On 01-15-2009, UNESCO inaugurated The International Year of Astronomy in Paris to commemorate the 400th anniversary of
the day Italian scientist Galileo Galilei (1564-1642) used a telescope to study the universe for the first time
(in 1609). On this occasion, we will relate some interesting stories about astronomy in the 17th century, from Europe
to Đại Việt ("Greater Vietnam")..
It was the time when the scientific revolution, in mathematic, physics, astronomy, anatomy and botany, etc took shape
and developed rapidly in Europe..
In astronomy, until then it was accepted that the sun was moving around the earth which stayed still, according to
Aristotle's (634-322 BC) and Ptolemy's (90-160?) theories, and in accordance with teaching of the Bible (for example,
Joshua blew his ram horn [shofar] to stop the movement of the sun when he destroyed the city of Jericho.) This is
geocentrism holding that the Earth is the center of the universe.
But in the 16th century, a monk, Mikolaj Kopernick (Nicolas Copernicus, 1473-1543) proposed another theory to the
effect that the earth was moving around the sun in his De Revolutionibus Orbium Coelestium (1543, shortly before his
death, but the work was completed approximately 30 years earlier). This is heliocentrism, or Copernican theory, later
confirmed by German mathematician Johannes Kepler (1571-1630) who announced what is known now as Kepler's Laws of
Planetary Motion. In the meantime, Galileo used a telescope, secretly applying the Kepler's laws and discovered many
celestial events: "the sub-lunar and super-lunar worlds" (les mondes sublunaires et supra lunaires), three small
planets next to Jupiter, the spots on the Sun, Venus, etc...