All through this whole ghost fleet thing I've had this question as to how a large ship in the sea can possibly keep its movements secret. Large media organisations seem to be unable to say where large tankers have been if they turn their transponders off.

Don't we have constellations of satellites constantly imaging the entire earth, both with visual and synthetic aperture radar, with many offering their data freely to the public? Wouldn't a large ship on the ocean stick out somewhat? And yet journalists seem lost without vesselfinder. Is this harder than I'm imagining, or are they just not paying the right orgs for the info?