Puxatornee

Puxatornee was a planet placed under the protection of the Galactic Heritage. (PROSE: The Tomorrow Windows) The Doctor had visited the planet in 3012 and then again in his seventh incarnation with Mel Bush in 3090, while in search of leptonite crystals to defeat the Quarks. The Doctor and Mel, however, visited in two separate intersecting alternative timelines, centering around the fate of President Bailey in 3060 and the fate of Puxatornee itself in 3090. (AUDIO: Flip-Flop)

In both timelines, on December 24th, 3060, the Slithergee race arrived at Puxatornee and requested to be allowed to settle on the first moon. Bailey knew this was an important decision, and sent her husband, Deputy Mitchell home, while she thought it over. But, once he left, she engaged in her secret affair with her secretary, Clarence.

Slithergee Timeline: The interference of the Doctor, Mel, Lieutenant Stewart, and Lieutenant Reed, from the war timeline, resulted in Clarence being shot dead, as according to the lieutenants, he was going to assassinate Bailey. The Doctor is unable to bring himself to shoot Bailey to prevent the timeline from being changed. The two lieutenants explain who they are to Bailey and that she should make peace with the Slithergees to prevent a devastating war. With security closing in, the four departed, leaving Bailey, still distraught over Clarence, to order for the Slithergees to be given whatever they want.

Thirty years later, thanks to Bailey constantly giving in to them, the Slithergees had since moved from the moon to the actual planet, where they had integrated themselves into the colony, getting humans to serve them as sight guides. Some people had rebelled, becoming terrorists fighting against Slithergee oppression, including this history's version of Stewart and Reed. Some confusion occurred on December 24th and December 25th, with the presence of two versions of the Doctor, Mel, Stewart, and Reed. By the end of the 24th, the two lieutenants were killed, and the war timeline Doctor and Mel had escaped in the TARDIS, seconds before the arrival of the Slithergee timeline Doctor and Mel. By the end of December 25th, the terrorists Stewart and Reed have forced the Doctor and Mel to take them back in time to 3060. Bailey was assassinated by Mitchell, who was then assassinated by the Slithergee Community Leader. As such, in this timeline, Puxatornee fell completely under the control of the Slithergees.

War Timeline: The interference of the Doctor, Mel, Stewart, and Reed, from the Slithergee timeline, resulted in both Clarence and Bailey killed. Stewart planted his gun on Clarence to implicate him for the murder, and the four departed. Mitchell, distraught over the death of Bailey and refusing to accept she had been cheating on him, convinced himself that Clarence was a Slithergee agent and that they should declare war on the Slithergees.

Thirty years later, the planet was devastated by the war. In this history, Stewart and Reed joined the military and were now lieutenants. President Mitchell had a plan, though. He has Professor Capra construct a time machine, so that they can travel back and prevent Bailey's assassination and avert the war. Some confusion occurred on December 24th and December 25th, with the presence of two versions of the Doctor, Mel, Stewart, and Reed. By the end of December 24th, the Slithergee timeline Doctor and Mel had escaped in the TARDIS, seconds before the arrival of the war timeline Doctor and Mel. By the end of December 25th, the terrorist versions of Stewart and Reed had been killed. The time machine was activated, sending Mel and Lieutenant Stewart back in time, with the Doctor and Lieutenant Reed following in the TARDIS. However, the time machine had a power supply issue that Capra had been unable to fix, before it was activated. The machine exploded, destroying the entire planet. As such, in this timeline, Puxatornee had no future, and was nothing but debris and dust.

Behind the scenes
The name of the planet references the (real) town of Punxsutawney, Pennsylvania, the setting of the oft-referenced comedy Groundhog Day, which stars Bill Murray as a character stuck in a time loop. Flip-Flop involves two intersecting time loops.