On July 23, 2015, NASA announced the discovery of a twin of Earth outside the solar system, named "Kepler-452b."
This planet was discovered by NASA's Kepler orbiting observatory, which was launched into space in 2009.
The planet "Kepler-452b" is located in the constellation Cygnus, which is 1,402 light-years away from the solar system.
What is believed to be a twin of Earth, was named after the space telescope that discovered it. This planet is one of the most similar to our own, making it an Earth 2.0, as it has been called, and one of the most likely planets to be a promising candidate for searching for forms of extraterrestrial life, in addition to the possibility of being habitable.
The Kepler space telescope was able to discover this Earth-like planet using the transit method, which is done by observing the change in the brightness of its parent star caused by the planet passing over its background.
Importantly, Kepler-452b is the first possible planet with a rocky Earth to be discovered, orbiting a star that is somewhat similar to the Sun in the spectral class G2, in the habitable zone suitable for life, which is determined by its distance from its parent star.
The habitable zone is a conditional area of life in space, determined on the basis of how similar the conditions on the surface of the planets are to those on Earth, and how likely it is that water can exist in a liquid state. Accordingly, such planets or their moons will be favorable for the emergence of life similar to life on Earth.
This planet, which is similar to Earth and about 60 percent larger, completes a full orbit around its star in about 385 Earth days. It is located in the same galaxy as ours, the Milky Way, and is about 1,480 light-years away from our solar system.
While the physical properties of the planet are difficult to study in detail, scientists assume that Kepler-452b is a rocky planet, five times heavier than Earth, and that the gravity on its surface is twice that of our planet.
It is noteworthy that this Earth's twin is 1.5 billion years older than our planet, and its expected lifespan will extend for about another 3.5 billion years.
The amount of light, or insolation, that reaches the planet from its parent star is 1.1 times greater than the sunlight on Earth. This measurement excludes possible global warming, while the average surface temperature of Kepler-452b is estimated to be about minus 8.15 degrees Celsius.
However, Kepler-452b is not the only candidate to be Earth 2. It is the sixth Earth-like planet on the list. According to the Earth Similarity Index (ESI), it ranks below the most distant planet, Kepler-438b, which has an Earth similarity score of 0.88 out of a maximum of 1.
Space discoveries, such as the geographical discoveries that began in the fifteenth century and ended with the colonization and exploitation of the wealth of what is known as the New World, may therefore appear in the future, the first human colonies outside planet Earth.
Searching for habitable planets outside the solar system is not an extra luxury that competing countries spend billions on, but rather a necessity that may become urgent at some point, especially if climate change worsens on our only planet.