Royal Observatory Edinburgh

Henderson and Alpha Centauri

Henderson (Dundee, 28 December 1798 – Edinburgh, 23 November 1844) trained as a lawyer and worked his way up through mathematical astronomy, notably lunar occultations for the Nautical Almanac, before serving as His Majesty’s Astronomer at the Cape of Good Hope in 1832–33. Tipped off that Alpha Centauri had a large proper motion — a hint of proximity — he took declination and right-ascension measurements that contained, as the specialist 2005 paper “Thomas Henderson and α Centauri” puts it, “the first observations containing evidence of a measurable stellar parallax”.

From his parallax Henderson derived a distance of roughly 3.25 light years. The modern parallax for the system is 0.742″, or 4.396 light years, so his figure was about a quarter too small — 25.6 per cent — but of the right order, which was the point that changed astronomy. He continued at Calton Hill until his death in 1844, accumulating a very large body of stellar positions.

Piazzi Smyth: Two Records

Charles Piazzi Smyth (Naples, 3 January 1819 – 1900) became second Astronomer Royal for Scotland in 1846. The Astronomical Institution wound up the following year and the observatory passed to Treasury control, beginning decades of underfunding; most of Smyth’s best work was done elsewhere.

His 1856 Tenerife expedition is the strongest of it. Backed by an Admiralty grant of £500, he left England on 24 June 1856 aboard the yacht Titania, lent by the railway engineer and MP Robert Stephenson, and observed from Mount Guajara at about 2,700 metres and Alta Vista at about 3,260 metres on Teide. The declared aim was “to ascertain how much astronomical observation can be benefited, by eliminating the lower third or fourth part of the atmosphere”. His Report on the Teneriffe Astronomical Experiment of 1856 and his paper in the Philosophical Transactions (vol. 148, 1858, read 18 June 1857) showed that height transformed image quality, confirming a conjecture of Newton’s from 1704. This was the first experiment designed to demonstrate the advantage of altitude — not the first high-altitude observation, since isolated earlier ones exist, such as de Plantade at the Pic du Midi in 1741 — and it makes Smyth a fair candidate for father of mountain astronomy, vindicated worldwide a century later.

On Tenerife he also measured the Moon’s radiant heat and found the signal stronger at altitude: the first evidence that the atmosphere absorbs infrared radiation. He was not the first to detect lunar heat — Macedonio Melloni did that in 1846 — and his measurements were crude by later standards, but they were pioneering. At home he built Edinburgh’s time service: the time ball on Nelson’s Monument, dropped at one o’clock from 1853 or 1854, and the One O’Clock Gun at the Castle from 1861, for synchronising ships’ chronometers at Leith. Both survive. His solar-spectrum work won the Makdougall Brisbane Prize in 1880.

And then there is the other record. From the early 1860s Smyth adopted John Taylor’s ideas and became the leading evangelist of pyramidology, claiming that the Great Pyramid of Giza encoded divinely significant units — the “pyramid inch”. It was rejected by the scientific establishment and decisively undermined when Flinders Petrie’s 1880 survey found the pyramid smaller than the theory required. Sir James Young Simpson is said to have remarked that his measurements were most exact but his logic most wretched. When the Royal Society declined his pyramid papers, Smyth resigned his Fellowship in protest — the only person ever to have done so. He resigned the Astronomer Royal post separately in 1888, in protest at the observatory’s condition. The pyramid work is a discrediting eccentricity, entirely separate from the astronomy.

The Move to Blackford Hill

By 1888 the observatory was, in ROE’s own summary, “at a very low ebb with inadequate buildings, outmoded instruments, an unsuitable site and a paltry budget”. A Royal Commission recommended it cease to be a national institution and pass to the University. The growing city’s smoke and lights had ruined the observing conditions.

What saved it was a gift. James Ludovic Lindsay, 26th Earl of Crawford, offered the nation the instruments of his private Dun Echt observatory in Aberdeenshire together with his astronomical library — the Crawford Collection, roughly 15,000 items and ranked among perhaps four truly great collections of astronomical books in the world, containing a first edition of Copernicus’s De Revolutionibus (1543) annotated by Erasmus Reinhold, Galileo’s Sidereus Nuncius (1610) and a 1687 Principia with Samuel Pepys’s imprimatur — on condition that the government build and maintain a new Royal Observatory.

