There’s no place quite like home.

By Adam Smith

Astronomers operating NASA’s Kepler Space Telescope have spotted the most Earth-like planet found to date, around 500 light years across the galaxy from our Earth. Kepler-186f, a rocky planet which is about the same size as our home planet, is the latest in a ream of discoveries to spark excitement in the sky-gazing community for its potential to hold liquid water, and possibly even life.

The search for ‘exoplanets’, those outside of our own solar system, has been a major pre-occupation for astronomers in recent years, and a successful one to boot. Over 3,500 have already been detected, with just over 100 existing within the ‘habitable zone‘ around their star; where temperatures are safe enough to allow water to stay in liquid form and not be frozen solid, or boiled into vapour.

Scientists working with NASA’s Kepler Space Telescope estimate that around 22% of the stars like our Sun in the galaxy could host an Earth-like planet, and with the right conditions to hold life. Kepler-186f is an exciting discovery in particular, as it is the first exoplanet with a size similar to Earth’s to be discovered within the habitable zone.


Astronomers use a number of methods to detect exoplanets. One preferred technique is the transit method; where an exoplanet moves in front of its parent star’s disk, which dims the light which we see from the star. This is similar to an eclipse which we view from Earth, but as it occurs so far away, requires very precise telescopes and equipment to measure the tiny variations in light.

Astronomers can use the amount of ‘dimming’ to work out the size and structure of the star, whether it is a rocky planet like ours, or gas-based like Jupiter or Saturn. This was the method used to detect Kepler-186f.

So how likely are we to find life on Kepler-186f?

In truth, we can’t be sure. We do know that its size and position around its star mean that it’s certainly possible that liquid water, the key to life, could be found there.

In astronomical terms, Kepler-186f is just a stone’s throw away, at 500 light years. By comparison, the centre of our galaxy, the Milky Way, is over 30,000 light years away. With a few breakthroughs in space travel, perhaps one day we’ll be able to take a look for ourselves.