Really cool particle effects. They made the sun look spectacular and bright, and the particle effects coming off the asteroids looked good too.
The health pickups were a nice addition as well. I definitely needed a few lol. I also liked how the theme revolved around shrinking the sun. It had a natural effect on the difficulty scaling too, since the sun became harder to hit as it got closer to being destroyed.
Nice work, the sun shrinking gave the fight a clear sense of progression and made the theme feel built into the goal.