Title: Europa 2009-International Year of Astronomy
Date of Issue: 12 June 2009
Country: Norway
Denominations: NOK 10.00 – NOK 12.00
In 2009, it is 400 years since Galileo Galilei (1564-1642) pointed a telescope at the sky and saw that the Earth was only one of many planets and not the centre of the universe.
His observation was the start of a revolution which changed Man’s
perception of the world  for ever. The United Nations has proclaimed
2009 the International Year of Astronomy and astronomy is also the theme

of this year’s  Europa stamps. The word astronomy comes from Greekand means the  science of celestial bodies. However astronomy is more than that.It  also combines other sciences and uses them to study everything that is to be found outside our own planet. Astronomy is thus the most comprehensive of all sciences.The Greek philosopher Aristoteles (384-322 BC) believed that the
Earth was the centre of the universe and that all the celestial
bodies circled round it. Aristoteles was highly respected and his
ideas were quickly accepted. Many hundreds of years were to pass
before anyone was able to challenge Aristoteles’ geocentric theory.
Towards the end of the Middle Ages more and more importance was being
attached to accurate scientific observation in astronomy. Nicolaus
Copernicus (1473-1543) was the first to understand the true order of
the planets in the solar system. The Earth was not the centre of the
universe but the third planet from the Sun.

Galileo Galilei’s observations in 1609 were the final breakthrough
for the theory that the Sun is the centre of the universe. Although
his book, Dialogue concerning the Two Chief World Systems,describes
how the planets orbit round the Sun, it was still not known why they
do so. Enter Isaac Newton (1642-1727), who developed laws of motion
and gravitation and established that gravity depends on the object’s
mass. An object with a greater mass will attract a smaller object.
The planets are therefore held in orbit round the Sun by the Sun’s
gravitation. Newton’s ideas were ground-breaking, but his theories
about gravity did not explain everything. More details fell into
place when Albert Einstein (1879-1955) established his theory of
relativity in 1905.

Related posts:

1. International Year of Astronomy 2009
2. International Year of Astronomy 2009 – Iceland
3. Europa 2009 – International Year of Astronomy
4. International Year of Astronomy 2009 – Korea
5. Europa-International Year of Astronomy 2009