What is the etymology of the phrase "down under" when referring to things Australian? ~

Its below me to even contemplate to begin answering this question....for a start....I have no idea what yore on about....:( 

I wouldn't describe it as an etymology.

Rather, the phrase reflects the power balance between northern and southern hemispheres.

Europe and America (ie the West) collectively represent the most dominant economic, political and military power on the planet - with China, India, Russia and the Middle-East falling not too far behind - all north of the equator.

South of the equator, the countries of South America and Africa are still far behind in matters of influence - primarily due to factors of history.
Australia ranks as a middle power - having only moderate influence, but the only power of any significance south of the equator.
Even this much is only because of how we have welcomed America to position its radio-telescopes, satellites and naval ports on our territory to make up that crucial third of its global surveillance.
That makes Australia the Down Under country with respect to northern powers and perceptions.

If you ever travel here, you might be surprised to discover that you feel right-side up. ;) This post was edited by inky at September 10, 2019 6:13 AM MDT

That's easy.  The Rainforest (what's left of it) is the lungs of the  Earth.

Down under is the vagina.  

It refer two you're B'its and peices down under world wide I would think...
My god you've lived a sheltered life.....
This is a question you should be asking yore mummy .......hehe 

When you look at a globe or a map, Australia is down at the bottom.  Ergo, "down under" the other countries.  How's that for a short answer?

On a Eurocentric globe or flat map, cardinal North faces the top. Ergo, Australia is "under" most others. The term has been in use since the mid-19th century, and was given momentum by the chunder from down under, Men At Work, and their anthemic homage to Vegemite sandwiches.