Nasa has discovered a “bonanza of new worlds” using its Kepler deep space observatory, almost doubling the number of known planets in the universe.
Most of the 715 newly confirmed “exoplanets” — worlds outside our solar system — are smaller than Neptune, which is four times the size of Earth. Four orbit in their sun’s habitable zone, where life-giving water may exist in liquid form.
The revelation raises the tally of confirmed alien worlds to nearly 1,700 since the first was identified almost two decades ago. “We’ve almost doubled, just today, the number of planets known to humanity,” said Dr Jack Lissauer of Nasa’s Ames Research Centre in California.
Following its launch in 2009, the Kepler probe made observations of 150,000 stars to seek out clues to the existence of planets among them. Only now, through the adoption of a new statistical technique for interpreting that data, have scientists been able to declare planetary discoveries.
Of the four “habitable-zone” planets, one orbits a star that is half the size of our Sun and only 5 per cent as bright. Another, twice the size of Earth, could be either a gas planet or a water world covered by a deep ocean.