* El sol no es rigel: Rigel is a star in the constellation Orion. It's a massive blue supergiant, much larger and hotter than our Sun. It's not in our solar system.

* The Sun is the biggest star in our solar system: ¡Esto es cierto! Our solar system is centered around the Sun, and it's the only star in it. All the planets, asteroids, and comets orbit the Sun.

* You can't see other stars as big as the Sun at night: While there are stars much larger than our Sun in the universe, we don't see them as big as the Sun because they are incredibly far away. The stars we see at night are so distant that they appear as tiny points of light, even if they're enormous.

En resumen:

* The Sun is the biggest star in our solar system.

* Rigel is a different star, much larger than our Sun, but it's not in our solar system.

* While there are larger stars in the universe, we can't see them as big as the Sun because of their immense distance.