30. It is much, much farther away from the sun than Earth.
Earth is about 93 million miles away from the sun. However, that number changes depending on the orbit the Earth is experiencing at that given moment. Most of the planets have elliptical rather than circular orbits, and the Earth is closer to the sun in winter than in the summer. Being much farther from the sun, Mars is much colder than Earth. However, scientists believe it is not too cold for life.
Mars is an average of 142 million miles away from the sun, placing it just outside of what scientists call “the Goldilocks zone.” If you remember the story of Goldilocks and the Three Bears, you recall that one bowl of porridge was too hot, one was too cold, and one was just right. The Goldilocks zone refers to the area around a star where a planet is not too hot, not too cold, but “just right” for life to thrive.