After finding these planets, as I’m sure you can guess, scientists used all sorts of instruments to study them. Now that scientists have confirmed the existence of nearly 1000 exoplanets and have more than 3000 planetary candidates. This definition of the habitable zone was defined about 20 years ago, a few years before any exoplanets had been found.

Naturally, Earth falls neatly within this range at an orbit of 1 AU. After a little bit of math, astronomers determined the Goldilocks zone to be between 0.95 AU and 1.67 AU (an AU is an Astronomical Unit, which is the average distance between the Earth and the Sun). We know how much energy the different types of stars produce, we also know how much energy and pressure it takes for water to be a liquid. If we see evidence of liquid water, the planet or moon becomes more exciting for it too may harbor life.įortunately, when you have a theory centered around liquid water, you can give some parameters to help filter out planets that are potentially habitable and planets that aren’t. This gives us a way to predict the habitability of planets or moons we find. Everywhere on Earth where we find water – underneath ancient arctic ice, at the bottom of the oceans, and even in the clouds – we find thriving life. Liquid water is necessary for our type of live to evolve.

This is the region of space around a star where conditions are ‘just right’ for liquid water to exist on the surface of a planet. For anyone mildly interested in exoplanets, you are familiar with the term ‘Goldilocks Zone’.

Goldilocks galaxy