People in Australia See the Moon Upside Down

Why is the Moon so different from Australia?

Because we are on a spherical globe. My head is pointed in the opposite direction if I stand at the North Pole with my head up and a friend stands at the South Pole with their head down. When we look at the Moon together, I see a Moon with a dark Mare running along its “top” and a brighter region at its bottom. If you look at the South Pole from the opposite direction, the Mare will run along the Moon’s bottom edge. The brighter area will extend across the top. If I could move between the North & South poles, the Moon would appear to rotate in space, and my view of “up” would change with the Earth’s curvature. To replicate the South Pole friend’s view of the sky from the North Pole, I would do a perfect handstand and mimic manually the Earth’s curve. This method of replicating South Pole view is not perfect. Things that are directly above me at the South Pole are blocked by the bulky Earth.

A less extreme example is a person living at 45° North of Equator (which is exactly halfway between the North Pole (the Equator)) and someone who lives at 45° South of Equator (which is halfway between the South Pole (the Equator), respectively) each have their heads pointed “up”, but at 90 degrees relative. Their North/South separation still represents an up/down shift, so if they could swap places, they would say that the Moon has rotated by approximately 90 degrees. This is exactly the same perspective shift that my friend and me have when we look outward at the North and South poles.

This is why the Moon is the most prominent example in the night sky. However, it’s not only because it’s so familiar, but also because it may look odd in the Southern view if you are used to seeing it from the Northern perspective. The same thing happens with constellations. Orion, which is one of the most prominent and easy-to-spot constellations within the Northern winter sky, can be seen from both the Northern and Southern hemispheres. Orion’s appearance is similar to the Moon’s shift, with his head facing the ground and the rest of the stars above.