"We lead a fascinating life, and we want others to share in it too," Catherine Cesarsky, president of the Paris-based International Astronomical Union (IAU), told a press conference.

A total of 136 countries are taking part in the celebration, throwing open the doors of observatories and staging seminars and exhibitions to promote interest in astronomy.

"People have always looked to the sky for answers to the questions, 'how did we get here?' and 'why are we here?'" said Koichiro Matsuura, director-general of the UN Educational, Scientific and Cultural Organisation (UNESCO), hosting the two-day official launch. "The sky belongs to everybody."

One cornerstone project is called "100 Hours of Astronomy." Running from April 2-5, it aims at getting as many people as possible to look through a telescope and observe the stars and planets.

Astronomers are also pushing a gadget called the "Galileoscope," a free, easy-to-assemble telescope that could be distributed in the millions.

One of the popular events for 2009 will be a total solar eclipse on July 22, occurring in Nepal, Bangladesh, Bhutan, Myanmar and China.

2009 was chosen for the Year of Astronomy as it is the 400th anniversary of an "annus mirabilis," when Galileo used a telescope to make man's first magnified observations of the heavens.

With it, the Italian philosopher made radically new drawings of the Moon and discovered four satellites around Jupiter, which are called the Galilean moons today in his honour.

These and other observations prompted Galileo to conclude that the Earth revolved around the Sun, and not the other way round -- a view that led to his conviction for heresy by the Catholic Church and the banning of his work.

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