SINCE 2009, NASA has been using the Kepler space observatory to survey our region of the Milky Way in the hope of finding an Earth-like planet suitable for humans.

And the space agency has had some luck with its search — most notably the recent discovery of Earth’s bigger, older cousin, Kepler 452.

However, a theoretical study from the Space Telescope Science Institute (STScI) in Baltimore suggests we may be wasting our time as most Earth-like worlds are yet to be born.

An assessment of data collected by NASA’s Hubble Space Telescope and Kepler space observatory revealed only eight per cent of the potentially habitable planets that will ever form in the universe have existed since the inception of our solar system some 4.6 billion years ago.

Co-Author of the study Peter Behroozi said he expects the remainder of the planets to form until the sun burns out in 6 billion years.

“Our main motivation was understanding the Earth’s place in the context of the rest of the universe,” he said in a statement released by NASA.

“Compared to all the planets that will ever form in the universe, the Earth is actually quite early.”

With data from the Hubble Space Telescope giving astronomers a “family album” of galaxy observations, they have been able to determine the universe was creating stars very quickly 10 billion years ago.

Co-author Molly Peeples said while this process has since slowed, there is still so much hydrogen and helium gas in the universe to ensure new stars and planets will be made for a very long time.

“There is enough remaining material [after the big bang] to produce even more planets in the future, in the Milky Way and beyond,” she said.

However, the researchers add future Earth-like planets are more likely to appear inside giant galaxy clusters and dwarf galaxies because there is a much larger supply of gas required to create stars and accompanying planetary systems.

The findings were published in the October 20 Monthly Notices of the Royal Astronomical Society.