11.2 billion-year-old star orbited by five earth-sized planets

Planet-hunting astronomers have found a star orbited by no fewer than five earth-sized planets. The find is even more unusual however because this distant sun is extremely old.

The star is 11.2 billion years old, formed just 2.6 billion years after the Big Bang that formed the universe and space-time. This likely occurred about 13.8 billion years ago, the astronomers say.

This means that life has had a chance to take hold in the universe for at least 11.2 billion years .

Earth-sized planets have formed throughout most of the universe's history, the authors write in their research paper published today Tuesday afternoon in the Astrophysical Journal. And this "opens up the possibility for the existence of ancient life in the galaxy", the authors write.

The research involved collaborators from the University of Birmingham and Iowa State University Ames and they were using data from the Kepler spacecraft run by the US National Aeronautics and Space Administration.

Kepler is a space telescope launched in 2009 with the specific aim of finding extrasolar planets orbiting distant starts. It has been spectacularly successful, finding more than 1,000 planets but it is partially disabled and normal observations have been suspended.

The researchers made their find, Kepler-444, when sifting through four years of data collected by the satellite. The star is smaller than our sun and the five rocky planets are way too close to their star to support life. All are on the hot side of the “Goldilocks zone” where a moderate temperature would allow liquid water to exist.

But the find tells the scientists that rocky planets formed from the early days of the universe and this means the opportunities for life to form on other planets have also been there a long time.

Scientists estimate our Milky Way galaxy could harbour 11 billion earth-like planets orbiting around sun-like stars.