Some scientific theories speculate that Earth analogs may have existed in our Solar System in the past. In the future, technology may be used by humans to artificially produce an Earth analog. In theory, terraforming, virtual reality or simulated reality could potentially create such a world. Multiverse theory suggests that an Earth analog could exist in another universe or even be another version of the Earth itself in a parallel universe. Continue reading to see more real Earth-like planets discovered by researchers.

Technological advances in extrasolar planet detection are rapidly refining the probabilities of a real discovery, not just in our universe, but in the present Milky Way galaxy, though distribution and attributes are still very much unknown. Different studies on the frequency of Earth-like planets in the Milky Way have resulted in estimation varying from one (i.e. the Earth) to billions. Current calculations tend to indicate that they may be relatively common in the universe.

The more recent serious scientific findings have greatly influenced the scope of the fields of astrobiology, models of planetary habitability and Search for Extraterrestrial Intelligence. NASA and the SETI Institute have proposed categorising the increasing number of Earth-like planets found using a measure called the Earth Similarity Index (ESI) based on mass, radius and temperature. According to this measure, the planet currently thought to be most similar to Earth is Gliese 667C c (0.85).