The 1922 Wallal Eclipse That Tested Einstein

What the catalogue establishes

NASA's solar-eclipse catalogue lists a total solar eclipse on 21 September 1922, with a path crossing the Indian Ocean and Australia. That entry fixes the date and global geometry. Why this eclipse became internationally significant comes from the documented history of the expedition that went to observe it.

Why scientists needed a total eclipse at all

Einstein's 1915 general theory of relativity predicted that a massive body like the Sun would bend the path of light passing near it, by a specific, calculable amount. Ordinarily, starlight near the Sun is not observable because the Sun's own brightness overwhelms it. A total eclipse briefly removes that problem: with the photosphere fully covered, stars close to the Sun's position in the sky become visible and photographable, and their measured positions can be compared with their known positions when the Sun is elsewhere.

Wallal's place in testing relativity

Arthur Eddington's 1919 expeditions to Príncipe and Sobral produced the first eclipse-based measurements supporting Einstein's prediction, and made worldwide news. The 1922 eclipse offered a further, independent test with different equipment, a different observing team, and a different stretch of sky. An international expedition, including the Lick Observatory's director W. W. Campbell, travelled to Wallal on the Western Australian coast, in Nyangumarda Country, because the site sat directly in the path of totality with a reasonable expectation of clear September skies. The expedition's funding came from philanthropist William Crocker.

Campbell reported that the Wallal measurements agreed closely with Einstein's predicted deflection value, adding independent weight to the 1919 result at a time when general relativity was still being tested against competing explanations.

The other 1922 sites

The 1922 path crossed several places with observers. According to the Western Australian Museum, parties set up at Cordillo Downs in north-eastern South Australia, at Goondiwindi, Stanthorpe and Coongoola in Queensland, and on Christmas Island, where a party from the Greenwich observatory went; a site in the Maldives was also considered. Of all of them, the museum records, the plates taken at Wallal were the most successful, with excellent weather and an excellent view of the eclipse.

Thirty-five tonnes through the surf

Wallal Downs Station sits on Eighty Mile Beach, about 300 km south of Broome. The name means "sweet water", after a local Aboriginal fresh water source. In 1922 the settlement was a single building for four or five telegraph operators and linesmen, with shelters for more than 100 Aboriginal people. More than thirty people from the United States, Great Britain, India, Aotearoa New Zealand, Canada and Australia converged there: astronomers, photographers, naval staff and Aboriginal stockmen. Over three days they unloaded 35 tonnes of equipment from boats anchored off the beach, loaded it onto donkey trains and hauled it to the observing site, then camped on loose grey sand that, one account complained, found its way into the food and everything else.

Ten minutes' warning

On the day, a large gong sounded at 4:03 p.m. to warn the observers that ten minutes remained before second contact. Melbourne's Argus reported the moment the shadow arrived: it "seemed for an instant to be suspended below the western sky to sweep instantaneously outwards". The cameras were triggered the instant totality began; the whole experiment depended on a few minutes of exposures that could not be repeated.

Wallal and the 2028 path

Wallal is outside the 2028 path. Calculated from NASA's Besselian elements, Wallal Downs sees only a partial eclipse on 22 July 2028, and the nearest totality is about 600 km to the north-north-east, where the shadow reaches the Kimberley coast. Broome and Port Hedland are partial as well. The Kimberley regional guide covers where the 2028 shadow does come ashore.

What 1922 shares with 2028

The Wallal expedition faced, at a larger scale, the same problem as a remote 2028 eclipse trip: getting equipment and people to a place with no infrastructure, betting on the weather, and making a few minutes of totality count. Their answer was a site chosen for its sky rather than its convenience, and it paid off: Wallal had the best weather of the 1922 expeditions.

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Continue exploring

Compare this with Sydney's 1857 total eclipse and Dunedin's 1163 total eclipse, check the Kimberley region guide for the modern coastal corridor, read how eclipse geometry is calculated, or verify any coordinate on the interactive map.