Nasa has discovered a new solar system, where life could exist on three separate planets

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Three of the newly discovered planets could feature little green men. (Source: Getty)

The boffins at Nasa have discovered three habitable planets in a newly discovered solar system a mere 39 light years away from Earth.

In an announcement today, astronomers said they had found seven planets, all roughly the same size as Earth, orbiting a dwarf star, catchily named TRAPPIST-ONE.

The six planets closest to the star all lie in the so-called Goldilocks zone, in which temperatures are neither too cold nor too hot.

And three of those worlds are thought to be capable to having oceans.

"I think that we've made a crucial step towards finding if there is life out there," University of Cambridge astronomer Amaury Triaud told reporters on a conference call on Tuesday.

The discovery, published in this week's issue of the journal Nature, builds on previous research showing three planets circling TRAPPIST-ONE. They are among more than 3,500 planets discovered beyond the solar system, or exoplanets.

Researchers have focused on finding Earth-sized rocky planets with the right temperatures so that water, if any exists, would be liquid, a condition believed to be necessary for life.

The diameter of TRAPPIST-ONE is about 8 per cent of the sun's size. That makes its Earth-sized planets appear large as they parade past.

Tags: Nasa