Near the Moon’s western limb lies Oceanus Procellarum, the Ocean of Storms — a vast swath of terrain spanning 1,600 miles (2,500 kilometers) north to south, and covering 10.5 percent of the lunar surface. Its hinterland is peppered with a teeming sea of craters. One of them, at its southeastern extremity, honors Britain’s first Astronomer Royal, John Flamsteed.
Ancient and worn, it is 13 miles (21 km) wide, its bulging rim tumbling 1.4 miles (2.2 km) to a rubble-strewn floor. Flamsteed is one of several Moon craters named for one of the 15 men who since 1675 were Britain’s foremost astronomers. Others are recognized with asteroids or Mars craters, and one — Edmond Halley — loans his name to Halley’s Comet.
For 350 years, astronomers royal have advised British monarchs on the stars and more: from navigation to mapmaking, timekeeping to railway gauges, wind energy to geoengineering, robotics to climate change and even the existential survival of humanity.
Nine of these astronomical titans were knighted for their services, and today’s incumbent — Professor Sir Martin Rees, Baron Rees of Ludlow — holds a lifelong peerage in Britain’s House of Lords. But when the first astronomer royal arrived in London one February morning in 1675, he could hardly have imagined what lay ahead.
The first astronomer royal
Flamsteed came from the English county of Derbyshire. His father ran a malting business, soaking and drying cereal grains for beer. The boy had a shrewd knowledge of arithmetic and fractions and solidly grasped the scientific lingua franca of the day: Latin.
A love of astronomy bloomed when Flamsteed observed a partial solar eclipse. Fascinated by timekeeping and sundials, he penned his first scientific paper aged 19 and became a church deacon. Flamsteed’s life might have settled into bucolic obscurity but for one man, his wealthy patron and England’s surveyor-general: Sir Jonas Moore.
Moore petitioned King Charles II to build a London observatory — and it came about in the unlikeliest of circumstances. During the Age of Sail, mariners could not accurately measure longitude when out of sight of land. But the king’s mistress, Louise de Kérouaille, heard a proposal to use the Moon to determine longitude at sea.
Charles appointed a royal commission whose panel included architect Sir Christopher Wren, astronomer Robert Hooke, and politician Silius Titus. It was Titus who brought Flamsteed to London in February 1675. The young astronomer was assigned to test the proposal — but quickly dismissed it as unworkable.
However, the commission persuaded the king to fund an observatory and hire an astronomer to map the stars and lunar motions, and solve the longitude problem. On March 4, Flamsteed was appointed the “King’s Astronomical Observator” with a £100 annual stipend (equal to about £17,200, or nearly $23,000, today).
A royal warrant commanded Flamsteed “forthwith to apply himselfe with the most exact care and diligence to rectifieing the Tables of the motions of the Heavens, and the places of the fixed stars, so as to find out the so much desired Longitude of places for Perfecteing the art of Navigation.” Another warrant in June created the Royal Greenwich Observatory, with Flamsteed laying its foundation stone in August.
He was never titled “Astronomer Royal” in his lifetime — only “Our Astronomical Observer,” with similar terms used for Flamsteed’s successors. But the Astronomer Royal name worked its way into popular parlance in the 18th century and included the directorship of Greenwich until 1972.
A career of achievements
Flamsteed won praise for high standards and meticulousness, but became enmired in a bitter dispute with Sir Isaac Newton, president of the Royal Society. Newton was frustrated by Greenwich’s lack of publications under Flamsteed. He obtained warrants for the Royal Society to scrutinize the observatory’s work.
Unwilling to risk his reputation by publishing unverified data, an incensed Flamsteed kept his records sealed. But Newton and Edmond Halley — Flamsteed’s former assistant — obtained them and published a pirated star catalog. Flamsteed gathered 300 of the catalog’s 400 prints and burned them. “If Sir I.N. would be sensible of it,” he wrote, “I have done both him and Dr. Halley a great kindnesse.”
After Flamsteed’s death in 1719, his work was published thanks to his widow: a vast opus of lunar tables, planetary motions, and 2,935 cataloged stars. It earned the astronomer royal and Greenwich plaudits for the exactness of their observations.
