Scientists have devised a way to identify which galaxies in the Universe are most likely to be able to sustain life.
Edinburgh astrobiologists helped created a framework with which to scan all the galaxies in the nearby Universe, to pinpoint which types are most likely to host complex life.
This study allows us to start thinking about habitability on an extragalactic scale, and its distribution in the Universe.
Their method involves mathematical models, based on a set of physical properties that increase the likelihood of galaxies being able to support life.
Their calculations show that elliptical galaxies which are at least twice as massive as the Milky Way, but with a slower rate of forming stars, and whose atmospheres are rich in metal, can potentially host 10,000 times as many habitable earth-like planets as the Milky Way.
Up until now, estimating how habitable galaxies are across a range of physical properties has been challenging for scientists.
The emerging field of astrobiology has made significant progress in understanding the habitable zones around stars in which life can evolve into complex forms.
A few previous studies have developed the idea using computer models to simulate galactic-scale habitable zones for the Milky Way and some elliptical galaxies.
It is already known that three key criteria governing the likelihood of a galaxy being able to support life are intricately linked.
These are total mass in stars, total mass of metallic elements, and star formation rate.
Researchers say there may be as many as 100 billion planets in our own galaxy, the Milky Way.
However, it is unknown what fraction of these may be habitable, and we have yet to discover one that is indeed habitable.
This latest research is another step towards understanding habitability in our own galaxy and beyond.
The study, carried out with Durham University researchers, is published in Astrophysical Journal Letters.
Our approach is the beginnings of a method than can be applied to try and understand where best to search for habitable planets outside our own solar system.