The 8 Most Earth-Like Planets Scientists Have Discovered…So Far

No. 6: HD 40307 g

Photo Credit: ESO

Earth Similarity Index: 67%

Although opinions are still divided when it comes to HD 40307 g, some do believe that liquid water and a night and day cycle do exist on the planet. Astronomer R. Barnes, on the other hand, thinks that HD is more Neptun-like rather than Earth-like.