Earth-like planets 'three times more likely' in Milky Way than previously thought

Updated | New research has revealed that the elemental building blocks required to make Earth minerals are ubiquitious throughout the Milky Way, making the presence of Earth-like planets three times more likely than was previously believed.

Professor Brad Gibson from the University of Hull in the UK, presented the research at the National Astronomy Meeting in Llandudno on Wednesday,  telling the gathered audience that every solar system has the same elemental building blocks as ours.

Prior to Gibson's research, scientists grouped planets into three categories: those richer in carbon, those with more magnesium and silicon, and those similar to Earth. The latest study, conducted with a team from E A Milne Centre for Astrophysics at the University of Hull, found that the minerals responsible for the landscapes of the planets in our solar system, and other systems where planets orbit stars, are made up of four elements: silicon, magnesium, carbon and oxygen. The exact ratio of these elements to one another, and the amount of pressure in a planet's atmosphere, determines the land masses and the heating and cooling of the planet's surface. That, in turn, dictates the weather and if the planet is hospitable to organic life.

Our own solar system exemplifies how not all planets with these building blocks have the potential to sustain life. "We only need to look to Mars and Venus to see how differently terrestrial planets can evolve," Gibson concluded. "However, if the building blocks are there, then it's more likely that you will get Earth-like planets – and three times more likely than we'd previously thought."

These discoveries came out of a simulation that Gibson's team designed in order to better understand the chemical evolution of the Milky Way. After they first ran the simulation, they were suprised to find the results did not match up with previous models.

"At first, I thought we'd got the model wrong," Gibson said at the conference. "As an overall representation of the Milky Way, everything was pretty much perfect. Everything was in the right place; the rates of stars forming and stars dying, individual elements and isotopes all matched observations of what the Milky Way is really like." But once they looked closely, they realized that the older findings had missed some key pieces of information. For one thing, previous attempts to figure out the chemical makeup of planetary systems looked only at large planets orbiting very bright stars, which the new study says can lead to uncertainties of 10 to 20%. In addition, they say, previous research teams did not have access to the technology needed to accurately identify the spectra of oxygen and nickel.

Update: This article was edited for clarity.