The day when the heaven will become like molten silver.
The day will come when the sky will be like molten rocks.
On that Day the heaven shall become like molten copper
The day when the heaven is as molten brass
A day/time the sky/space becomes as the dead's puss/melted metal
When the end comes, the sky will look like melted copper
The day when the sky will be like molten silver
The day when the heaven will become like molten copper
On that Day the sky will become like molten copper
The day (it befalls), the heaven shall become (red) like molten copper
The Day that the sky will be like the boiling filth of oil, (or molten copper or silver or lead, etc.)