Here's why:

* Plasma is the fourth state of matter. It's a superheated gas where electrons have been stripped from atoms, creating a mix of ions and free electrons. This makes plasma highly conductive and responsive to magnetic fields.

* The Sun's core is incredibly hot. Temperatures reach millions of degrees Celsius, enough to strip electrons from atoms and create a plasma.

* The Sun's immense gravity holds this plasma together, creating a stable and continuous fusion reaction.

So, the Sun isn't a giant ball of fire, but rather a massive ball of superheated plasma!