THE FIVE CEN­TRE POINTS OF AUS­TRALIA

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CEN­TRE OF GRAV­ITY METHOD

De­ter­mined us­ing 50,000 equally-weighted points around the main­land Aus­tralian bor­der, then cal­cu­lat­ing the point at which that hy­po­thet­i­cal cutout would bal­ance per­fectly.

LAM­BERT CEN­TRE

Oth­er­wise known as the grav­i­ta­tional cen­tre of Aus­tralia. It uses sim­i­lar method­ol­ogy to the cen­tre of grav­ity method, but based on the high-tide mark of 24,500 points around the main­land.

FAR­THEST POINT FROM THE COAST­LINE

The cen­tre of the largest cir­cle that can be drawn in Aus­tralia.

ME­DIAN POINT

The in­ter­sec­tion of the mid­point of the lon­gi­tude and lat­i­tude ex­tremes of the coun­try.

JOHN­STON GEODETIC STA­TION

De­fined in 1965 and set up in 1966, the trigono­met­ric sur­vey lo­ca­tion was set up by the Divi­sion of Na­tional Map­ping as the cen­tral ref­er­ence point. Mod­ern tech­nol­ogy, in­clud­ing GPS map­ping, has seen mod­ern sur­veys shift to the more ac­cu­rate Geo­cen­tric Da­tum of Aus­tralia, a mov­ing tar­get that ac­counts for small move­ments in tec­tonic plates.

CEN­TRE PUNCH

Five thou­sand kilo­me­tres gives you plenty of time to think, es­pe­cially when ev­ery sec­ond head­line has some­thing to do with Don­ald Trump, global warm­ing or ris­ing sea lev­els – or a com­bi­na­tion of the three.

This got us think­ing about the meth­ods used to cal­cu­late the cen­tre of the coun­try.

Even a small rise in sea lev­els could have a large im­pact on what is con­sid­ered the cen­tre of Aus­tralia. Larger tides in the north, for ex­am­ple, com­bined with shal­low ti­dal flats, like those seen at Broome, could eas­ily change the de­fined point of where the coast­line starts by many me­tres, in turn re­quir­ing a re­cal­cu­la­tion of ex­actly where the cen­tre is. All of which is for an­other day.

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