Here is an AE as of Faustina I, posthumous, depicting her as Aeternitas, the personification of eternity, facing left, on a globe, which I assume is Earth. It has been rather dark and wet recently. Is she sitting on California? RIC 1159 10.92 grams
Thanks for this helpful post and thread, @GinoLR! I've certainly been confused about this subject! The Constantinian BEATA issue seems to have quite a variety of globe depictions. Mine seems to have one equatorial line and then two fairly widely spaced lines perpendicular to it - I guess modified by the engraver from the standard two perpendicular belts? (And what do the dots represent - land masses?)
I'm with @Victor_Clark on this one. The consensus of expert opinion seems to be that these coins depict the celestial sphere, not the earth.
A very interesting thread @GinoLR . I have nothing of substance to add to the question of celestial sphere vs earth but I have enjoyed the read. Here are a few relevant coins. Poking the unsuspecting earth with a stick? Roman Empire Severus Alexander AR Denarius, Antioch mint, struck ca. AD 222-235 Dia.: 18 mm Wt.: 3.35 g Obv.: IMP C AVR ALEXAND AVG; Laureate, draped and cuirassed bust right Rev.: PROVID DEORVM; Providentia standing left, holding wand over globe and sceptre Ref.: RIC 294 Ex arnoldoe Collection, Ex Otto Helbing Nachfolger 86, Lot 1585 (Nov. 25, 1942) This one is more of a glob than a globe. Or perhaps a deflated football? Deflate-gate AD 276. Roman Empire Probus, BI Antoninianus, Tripolis mint, second officina, struck ca. AD 276-282 Dia.: 22 mm Wt.: 3.82 g Obv: IMP C M AVR PROBVS P F AVG, radiate, draped and cuirassed bust right Rev: CLEMENTIA TEMP•, emperor standing right, holding eagle-tipped sceptre, receiving globe from Jupiter, holding sceptre, crescent in lower centre, KA in ex. Ref.: RIC V(b) 927. Ex Doug Smith Collection (illustrated on his webpage for Probus), acquired in 1997 from Kreuzer
Some images of ancient celestial globes might be helpful. "Farnese Atlas", 2nd century AD, celestial globe carried by Atlas. "Kugel Globe", 2nd-1st century AD.