The chosen site was Blackford Hill, south of the city. Construction began in 1892 to a design under W.W. Robertson of HM Office of Works, estimated at £30,000 and built by W. and J. Kirkwood; the building was completed in 1895 and opened on 7 April 1896 by Lord Balfour of Burleigh, Secretary for Scotland. Ralph Copeland, third Astronomer Royal for Scotland and formerly Crawford’s chief astronomer at Dun Echt, oversaw the move. The first main instruments were a 15-inch refractor and a 24-inch reflector, with an 8.5-inch transit circle. Calton Hill reverted to the City Council as the City Observatory.

Astronomers Royal for Scotland

Ralph Copeland (1837–1905; in office 1889–1905) was a versatile observer who discovered 35 NGC objects, including the Copeland Septet of galaxies in Leo, did pioneering high-altitude spectroscopy in the Andes, and established the observatory’s time and meteorological services. Sir Frank Watson Dyson (1905–1910) left to become the English Astronomer Royal, the only person to hold both offices, and went on to organise the 1919 eclipse expeditions that tested general relativity and to introduce the BBC’s six pips. Ralph Allen Sampson(1910–1937) worked on the motions of Jupiter’s Galilean satellites, winning the RAS Gold Medal in 1928, and on stellar colour temperatures; he installed the 36-inch reflector. W.M.H. Greaves, Hermann Brück, Vincent Reddish and Malcolm Longair follow to 1990.

One night intrudes on the astronomy. On 21 May 1913, around one in the morning, a bomb attributed to militant suffragettes exploded at Blackford Hill, cracking the masonry of the West Tower and splintering internal floors but leaving the telescope undamaged. Nobody was hurt and nobody was ever charged. A note was found nearby: “How beggarly appears argument before defiant deed. Votes for women.” The observatory employed only men at the time.

From Positions to Astrophysics

Blackford Hill turned from measuring where stars are to asking what they are made of. In 1907 the observatory joined the international Carte du Ciel photographic sky-mapping project — over-ambitious for the technology, but its first venture into photographic surveys. In 1930 a 36-inch Cassegrain reflector by Grubb Parsons of Newcastle was installed in the East Dome, then the largest telescope in Britain; it survives, non-operational, in the Visitor Centre. A 16/24-inch Schmidt camera followed in 1951, going to the National Museum of Scotland in 2010.

Under Hermann Brück (1957–1975) the place was transformed: staff grew from about ten to about a hundred, professional engineers were recruited, electronics, automation and computing arrived, and in 1967 Edinburgh’s modern Astrophysics degree was created with his wife, the astronomer and historian Mary Brück. The automated plate-measuring machines GALAXY, COSMOS and SuperCOSMOS pioneered machine measurement of photographic plates.

From the 1970s the observatory built or ran major telescopes abroad, earning the description “the observatory on which the sun never sets”: the UK Schmidt Telescope at Siding Spring in Australia from 1973; the UK Infrared Telescope on Mauna Kea, built 1975–78, a 3.8-metre instrument with a pioneering thin primary mirror; and the James Clerk Maxwell Telescope, opened on Mauna Kea in 1987, at 15 metres the world’s largest single-dish submillimetre telescope. Maxwell himself was never on the staff; the name is a commemoration, and his Saturn’s-rings proof of 1857 belongs to his Aberdeen years.

Building Instruments for the World

In the mid-1990s UK astronomy was reorganised: the overseas observatories were run separately, the Royal Greenwich Observatory was closed, and instrument-building was concentrated in one place. The UK Astronomy Technology Centre was formed on Blackford Hill in 1998 from the technology departments of the ROE and the Cambridge-based Royal Greenwich Observatory, as part of the Science and Technology Facilities Council.

Its record is specific rather than vague. It provided the instrument science leadership for MIRI, the Mid-Infrared Instrument on the James Webb Space Telescope launched on 25 December 2021 — its director, Professor Gillian Wright, is the European Principal Investigator, and the UK invested nearly £20 million in development, with MIRI built by teams across ten European countries and the United States in partnership with NASA’s Jet Propulsion Laboratory. It built the SCUBA and SCUBA-2 submillimetre cameras for the JCMT and SPIRE for ESA’s Herschel Space Observatory; project-managed VISTA, the four-metre infrared survey telescope handed to ESO in 2009 as part of the UK’s membership contribution and now at Paranal; and continues with instruments for Gemini, KMOS and MOONS for the Very Large Telescope, HARMONI for the Extremely Large Telescope, software for the Square Kilometre Array and optical benches for the LISA gravitational-wave mission.

