Destruction of Mondas

The destruction of Mondas occurred when the planet returned to the solar system in an attempt to steal energy from its twin planet Earth. Having finally exhausted its own energy, Mondas disintegrated completely, the CyberMondans dying along with it. (TV: The Tenth Planet)

Most accounts dated the event to December 1986, as the arrival of Mondas was covered by media, (TV: The Tenth Planet, PROSE: Iceberg, AUDIO: The Reaping) although another count showed an older Ben Jackson and Polly Wright celebrated New Year's Eve while puzzled over the lack of coverage, Ben believing it was covered up. (PROSE: Mondas Passing) Two other accounts dated Mondas's arrival to the 1990s (PROSE: The Power of the Daleks) or the year 2000. (PROSE: Doctor Who and the Tenth Planet, Doctor Who and the Tomb of the Cybermen)

Later, CyberNeomorphs operating from Telos attempted to divert Halley's Comet to destroy Earth in 1985 and prevent Mondas's destruction. Gustave Lytton commented that Mondas being destroyed had "now become part" of the Web of Time, implying it wasn't initially. (TV: Attack of the Cybermen) As part of the Web, however, the Sixth Doctor reflected that saving Mondas could cause disastrous repercussions in every corner of the universe, killing billions, instantly disappearing major civilisations, and threatening the fabric of the universe itself. (PROSE: Attack of the Cybermen)