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

A new view of the Whirlpool Galaxy, one of the two largest and sharpest images Hubble Space Telescope has ever taken, is released by NASA on Hubble's 15th anniversary April 25, 2005.Handout YH/NASA/Reuters

By Alice Milliken

New research has revealed that every solar system in the Milky Way has the same elemental building blocks as Earth, making the presence of Earth-like planets more three times more likely.

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 there are planets orbiting stars in the Milky Way that have the potential to be "a lot like Earth".

He claimed that solar systems are three times more likely to have an Earth-like planet than previously thought based on their elemental make-up.

The minerals which are 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, which dictates the weather and if the planet is hospitable. Too much of one or another element will produce environments unable to sustain life.

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 research, conducted with a team from E A Milne Centre for Astrophysics at the University of Hull, shows that every solar system has the same elemental building blocks as ours.

"At first, I thought we'd got the model wrong," Gibson explained 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 when we looked at planetary formation, every solar system we looked at had the same elemental building blocks as Earth."

The research team created a simulated model of the chemical evolution of the Milky Way. When comparing their results to previous research, which did not have the same access to technology to accurately identify chemical elements, Gibson and his team discovered that older findings were at fault.

Gibson said that after removing the outdated approaches to determining the chemical structures of planetary systems, which involved focusing on larger planets that orbit brighter stars and produced a 10-20% scientific uncertainty, "observations agreed with our predictions that the same elemental building blocks are found in every exoplanet system, wherever it is in the galaxy".

However, despite these updated findings, 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."


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