2022 Wallal Centenary - Australia Tests Einstein's Theory One Dollar ($1) Uncirculated Australian Decimal Coin

In 1922, the eyes of the international scientific community were focused on an expedition of scientists to Wallal, Western Australia to photograph a total eclipse due on 21 September. Precise measurements of the apparent position of the stars near the eclipsed Sun were photographed and provided the first evidence supporting Einstein’s revolutionary Theory of General Relativity.

The Royal Australian Mint commemorates 100 years since this significant scientific expedition took place in Australia.

100 years ago, there was little in Wallal, Western Australia except for a cattle station and a telegraph. Many scientists were sceptical about leading a complex scientific expedition to this remote location in Australia. However, the ideal viewing conditions of the eclipse and the enthusiasm of University of Western Australia-based leaders ensured the expedition progressed.

The expedition included teams from multiple countries as well as local astronomers from the Perth Observatory. The telescopes and photography equipment were bulky, heavy, and fragile and, after arriving by ship in Sydney, needed to be transported by rail to Fremantle. From Fremantle, a series of smaller boats took the teams to Broome, then eventually to Eighty Mile Beach and Wallal, where the equipment was unloaded in the surf and transported to shore. The team led by William Campbell from the Lick Observatory (USA) was successful in taking the images of the eclipse that became the first evidence to support Einstein’s theory.

Einstein’s theory states that massive objects, such as planets and stars, curve the fabric of space and time around them. The theory predicts that light from a distant star passing near the Sun will follow the curve as it travels to the Earth, making the star appear to be displaced in the sky; it even predicts by how much the stars will appear to be out of place! Normally stars near the Sun are overwhelmed by the bright sky but during a solar eclipse, the Moon obscures the Sun, creating a sky dark enough that stars can be photographed.

• The coin’s reverse features the Earth and Wallal, Western Australian prominently and with each sitting within a funnel depicting Einstein’s Theory of General Relativity.
  
  
• Packaged in a presentation card

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