April, landed in the Gulf of Guinea on a small, humid, buggy island around a hundred twenty miles west of the African coast.
Albert Einstein’s audacious 1915 theory of general relativity sorely needed testing. If it were proven right it would mean that space and time are pliable as the surface of a trampoline, twisting and bending all over the place.
Relativity predicted that light need not always travel straight, but rather should warp as it passes the gravitational field of an object in space, like the sun. But how to measure such a thing?
If light from stars behind the sun were bent by the sun’s gravitational field, those stars’ apparent position might be distorted so that they became visible. Their apparent position should be different from their position in the sky at night, when the sun is far away on the other side of the Earth.
But how to see behind the blinding light of the sun? Perhaps with the help of the moon, during an eclipse.
Two years after publication of Einstein’s theory, the British Astronomer Royal Sir Frank Watson Dyson worked out that during the eclipse of 29 May, 1919, the sun would cross the Hyades, a cluster of stars near enough that there would be a number of stars bright enough to see through a telescope, and that the island of Principe would be a fine place to watch it.
Dyson sent Eddington to test Einstein’s theory.
Scientific cooperation between countries waxes and wanes as surely as celestial bodies. Freed from Soviet restrictions, in the 1990s Russian scientists rushed to collaborate with their counterparts, eager to compare their science with the West. Some of that collegiality has since lessened.
Similarly, by 1919 the Great War had severed lines of scientific communication. A Russian mathematician knew of Einstein’s work but couldn’t participate from behind the walls of a German prison. A German astronomer couldn’t test the theory from his perch at a Russian prison camp. A naval blockade kept German scientific journals from crossing the English Channel. To Eddington that was plain wrong.
Eddington learned of Einstein’s work through a middleman mathematician in neutral Holland, whom Einstein could visit.
A British scientist’s aggressive work on the theories of a German physicist kicked up controversy, especially as Eddington, a Quaker, claimed conscientious objector status and needed the help of Dyson, his boss the Astronomer Royal, to stay out of jail. Packing Eddington off to do science on a remote island for several months was just the thing.
Eddington: “The baggage was brought … mainly by tram, but with a break of about a kilometer, where it had to be transported through the wood by native carriers.”
The party set up their viewing station at latitude one degree forty minutes north, using “freely” the “ample resources of labour and material” available locally.
Eddington noted that “Near the center” of this tiny six-by-ten mile island, “mountains rise to a height of 2,500 feet, which generally attract heavy masses of cloud.”
And so they did. “The days preceding the eclipse were very cloudy. On the morning of May 29 (eclipse day) there was a very heavy thunderstorm….”
But “about half-an-hour before totality the crescent sun (partial eclipse) was glimpsed occasionally.”
It would have been an awfully long trip to have come back empty, but in the end “16 (photographic) plates were obtained … by moving a cardboard screen unconnected with the instrument.”
Eddington compared a set of “true” positions of the stars – photos he had taken of the same patch of sky when the sun was nowhere around – with the set of photos he took during the eclipse. He could confirm Einstein’s theory.
The day after Eddington announced his findings, the New York Times of 10 November, 1919, ran these headlines:
LIGHTS ALL ASKEW IN THE HEAVENS
Men of Science More or Less
Agog Over Results of Eclipse
EINSTEIN THEORY TRIUMPHS
Stars Not Where They Seemed
or Were Calculated to be,
but Nobody Need Worry.
Politics will forever hover over science. But in this case, right in the middle of the Great War, Arthur Eddington brought down barriers to advance the scientific standard, to explain Einstein’s theory and to spark the imagination of an otherwise war-distracted public.
As a bonus, the Eddington team saw the largest solar prominence to be seen at a total eclipse since. It extended some 100,000 kilometers beyond the surface of the sun.