Heaven may be religion's business, but the heavens -- the planets and stars -- are astronomy's.
Well, not quite.
Mankind's quest for God has always pointed to the heavens. It's no accident, then, that the path of faith led Muslim astronomers -- and, later, Christian Europeans -- to discover scientific truths behind the planets and the stars.
As the world marks the International Year of Astronomy, the historic links between religion and science, faith and reason, are worth nothing, says Guy Consolmagno, an acclaimed American astronomer. Of course, Consolmagno, after whom an asteroid is named, is also a Jesuit who does his research at the Vatican Observatory in the papal summer palace at Castelgandolfo, south of Rome.
"John starts the gospel, 'In the beginning was the Word.' Now, the word 'word' is actually the Greek 'logos' which is where we get the word 'logic' from," Consolmagno tells RFE/RL. "And to the Greek philosophers of that time, that word carried such a weight because it meant reason, it meant logic. And so the Gospel is saying, at the beginning was logic, was reason, were the laws of the universe. These were with God -- these were God."
As God was worth knowing, so began the quest for scientific truth, which from the earliest days fixed its gaze on the stars.
Ancient Persia, India, and Greece made the world's first astronomical breakthroughs. Ptolemy of Roman Egypt, who wrote in Greek, believed Earth was the center of the universe around which the sun, planets and stars revolved. His theory stood until the 16th century when Copernicus, a Pole, defied Roman Catholic teaching and put the sun at the center of the solar system amid a much vaster universe.
His theory was confirmed by Italian Galileo Galilei, called the "father of observational astronomy" because of improvements he made to the telescope. The Year of Astronomy, kicked off by the United Nations in Paris on January 15-16, is dedicated to the 400th anniversary of Galileo's first discoveries in 1609, which led to his imprisonment by the Vatican for heresy.
After Galileo, the Age of Reason and science would sweep Europe, leaving the rest of the world behind. But between Ptolemy and Galileo, a gap of some 1,500 years, was the "Golden Age" of Islamic astronomy, which first transformed the art of sky gazing into a pure science of the stars.
There is also growing evidence that Islamic astronomers, whose Arabic translations were often the only surviving texts of ancient Greek works including Ptolemy's, provided fundamental impetus to the European Renaissance and the scientific explosion that followed it.
The Koran itself invites believers to find guidance in the movement of the stars. It also insists, "the Universe is ruled by a single set of laws" -- which, like the Gospel of John, seems to put logic and reason behind creation.
The first Muslim astronomers studied the heavens to develop a new Islamic calendar, based on the need for months to begin when the crescent moon first appears. Called to pray five times a day, they were also compelled to find a mathematical way to fix Mecca's direction from any location.
From Baghdad to Samarkand, from Al-Andalus (southern Spain) to Istanbul, the list of great Islamic astronomers runs long and rich.
Among the most celebrated are Albetenius, who around the year 900 determined the solar year as being 365 days, five hours, 46 minutes and 24 seconds. Other greats include Ulugh Beg, the Turkic astronomer born in Persia who made key advances in trigonometry and star cataloguing, and in the 1400s established a school on Registan Square in Samarkand, now in Uzbekistan.
Lebanese-born George Saliba is a historian of Islamic science at Columbia University in New York. In his latest book, "Islamic Science and the Making of the European Renaissance," Saliba traces the links between the Islamic "Golden Age" of astronomy and the Age of Reason in Europe. In particular, he cites new evidence of Arabic science impacting the work of Copernicus.
Saliba says Muslims made astronomy into a science by focusing on empirical research and developing the mathematics to support it. That proved a huge advance, he says, on the ancient world, which saw the stars in a mythological sense -- as symbols of gods and deities.
"What Islam has done, what Islamic civilization has produced, is to say that astronomy is just like any other scientific discipline: It has to be consistent in explaining the physical phenomena around us with a mathematical language," Saliba tells RFE/RL. "Of crucial importance is the emphasis on the mathematical language, that the language should be consistent with the physics we are describing. This inner consistency of science is the single most important contribution that Islamic astronomy has made."
But where have all the great Islamic astronomers and scientists gone?
Some historians, such as Lebanon's Amin Maalouf, blame the decline of Islamic science since the 16th century on a lack of political freedom in the Muslim world relative to that enjoyed in Europe, even under the monarchies.
Saliba, however, says the whole world fell behind Europe, scientifically.
"The rest of the world began to look comparatively as if it went into decline," he says. "This does not only touch Islamic civilization. It touches the Indian, it touches the Chinese, and it touches actually the whole non-European world. So trying to answer this question by finding something wrong in the Koran, or something wrong in Islam misses the point, because it is not particular to Islam. It's a universal phenomenon that Europe began to take off and the rest of the world was left behind."
With Galileo the poster child of the Year of Astronomy, some point to his persecution by the Catholic Church as proof that religion and science can't co-exist. It wasn't until 1992 that Pope John Paul II apologized and rehabilitated Galileo.
But Consolmagno says many great scientific discoveries since Galileo were by Catholic clerics. Like the Big Bang theory, which George Lemaitre, a Belgian priest, first proposed in reaction to Albert Einstein's theory of relativity.
For the American Jesuit, trained at the Massachusetts Institute of Technology, the quest for truth is at the heart of faith and science. "Religion tells me who made the universe," Consolmagno says. "Science tells me how he did it."