exoplanet
Thousands of exoplanets could host life, models suggestNasa/JPL

Thousands of planets outside our solar system have the potential to host alien life following the discovery that they have day-night cycles like Earth.

Astrophysicists from the University of Toronto have found that contrary to previous thinking, exoplanets rotate around their stars.

Traditionally, scientists believed exoplanets always show the same side to their star because they rotate in sync with it. This means one side is always facing the star, while the other is plunged into perpetual cold and darkness.

Findings from the latest study suggest these planets are more Earth-like than once thought.

Lead author Jérémy Leconte said: "Planets with potential oceans could have a climate that is much more similar to Earth's than previously expected.

"If we are correct, there is no permanent, cold night side on exoplanets causing water to remain trapped in a gigantic ice sheet. Whether this new understanding of exoplanets' climate increases the ability of these planets to develop life remains an open question."

The study, published in Science Express, used 3D climate models developed to predict the effect of a planet's atmosphere on the speed of its rotation. "Atmosphere is a key factor affecting a planet's spin, the impact of which can be of enough significance to overcome synchronous rotation and put a planet in a day-night cycle," Leconte said.

Findings showed exoplanets are more likely to have liquid water and be habitable than we once thought.

While astronomers still need observational evidence, their findings show many exoplanets should be able to maintain an atmosphere as massive as that of Earth.

On our planet, most of the sun's light reaches the surface, producing a moderate climate across Earth. Having both day and night drives winds that redistribute the mass of the atmosphere.

However, the authors also note that although these exoplanets would have a day-night cycle, the duration of them could be vastly different, lasting anything from weeks to months.