Comparing the Sun and Earth

Comparing the Sun and Earth, both are astronomical objects, but one is a star and the other is a planet. Stars like the Sun are balls of ionized gas, called plasma, engaged in thermonuclear fusion. Gas giant planets are balls of mostly gas that aren't massive enough to ignite for fusion. Terrestrial planets like the Earth are balls of mostly solid and liquid that aren't massive enough to hold enormous atmospheres of gas. In the Sun-Earth relationship within the Solar System, the Earth orbits around the Sun.

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