The Sidereal Messenger
Galileo Galilei 1610
This short scientific report describes discoveries made by observing the night sky through a telescope. Follow Galileo as he tracks four small bodies moving around Jupiter.
78 pages 1h 31m reading time
- The first scientific work based on observations made with a telescope, and one of the founding texts of modern astronomy.
- Reports that the Moon is not smooth and perfect but rough, with mountains and valleys like the Earth.
- Shows that the telescope reveals many more stars than the naked eye can see, and that the Milky Way is made of countless stars packed close together.
- Its discovery of moons circling Jupiter gave strong support to the idea that the Earth goes around the Sun, since it proved that not everything in the sky circles the Earth.
- The four moons it describes are still called the Galilean moons, and the book helped make the telescope a basic tool of science.
Moons named for a patron
Galileo called Jupiter's moons the "Medicean Stars" to honor the Medici rulers, and won a court post from them.
Rushed into print
Galileo first saw Jupiter's moons in January and had the book printed in Venice about two months later.
Sold out in days
The first printing of 550 copies sold out within about a week.
Doubters refused to look
Some scholars at first doubted the discoveries, and a few reportedly refused even to look through a telescope.
Translated from Latin by Edward Stafford Carlos