The bitter irony of idolatry is fully exposed in the tragic fate of its worshippers. Those who dedicated their lives to revering the stars and heavenly bodies will ultimately have their bones laid bare before those very same entities, receiving no salvation from them. During the siege of Jerusalem, the Chaldean invaders will overtake the graves of the leaders—tombs as magnificent as palaces—and violently cast their bones outside [רש"י]. This deliberate scattering of remains in the open sunlight is designed as an act of profound humiliation and disgrace [מצודת דוד]. The heavenly bodies looking down upon this scene are the exact stars and idols the people once served [מצודת ציון].
The intense devotion of the people of Judah to these false gods is reflected in their varied and persistent methods of worship [מצודת דוד, ביאור שטיינזלץ]. Their idolatry spanned different levels of commitment, ranging from deep emotional attachment to superficial gestures [מלבי"ם]. At the highest level, they loved the idols, fully accepting them as divine and attributing all life's abundance, goodness, and beauty to them. They also served them out of fear, offering sacrifices to appease their anger and ward off disaster. Beyond this, they actively sought out the idols to uncover the future and hidden mysteries, and they followed them by attempting to imitate their supposed traits and ways. At the very least, they bowed down, offering a basic, outward display of respect [מלבי"ם].
The severity of their punishment directly mirrors the depth of their sin. In a stark reversal of basic human dignity, they will suffer an absolute denial of burial. While the bones of prominent leaders are typically gathered into coffins of honor, these remains will not be gathered at all, nor will they receive even a simple burial [מצודת דוד, מלבי"ם]. The exhumation of the dead serves as a sweeping historical punishment for the severe sins committed by the living of that generation [רד"ק]. Left exposed on the surface of the earth for an extended period, the unburied bodies will simply rot, ultimately turning into manure scattered across the open fields [רש"י, רד"ק, מצודת ציון].