Australia is wider than the Moon.
Why it is true
The Australian continent is about 4,000 km wide, while the Moon has a diameter of approximately 3,475 km.
Source: Geography
Would you rather be asked first?
This is the reading side of the site, so the answer is in the sentence above — that is the whole point of it. Test yourself works the other way round: the question comes on its own, and the fact and the explanation only appear once you have answered.