Sun (Sol)

Norman Lockyer’s seven-prism spectroscope, 1868

This seven-prism spectroscope was designed to bend light into its different colours, allowing Norman Lockyer to identify different elements in stars. When observing the Sun he noticed the signature of a mystery element unknown on Earth. He named it ‘helium’ after the Greek word for Sun, helios. This element was only found on Earth decades later.
Kew Photoheliograph, 1857

This is the first instrument that was purpose built for astronomical photography. It was used at Kew and Greenwich to take daily photographs of the Sun. Warren de la Rue took this instrument to Rivabellosa in Spain to photograph the solar eclipse of 18 July 1860. The photographs were compared with ones taken 500 km away and proved that the prominences visible during an eclipse are part of the Sun, rather than an effect of the Earth’s atmosphere.
Photographs of sunspots taken with the Kew Photoheliograph, September 1870

These photographs are from a series taken in September 1870 with the Kew Photoheliograph, the large instrument at the very right of this showcase. Astronomers used it to take daily photographs of the Sun. Comparing the photographs day by day showed how features such as sunspots moved. We now know these dark spots are caused by magnetic activity on the Sun’s surface.
Epitome of the Almagest, 1496

This book summarises Claudius Ptolemy’s theories – the basis of astronomy for over a thousand years. Around AD 150, Ptolemy wrote a work in Greek outlining known theories of astronomy. During the Middle Ages this was lost in Europe, but translated and widely used by Arabic astronomers who called it al-majisti (the greatest). Latin and Greek translations of Arabic works brought Ptolemy’s ideas back to Europe in the 1400s. This copy of the book shows an early example of recycling: it is bound in vellum that was originally used for church music.
De revolutionibus celestium orbium (On the Revolutions of the Heavenly Spheres), 1543

Nicolaus Copernicus’s book, published shortly after the author’s death in 1543, offered scholars a new vision of the cosmos. Making the Sun rather than the Earth the centre of the universe offered a solution to many puzzling observations of the planets, although it would be many years before the controversial theory was widely accepted. This is a first edition of the book, one of only about 260 that survive.
Ptolemaic armillary sphere, 1500–99

This model depicts Ptolemy’s Earth-centred cosmos. The bands illustrate the motion of the Sun, Moon and stars. Armillary spheres were used in medieval times to teach priests how to calculate the hours of prayer at sunrise and sunset. Portraits of noblemen often included an armillary sphere to suggest wisdom and learning. More recently, novelist Umberto Eco chose the armillary sphere as a gruesome murder weapon in his 1983 book The Name of the Rose.
Copernican armillary sphere, 1807-46

With the Sun at the centre, this model demonstrates Nicolaus Copernicus’s vision of the cosmos. The central band shows the Sun’s apparent annual path through the zodiac, while the crossed bands mark the seasons. Copernican theory was firmly established by the time this model was made in the early 1800s. It includes recent discoveries such as the asteroids Ceres and Vesta. The model may have been used as a teaching aid or decorative item for a wealthy customer.
1:24 scale model of the zodiacal dials (Rashivalaya Yantra) at the Jaipur Observatory, India, 1884–86

The giant stone observatory at Jaipur was built for accuracy, to help improve the calendar. In 18th-century India people used a combination of the lunar-based Muslim and the solar-based Hindu systems. Both relied on observations made centuries earlier, so became increasingly unreliable. Jaipur’s ruler, Jai Singh II, commissioned the new observatory. This model shows one instrument called the Rashivalaya Yantra, with sundials to track the Sun through each zodiac sign.
Islamic horary quadrant, 1700-99

Horary quadrants determine the time from the altitude of the Sun. This Islamic instrument may have been used to calculate prayer times. Highly portable, it can be used from any location on Earth. The lines on the front represent the motion of the Sun across the sky.
Electrotype replica of a 16th-century mariner’s astrolabe, 1580-88

In the 1500s sailors needed to measure the angle of the Sun or the Pole Star above the horizon to help determine their latitude – not an easy thing to do on a pitching deck. The mariner’s astrolabe has cut-out sections to prevent buffeting from the wind and a heavy brass ring to keep it steady. This replica is based on an original thought to have been on board a ship in the Spanish Armada of 1588.
Lunar longitude calculator, 1880-85

This graph enabled sailors in the 1800s to calculate their longitude. First they would measure the angle between the Moon and prominent stars using a sextant. They then needed to do several calculations to work out their longitude – this graph helped to speed up the job. But it was still quite a laborious procedure, so when reliable chronometers were invented they soon became the preferred method of working out longitude.
Sextant, 1770-80

Until satellite navigation became widespread, this type of instrument was a vital tool for sailors and aviators. It is called a sextant because the metal arc is one-sixth of a circle. Looking through the coloured glass filters, an observer could measure the altitude of bright objects such as the Sun or Moon without risking eye damage. Captain Cook used a sextant similar to this one to navigate around the Pacific islands in the 1770s.