In 1584, the philosopher Giordano Bruno speculated that the Universe might be full of planets just like our own. For daring leaps of the imagination such as this, the Church duly branded him a heretic, rewarding him with imprisonment and a fiery death at the stake.

Today, we went one step further to proving him right. At a press conference earlier today, astronomers announced the discovery of two planets the same size as the Earth. These are the smallest planets ever discovered outside our solar system and the first definitive proof that worlds on a similar scale as our own exist.

The planets, Kepler 20-e and Kepler 20-f, are very close to their parent star, and therefore too hot to bear any real similarity to our home world. The news comes hot on the heels of the discovery of a planet in the “habitable zone” around a star, where it is possible for water to exist in liquid form. We are now hot on the trail of a planet that meets all the basic criteria for supporting life.

The discovery comes via Kepler: a space telescope that is surveying thousands of stars in a small area of the sky, roughly in the region of the Summer Triangle. It records the light emitted from each of the stars over time, playing close attention to any slight dips in brightness. These dips may indicate a planet moving in front of the star and momentarily blocking its light. Kepler’s systematic approach has revolutionised the science of planet hunting. To date, with just over a year’s data processed, it has found over 1,200 candidate planets.

It is surely only a short time now before a small Earthlike planet is discovered that is just the right distance from it’s parent star to support life. Who knows what may be discovered in the future about these small, watery worlds? We live in hope.