The terrestrial planets are Mercury, Venus, Earth, and Mars.
Here's the explanation in regards to the Goldilocks Theory.
The Goldilocks Theory is often used by astrologists to describe the conditions of Earth's positioning in the solar system. The Goldilocks Zone was described by Stephen Hawking as "like Goldilocks, the development of intelligent life requires that planetary temperatures be ‘just right’” The Goldilocks theory argues that a planet must be neither too far away from nor too close to a star and galactic center to support life, while either extreme would result in a planet incapable of supporting life. Terrestrial planets such as Mercury, Venus, Earth, and Mars are more likely to lie in the Goldilocks zone due to their close proximity to their home star along with other crucial factors that allow for life to exist.
