History and specifics
Many thousands of years ago, the planet appeared predominantly blue when the entity Isis triggered the evolution of humanoid Isisians. It guided their development into a technologically advanced civilization, which eventually died out 25,000 years ago.
In 2267, the starship USS Enterprise arrived to study the star's final hours. James T. Kirk, Nyota Uhura, Christine Chapel and Spock visited Isis III to investigate a massive lifeform reading. Solar activity created dramatic views in the sky and disrupted tricorder readings. Kirk and Spock explored the ruins of an ancient city and reviewed their historical records.
The lifeform turned out to be a humanoid manifestation of the Isis entity. As the entity began to die, it was able to return the landing party and direct the starship to safety as the star went supernova and the planet exploded. (TOS comic: "Death of a Star")