What is Melancholia in the 2011 film of the same name by Lars Von Trier?

Explanation

Apocalyptic films have always been popular and many of the masters of film have tried their hands at the subject. As an example, in 2005, Steven Spielberg directed 'War of the Worlds' with Tom Cruise, where aliens come to harvest humans. In the film '2012' by the German director Roland Emmerich, the apocalyptic prophesy of the Mayans becomes true. A more artistic example is Lars Von Trier's 'Melancholia' from 2011 where the planet Melancholia swallows Earth.