Σελήνη/Selene (the ancient name) is Luna: our moon. Lowercase φεγγάρι/feggari/fengari is moon: you would say «δίδυμα φεγγάρια του Άρη» for “Mars' twin moons”.¹

Σελήνη/Selene (the ancient name) is Luna: our moon. Lowercase φεγγάρι/feggari/fengari is moon: you would say «δίδυμα φεγγάρια του Άρη» for “Mars' twin moons”.¹ In the same vein, capitalized Ήλιος/Helios is Sol: our sun. Lowercase ήλιος means any sun. ¹ Trivia: “satellite” is «δορυφόρος» = spear bearer; from the protectors of kings or powerful men in general, who typically encircled their protectees.