In our journey through the solar system, we've encountered the four innermost planets: Mercury, Venus, Earth, and Mars. These planets, often referred to as "terrestrial" due to their rocky compositions and solid surfaces, have a lot more in common - and differences - than one might initially think. The search for life beyond Earth often focuses on Mars. Evidence suggests that in the past, the surface environment of Mars had liquid water and may have been habitable for microorganisms, but habitable conditions do not necessarily indicate life. If previous life on Mars were confirmed, what implications would that have for current scientific knowledge? How might this discovery help humans learn more about past, present, or future of life here on Earth?