By Duncan Kennedy
BBC News, Rome
Early telescopes and model celestial globes are on display
A new exhibition marking the 400th anniversary of Galileo's work is set to open in the Vatican.
The Catholic Church once labelled Galileo, now regarded as modern astronomy's founding father, a heretic.
He was tried for challenging the widely held belief that the Sun travelled around the Earth.
Nicolas Copernicus did much ground-breaking work on the link between the Sun and the Earth, but it was Galileo's instruments that proved the theory.
It was not until 1992 that Pope John Paul II declared that the Church's ruling was an error and that Catholics were not hostile to science.
Now a selection of Galileo's instruments - along with those of other key figures in astronomy - is being put on display in the Vatican.
There will also be some of Galileo's original documents in which he excitedly recorded his first discoveries.
The exhibition runs until January.