Illustration from "Le Grand Atlas de Cosmografie Blaviane," by the Dutch cartographer Johan Blaeu, showing Tycho Brahe's Uraniborg observatory on the island of Hven, Denmark. Riccardana Library; Florence, Italy.

Illustration from "Le Grand Atlas de Cosmografie Blaviane," by the Dutch cartographer Johan Blaeu, showing Tycho Brahe's Uraniborg observatory on the island of Hven, Denmark. Riccardana Library; Florence, Italy.

Illustration from "Le Grand Atlas de Cosmografie Blaviane," by the Dutch cartographer Johan Blaeu, showing Tycho Brahe's Uraniborg observatory on the island of Hven, Denmark. Riccardana Library; Florence, Italy.

Illustration from "Le Grand Atlas de Cosmografie Blaviane," by the Dutch cartographer Johan Blaeu, showing Tycho Brahe's Uraniborg observatory on the island of Hven, Denmark. Riccardana Library; Florence, Italy.

Illustration of an equatorial armillary sphere, containing one and a half circles, in Tycho Brahe's observatory. From "Le Grand Atlas de Cosmografia Blaviane," by the Dutch cartographer Johan Blaeu. Riccardana Library; Florence, Italy.

Illustration of the "Leviathan of Parsonstown," a 72-inch reflecting telescope built in the 1840s by William Parsons, 3rd Earl of Rosse, on his estate in Parsonstown, Ireland. The telescope mirror was made from speculum metal, which tarnished so quickly that it had to be repolished every six months.

Illustration from "Le Grand Atlas de Cosmografie Blaviane," by the Dutch cartographer Johan Blaeu, showing Tycho Brahe's Uraniborg observatory on the island of Hven, Denmark. Riccardana Library; Florence, Italy.

Quadrant was used by Hevelius in the 17th century to measure the position of celestial bodies.

A map of the world, taken from Ptolemy's book "Geographia."

Astronomical clock.

An astronomical sextant belonging to Tycho Brahe (1546-1601), the Danish astronomer, astrologer and alchemist. After becoming interested in astronomy as a student in Copenhagen, Tycho Brahe realized the difficulty of making accurate measurements of celestial bodies with the instruments of the day. His designs for new methods and devices won him great fame. He was granted an estate on the island of Hven to conduct his research, and funding to built the Uraniborg observatory. From there he generated the most accurate astronomical data of his time. He was exiled to Prague in 1597 and was assisted in his work there by Johannes Kepler until his death. Due to a duelling injury at university, he always wore a metal nose prosthetic.

An illustration showing a person calculating the angle between Aldebaran (the brightest star in the constellation Taurus) and the moon, with respect to the ecliptic.

An eighteenth century illustration of a celestial sphere, or rather a representation of the hemisphere of the heavens that can be seen from the northern half of Earth. The moveable horizon can be adjusted to represent the horizon of any observer, whether at the equator or the north pole, but it always cuts the ecliptic at 0 degrees Aries and 0 degrees Libra.

Christoph Scheiner (c.1573-1650), a German Jesuit father, physicist and astronomer, and a co-discoverer of sunspots.

Provided with a model of the celestial sphere, reference books and dividers, a medieval astrologer draws up a horoscope in this engraving from Robert Fludd's "History of Two Worlds." A celestial sphere is a representation of the heavens as seen from Earth.

An equatorial telescope, mounted so that it has two axes of motion at right angles to each other, one parallel to the axis of the earth.

In 1575, when the Ottoman empire was at its height, the astronomer Taqi ad-Din founded an observatory at Galata (now part of Istanbul, Turkey). This painting of the time shows the astronomers with their equipment, which includes a globe, a sand glass for timing, items for drawing, and all kinds of sighting devices.

An illustration of the northern hemisphere of a brass celestial globe belonging to Major-General Sir John Malcolm. The brass globe was made by Muhammad ibn Hilal, possibly from Maragha, north-west Iran, AD 1275-76.

An illustration of the southern hemisphere of a brass celestial globe belonging to Major-General Sir John Malcolm. The brass globe was made by Muhammad ibn Hilal, possibly from Maragha, north-west Iran, AD 1275-76.

A meridian circle or transit circle, an instrument for observing the time of stars passing the meridian, while also measuring their angular distance from the zenith. Tycho Brahe was the first to construct a large meridian quadrant.