Nor should Margaret Flamsteed’s contribution be minimized. Twenty-four years Flamsteed’s junior, the diaries of this highly literate and numerate woman reveal a shared love of astronomy. She observed with her husband — “solus cum sponsa” (“alone with wife”), Flamsteed wrote — and penned his letters when the old man’s hands became shaky. Following his death, and at great expense to herself, in 1725 and 1729 she published Flamsteed’s Historia Coelestis Britannica and Atlas Coelestis, respectively— the largest, most accurate, and most comprehensive star atlases of their time. Through Margaret’s efforts, the role of the Astronomer Royal and the institution of Greenwich itself were elevated to the forefront of astronomical research in the 18th century.
Flamsteed also made one of the earliest recorded sightings of Uranus in 1690, a century before the planet was found. He mistook it for a star, cataloging it as 34 Tauri.
Centuries of accomplishments…
The first six astronomers royal — Flamsteed, Edmond Halley, James Bradley, Nathaniel Bliss, Nevil Maskelyne, and John Pond — devoted themselves to longitude and navigation. This is unsurprising given that Greenwich was administered by the Board of Ordnance and later the British Admiralty.
In 1731, Halley showed longitude was indeed measurable using lunar motions. His method claimed to be accurate to within 69 miles (111 km) near the equator and marked one of the most exact calculations before the introduction of marine chronometers. And in 1767, Maskelyne founded the Nautical Almanac for convenient, year-round determination of longitude for seafarers.
During his tenure, Bradley measured the speed of light as taking 8 minutes 12 seconds to travel between Earth and the Sun — only 1.3 percent too high. He also mapped more than 60,000 stars so precisely that his charts remained in use into the 20th century.
Using Maskelyne’s observations, Charles Hutton was able to calculate Earth’s density as 4.5 times that of water, slightly lower than today’s value of 5.515. And in 1781, when William Herschel discovered Uranus, the pair shared their joy at finding a new planet. “I don’t know what to call it,” Maskelyne wrote. “It is as likely to be a regular planet moving in an orbit nearly circular round the Sun as a comet.”
Greenwich has long been synonymous with timekeeping. In 1833, Pond installed a red time-ball that rises up a mast, then falls at exactly 1:00 p.m., providing a public signal for mariners and others near the observatory to synchronize clocks with Greenwich Mean Time. And in 1924, Astronomer Royal Frank Watson Dyson introduced the six pips — a series of short beeps used by BBC radio stations to mark the change of each hour.
Astronomer Royal George Biddell Airy established the prime meridian at Greenwich, where it remained the international meridian from 1884 to 1984. (Since 1984, the international meridian has been about 336 feet [102.5 meters] to the east of the historical meridian.) Marked by a brass (and later steel) strip in the observatory’s courtyard, since 1999 the original prime meridian has been projected across London’s skies by a powerful green laser.
…and some mistakes
But astronomers royal also got themselves into hot water. In 1846, Airy failed to act when astronomer John Couch Adams approached him with data predicting the location of an eighth planet. Weeks later, two German astronomers discovered Neptune, snatching glory from Britain’s grasp and exposing Airy to a media mauling. However, more recent reinterpretations suggest that the imprecise nature of Adams’ calculations gave Airy pause before committing to a search that, for Britain, would prove too late. It has been speculated that Airy “sacrificed himself on the altar of British astronomy,” as the Linda Hall Library’s William B. Ashworth Jr. writes, securing Adams’ and Britain’s role in the discovery of Neptune, but at the expense of losing some credibility himself.
It was not Airy’s only brush with misfortune. Railway engineers consulted him about wind speeds and pressures before building a bridge over Scotland’s River Tay. But in 1879, as a train passed over it in a savage windstorm, the bridge collapsed, killing scores of passengers. Airy was harshly criticized for his advice.
On the eve of the Space Age, Astronomer Royal Harold Spencer Jones insisted that “generations will pass before man ever lands on the Moon” with “little hope of his succeeding in returning to Earth and telling us of his experiences.” And his successor, Richard Woolley, called space travel “utter bilge…it’s all rather rot.”
More to come
For 350 years, astronomers royal morphed from seekers of longitude to Britain’s go-to guys for science, education, and technology. In the words of the present incumbent, Professor Sir Martin Rees, astronomy’s power to transcend national and cultural boundaries reveals much about the cosmos and ourselves.
“Most educated people are aware that we’re the outcome of billions of years of evolution, but they tend to feel we’re somehow the end of it,” Rees told New Statesman. “We’re less than halfway through the Sun’s life — there is as much time ahead as it has taken for us to emerge from the primordial slime. Astronomy does give one a feeling about the long-range future.”
