Two Galileo exhibitions in and showcase ancient astronomical instruments like sundials, astrolabes and orreries
Galileo’s Telescope (1610)
Perhaps the most famous of Galileo’s scientific instruments was the telescope. This photo shows Galileo’s original 1609 invention.
It was modelled after telescopes produced in other parts of Europe that could magnify objects three times. Galileo’s could magnify objects twenty times.
Galileo’s telescope up close
With his telescope, Galileo was able to look at the moon, discover the , observe a supernova, verify the phases of Venus, and discover sunspots.
provided observational proof of the Copernican system: that the Earth and other planets revolve around the sun.
Prior to Galileo’s time, it was held that the universe was geocentric, meaning the sun revolved around the Earth.
Polyhedral dial (16th century)
The onset of the Renaissance saw an explosion of new designs for sundials, including this example of the .
This sundial has nine . All the dials on all the different faces show exactly the same time, no matter which face is used.
It is a very fine example of how science and art fused during the Renaissance, creating not only functional but beautiful scientific instruments.
The interest in the passage of time is partly philosophical and partly practical. Philosophically, people were learning that their method of measuring the passage of time was, ultimately, directly connected to orbital motion – either the Earth’s or the sun’s.
Practically, navigators knew they needed an accurate time reference to accurately determine longitude at sea. Having such a device would allow mariners to more easily reach distant lands (and potential revenue sources) with less risk.
Brass astrolabe (9th century)
This particular astrolabe dates from the time of the first Holy Roman Emperor, , around 832 AD. It uses two plates for latitudes corresponding to the regions between Persia and the Black Sea.
Astrolabes are portable astronomical calculators used to tell the rising and setting times of the sun, and a number of fixed stars, in several locations. They can also be used to determine height and distance by the geometric method of .
Orrery (18th century)
was very active in spreading knowledge of Newtonian astronomy. In his widely read he suggested the idea of building planetariums, known as orreries, which would clearly explain the “celestial mechanism”. That is, by the accurate use of gears it was possible to reproduce the motions of the heavens.
The London scientific instrument manufacturer had called this type of planetarium an orrery, in honour of , 4th Earl of Orrery.
This orrery of Venus is a product of the workshops of the in Florence, and follows the example set by Ferguson. It worked by winding a crank, and exactly reproduced the heliocentric motions of Mercury, Venus and the Earth, as well as that of the moon around the Earth.
Planetary motion tapestry (15th century)
This tapestry depicting complex geometrical and allegorical planetary motion of the universe is from , Spain.
At the centre of the tapestry is a celestial sphere, which is projected onto a plane so that it assumes the form of an astrolabe kept in motion by two angels, one of whom is winding a handle while the other pushes round the circle of the .
At the centre of the sphere, and of the tapestry itself, shines the , which is surrounded by three circles representing the Arctic Circle.
The extrazodiacal constellations of the southern hemisphere are identified by their Latin names. Also, the Latin text above the astrolabe explains that the sphere of the earth revolves around the polar axis surrounded by the , exercising its influence upon mankind.
God is shown as the “First Mover”, giving motion to the sphere of the world supported by the kneeling figure of .
Navicula dial (15th century)
This is an extremely rare sundial known as a navicula dial, or , because its shape resembles that of a small boat.
Despite its unusual shape, it works much like a nautical astrolabe, telling time and latitude by the sun’s position.
Measuring instrument (1568)
Its name evokes the eighth introduced by Islamic astronomers to explain the : the gradual change of the Earth’s rotational axis against the background of the fixed stars. However, this “instrument of the Primum Mobile” is basically a device to determine the sine and cosine of an angle.
, otherwise known as Apianus, predicted a use for it in astronomy, analogous to that of a portable quadrant.
This example, the only one known today, is signed “F.E.D.P.F.”, standing for “Frater Egnatius Dantis Predicatorum Fecit”. It bears the arms of the , indicating that it was made for the by . It does in fact come from the Medici collections.
Lunar Observations by Galileo (1609)
These watercolours represent the Moon in different phases and demonstrate the superiority of Galileo’s telescopes to those of his contemporaries.
At the upper right, just above the image marked “1”, an isolated crater is shown in detail.
Graphometer (17th century)
Used to measure angles from 0 to 180°, could determine positions and distances by triangulation, both on land and at sea, relative to magnetic north or a prevailing wind.
Linder Gallery interior (17th century)
This painting is of the interior of a gallery belonging to .
You can see mathematical and astronomical instruments, diagrams illustrating the main cosmic systems, and books by .
This picture shows the high profile that astronomy had achieved in art and mirabilia collections.
Armillary sphere (1578)
This astronomical instrument is used to represent the orbits of the planets, stars, and the sun by means of rings pivoting on a common center.
Typically, at the center is a large globe representing the Earth. Surrounding brass rings portray celestial coordinates, meridians, equators, and zodiac constellations.
were first developed in Asia in the 4th century BCE and came into use in Europe by the 10th century. They are essentially the 3D version of astrolabes. The modern equivalent is the planetarium.
Middle finger of Galileo’s right hand
The power of Galileo’s observations in supplanting religious ideology is best captured in this image of his finger.
It was detached from his remains in 1737 and encased in glass and gilt, pointing heavenward: a scientific reliquary for a secular saint.
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Galileo: Around the sun and back
