The recent discovery of an Earth twin has boosted chances there is intelligent life on other planets. But while Pope Francis's telescope scans the starlit skies, the Vatican is sceptical of ever meeting Mr. Spock.

On a leafy hilltop near the papal summer home of Castel Gandolfo sits the Vatican's Observatory, one of the oldest astronomical research institutions in the world, where planetary scientists mix the study of meteorites and the Big Bang theory with theology.

Boasting a prestigious research centre at the University of Arizona in the United States, the institute has never shied away from asking whether there could be life on other planets and is thrilled with the discovery of an "Earth 2.0".

Astronomers hunting for a planet like ours announced to huge excitement last week that they have found the closest match yet, Kepler 452b, which is circling its star at the same distance as our home orbits the Sun.

Around 60 percent larger than Earth, it sits squarely in the Goldilocks zone of its star, where life could exist because it is neither too hot nor too cold to support liquid water, according to the US space agency NASA.

The discovery "is great news", the Observatory's Argentine director Jose Funes told AFP, despite the fact that scientists suspect increasing energy from the planet's ageing sun might now be heating the surface and evaporating any oceans, making life difficult.

However, while "it is probable there was life and perhaps a form of intelligent life... I don't think we'll ever meet a Mr. Spock", he said.

The problem is that Kepler 452b is 1,400 light-years away -- an impossible distance to cover using mankind's current technology.

- No Jesus 2.0 -

NASA may have made history this year with a Pluto fly-by, but it took nine years for its probe to get there despite the planet being under six light hours away. The fastest spaceship in the Solar System, it would take some 11 million years to reach the Earth's cousin.

Funes, who has a degree in theology and doctorate in astronomy, would not be drawn on whether the Vatican would send out space missionaries to convert alien life-forms to Christianity if extra-terrestrial life was found elsewhere.

What is clear, he says, is that while God may have created aliens and planets similar to Earth, there can be no second Jesus.

"The discovery of intelligent life does not mean there's another Jesus," he insisted, because "the incarnation of the son of God is a unique event in the history of humanity, of the Universe".

Neat in his black cassock and surrounded by the latest astrological publications, Funes, 52, says science and religion co-exist perfectly together, insisting "if there was intelligent life (on another planet), I don't see that as a contradiction with the Christian faith".

"The bible is not a scientific book. If we look for scientific responses to our questions in the bible, we are making a mistake," he said.

"It answers great questions, like 'what is our role in the Universe?'" But such answers can also come from exploring the stars, he said.

"This type of research, the search for life in the Universe, helps us to understand ourselves... to understand our potential, but also our limits".