Mars

Mars is a planet in the Sol System, which is most like Earth. It was extensively explored by humans who searched for Martian life.

History
Mars was explored by many unmanned rovers in the early 21st century, because it provided conditions which were hostile to humans. Eventually, humans landed, planted plants which released oxygen by photosynthesis with carbon dioxide. This made the Martian atmosphere a bit warmer. Eventually, oceans formed inside the huge basins, which covered half the planet and humans arrived and built colonies.

Physical characteristics
Mars is a small terrestrial planet, located 1.52 astronomical units (227.9 million kilometers) from Sol. After being terraformed by humans, its average surface temperature is 278 K (5oC), compared to just over 210 K before 2502.