I believe the answer should be solar
Most of it follows its cycle, going back to the atmosphere.
The image below, shows you how the nitrogen cycle is.
Hope it helped,
Happy homework/ study/ exam!
Stars begin to form from clouds of gas in space. The cold temperatures and high densities (compared to elsewhere in space, but would be considered a vacuum on Earth) of these clouds allow gravity to overcome thermal pressure and start the gravitational collapse that will form a star.