The team behind NASA's Kepler space telescope has just announced the discovery of another very interesting new exoplanet. The newly named Kepler-452b would appear to be a planet slightly larger than our own Earth, that is orbiting a Sun-like star at just the right distance to be in the “habitable zone”. They are claiming that this new planet is the most Earth-like that has yet been discovered in the twenty years of exoplanet hunting.

In addition, the team also announced several other planets that are potentially habitable, just not identical to Earth. But life can occur anywhere, so they are all interesting. The habitable zone is a range of distances from the host star at which the planet is close enough to be warmed by the star, but not so close that it gets too hot for life. In our own Solar system, Mercury and Venus are too close to the Sun and therefore too hot for life, while the outer planets are icy cold (although some could support life through other means of energy production). But in general, life is expected to exist only where water remains in its liquid form, and that is a relatively narrow temperature range

At present, we know of about a dozen planets which are comparable in size to the Earth and which exist in the habitable zone of their parent star.

This newly discovered planet, Kepler-452b, is particularly interesting due to its size, location, and composition. It is about 50% larger in diameter than the Earth, and its parent star looks to be of similar age and composition to our own. Furthermore, based on its mass and size it is probably composed of rocks just like the Earth.

The previous candidate for “Earth-twin” as some of you may recall from an earlier article I wrote, was Kepler 186f located about 500 lightyears away from us. It is closer in size to the Earth, at only 10% greater diameter, but it orbits a red-dwarf star that is much smaller and cooler than our own Sun. The surface of Kepler-186f would only ever be about as bright as an Earth sunset.

For now though, Kepler-452b seems to be the best candidate yet for a life-supporting clone of the Earth. The technology needed to visit it is still far into the future, but for now we can gaze up at the stars and dream of what is out there...