In Avatar: The Last Airbender, firebenders receive insane bending power from Sozin’s Comet, even though comets are made of ice. Sozin’s Comet, which passes near the earth every hundred years, was named after Prince Zuko’s great-grandfather, Fire Lord Sozin. Shortly after Aang disappeared from the Southern Air Temple, Sozin used the power he gained from the comet to begin the Hundred Year War. Under Sozin’s reign, the Fire Nation wiped out the Air Nomads and nearly destroyed Katara and Sokka's home, the Southern Water Tribe. Sozin’s son, Azulon, and grandson, Ozai, continued Sozin’s legacy of violence, attempting to conquer the remaining nations. Fire Lord Ozai nearly succeeds in his mission with the help of Sozin’s Comet as it passes near the earth once again.

Avatar Roku warns Aang about the comet when Aang visits the Fire Temple in Avatar season 1, episode 8, “Winter Solstice: Part 2: Avatar Roku." Roku tells Aang that Sozin's Comet will return before the end of the summer, meaning Aang has less than a year to master all four elements or Ozai will destroy the world. As Roku forebodingly says, “Not even the Avatar will be able to restore balance.” Once Roku and Aang have finished talking, Roku destroys the temple, which is situated on a volcanic island. This is because firebenders gain strength from heat sources like volcanoes, the sun – and Sozin’s Comet, despite being made of rock and ice. However, there's a reasonable explanation for this.

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The reason that firebenders gain power from a comet largely made of ice is that it passes close enough to the atmosphere that it ignite, causing it to become a heat source that fuels the firebenders’ abilities. In the real world, there is a similar phenomenon called an 'Earth-grazing fireball,' though the term usually applies to meteorites. Regardless, anything that would pass close enough to Earth’s atmosphere to light up the sky like Sozin’s Comet would have its mass and velocity altered. So, even if the comet or meteorite were not completely obliterated by the atmosphere, its orbit would change, meaning that it would not pass near the planet with the same predictable frequency as a typical comet. But in the world of Avatar, astrophysics work a little differently and Sozin’s Comet becomes a flaming fireball every hundred years, visibly passing overhead and increasing the power of the firebenders.

Avatar Fire Lord Sozin and Roku in Avatar the Last Airbender

In Avatar, many other naturally occurring phenomena also influence the powers of different benders. During a lunar or solar eclipse, waterbenders and firebenders are at their weakest, respectively. Waterbenders also gain strength during a full moon. And the book Avatar: The Last Airbender: Legacy reveals that earthbenders are strongest in the spring and airbenders are strongest in the fall. Most of these increased power events occur simply because one element peaks during these times and, by effect, the benders of that element are also strengthened. However, the effect of Sozin’s Comet is described differently in The Last Airbender movie. In the epilogue of the film, Fire Lord Ozai tells his daughter Azula, “Sozin's Comet is returning in three years. It will give all firebenders the ability of the highest firebenders, the ability to use their own Chi to create fire.” This is different from the show, where firebenders can create their own fire - regardless of skill level - and Sozin’s Comet simply gives them an incredible boost in power.

In Avatar: The Last Airbender, Sozin’s Comet finally appears in the series finale. All three seasons slowly and constantly build to the climactic battle between Aang and Ozai as Sozin’s Comet passes overhead. Had Aang failed, Ozai would have been able to use the power of the comet to win the war that his grandfather started. Luckily, Aang has managed to master the elements throughout the course of the show and defeats Ozai by taking away his bending rather than killing him. After Ozai's defeat, the Hundred Year War is over, with Sozin’s Comet marking both its beginning and end.

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