Answer:
Earth is similar to Venus, according to most people. It has a similar radius and diameter. It's also theorized that Venus is a runaway greenhouse effect, considering the temperature is so hot. This is due to the fact that the sun was alot smaller in the beginning of the solar system, and the habitable zone was where Venus was at. As the sun got older and bigger, the zone was pushed farther back to Earth.
Mars is similar in many ways. Its temperature is -80 degrees on average, which is pretty close compared to the other planets in our solar system. It has polar ice caps and noticeable seasons too. Life is certainly possible on Mars, as -80 is liveable.
