Australia is wider, coast to coast, than the diameter of the Moon.
Australia stretches roughly 4,000 kilometers from its westernmost point near Steep Point to its easternmost point in New South Wales. The Moon, by comparison, has a diameter of about 3,474 kilometers. That means the width of the Australian continent, measured east to west, is greater than the width of the Moon itself.
The comparison sounds implausible mainly because the Moon looks so large and dominant in the night sky while a country, even a huge one, feels earthbound and ordinary. But Australia is the sixth-largest country in the world by area, comparable in size to the contiguous United States, and its sheer east-to-west span is simply larger than most people intuitively expect a single country, or a celestial body overhead, to be.