The Lord has called on his exiled people to not live in fear because of what is happening in Babylon (Jeremiah 51:46). Despite the upheaval and unrest in Babylon, the Lord is in control. Therefore, behold, the days are coming when I will punish the images of Babylon; her whole land shall be put to shame, and all her slain shall be put to shame.
There is more going on than just the political downfall of Babylon. The Lord is about to defeat her gods, the images of Babylon.
The Lord will overthrow the powers of evil.1 Then the heavens and the earth, and all that is in them, shall sing for joy over Babylon.
The whole cosmos will rejoice at the fall of Babylon because Babylon has stood against the Lord, the creator of heaven and earth and all that is in them. In a more immediate and historical sense Babylon must fall for the slain of Israel, just as for Babylon have fallen the slain of all the earth.
Judgment is coming to Babylon, not just because she has mistreated the people of Israel, but also because she has mistreated all the other nations. All of creation belongs to the Lord and he will punish and overcome all evil that is done everywhere.
48 Then the heavens and the earth, and all that is in them, shall sing for joy over Babylon, for the destroyers shall come against them out of the north,declares the LORD.