Jesuit priest José Gabriel Funes, director of the Vatican's astronomic observatory, says star-gazing brings him closer to God.

"I became an astronomer in order to get closer to God who created the universe," said Fr Funes at the observatory in the vast park surrounding the Pope's summer residence in Castel Gandolfo, near Rome.

"We wonder the same things that our secular colleagues do - how does the universe work, how did it originate, are there planets similar to earth?" said Fr Funes, 47.

Both Fr Funes and his colleague Guy Consolmagno studied astronomy before joining the priesthood.

"I'm primarily a scientist," said Fr Consolmagno, previously a university professor in the US.

"It's my belief in God that gives me the courage to do science because I have to have a faith... that there are answers, that there are laws to be found, that the universe is worth studying, it's not just chaos," he said.

"Where I actually experience God is in the joy, in the delight when the numbers suddenly make sense, when the theory works," he added.

The observatory Fr Funes has run since 2006 is housed in a former monastery on the edge of the papal sprawl, a fitting location suggesting the intersection of faith and science.

"But we are the pope's observatory. We are here to serve the pope, the Church and our colleagues," Fr Funes said, adding: "The Church has always been interested in astronomy."

Centuries ago, papal astronomers combatted theories seen as dangerous - such as those of Galileo Galilei, who had the temerity to claim that the earth revolves around the sun.

But all that seems far away here, where the second edition of Galileo's Dialogue Concerning the Two Chief World Systems - banned by the Inquisition in 1633 - is displayed with pride.