One Name, Four Organisations

Between 1834 and 1990 one person held three offices at once: Regius Professor of Astronomy, Astronomer Royal for Scotland, and Director of the Royal Observatory. The 1990s reorganisation separated them. From 1995 the title Astronomer Royal for Scotland became honorary and independent of the Edinburgh directorship, held by John Campbell Brown (1995–2019) and, from May 2021, by Catherine Heymans, the first woman in the post.

“Royal Observatory Edinburgh” is now an umbrella name for the bodies sharing the STFC-owned Blackford Hill site: the UK Astronomy Technology Centre; the Institute for Astronomy of the University of Edinburgh, the research and teaching descendant of the old government observatory, home to the plate library and SuperCOSMOS; the Higgs Centre for Innovation, opened in 2018 as an STFC and University incubation and space-technology hub named for the Nobel laureate, with partners including ESA, the UK Space Agency and CERN; and the ROE Visitor Centre.

Timeline

1. 1583

   Astronomy taught from the founding of Edinburgh's college

   Portable instruments; no permanent observatory

2. 1776

   Foundation stone laid on Calton Hill

   Thomas Short's popular/commercial venture, not the national institution

3. 1785

   Regius Chair of Practical Astronomy created

   By warrant of George III; Robert Blair treats it as a sinecure

4. 1792

   The Old Observatory completed

   James Craig's Gothic tower, much reduced from the original plan

5. 1811

   The Astronomical Institution of Edinburgh founded

   John Playfair its first president

6. 1818

   Work begins on the Playfair Building

   W.H. Playfair's Greek temple on Calton Hill

7. 1822

   George IV confers the Royal title

   “Royal Observatory of King George the Fourth”

8. 1831–1834

   Instrumentation finally completed

   A government grant delivers the transit telescope

9. 18 Aug 1834

   Thomas Henderson appointed

   First Astronomer Royal for Scotland; £300 a year

10. Jan 1839

    Henderson announces the Alpha Centauri parallax

    Two months after Bessel's 61 Cygni result of 1838

11. 1846

    Charles Piazzi Smyth succeeds Henderson

    The Institution winds up in 1847; Treasury control and underfunding follow

12. 1853/54 and 1861

    The time ball and the One O'Clock Gun

    Smyth's time service for Leith shipping

13. 1856

    The Tenerife high-altitude experiment

    The first dedicated demonstration that altitude improves seeing

14. 1888

    Crawford's gift averts closure

    Instruments and library offered on condition of a new observatory

15. 21 May 1913

    A bomb explodes at the observatory

    Attributed to militant suffragettes; the West Tower masonry cracked

16. 7 Apr 1896

    Blackford Hill formally opened

    Ralph Copeland oversees the move; Calton Hill becomes the City Observatory

17. 1930

    The 36-inch Grubb Parsons reflector installed

    Then the largest telescope in Britain

18. 1957–1975

    The Brück transformation

    Staff from about ten to about a hundred; the 1967 Astrophysics degree

19. 1973–1987

    UKST, UKIRT and the JCMT

    “The observatory on which the sun never sets”

20. 1998

    The UK Astronomy Technology Centre formed

    From the ROE and Royal Greenwich technology departments

21. 2018

    The Higgs Centre for Innovation opens

    Named for the Nobel laureate; STFC and University partnership

Did You Know?

• The first holder of Edinburgh's astronomy chair never taught and had no telescope; the post was a sinecure for 43 years.
• Edinburgh's One O'Clock Gun, fired since 1861, was set up by an Astronomer Royal who also believed the Great Pyramid encoded divine measurements.
• Piazzi Smyth is the only person ever to resign a Fellowship of the Royal Society in protest.
• Smyth sailed to Tenerife on a yacht lent by Robert Stephenson, son of the locomotive engineer.
• The observatory's survival was bought with a private library containing a Copernicus first edition annotated by Erasmus Reinhold.
• A suffragette bomb cracked the West Tower in 1913 without touching the telescope.
• Frank Watson Dyson is the only person to have been both Astronomer Royal for Scotland and Astronomer Royal.
• Blackford Hill instruments now sit at Paranal, on Mauna Kea and a million miles from Earth aboard James Webb.

Honest Caveats

Henderson did not measure the first stellar parallax. He observed first and published second; Bessel holds priority and took the Gold Medal.

1776 is not the founding of the Royal Observatory. It is the start of a commercial venture on the same hill.

Smyth’s Tenerife “first” needs its qualifier: the first dedicated experiment demonstrating the benefit of altitude, not the first observation from height. His infrared “first” is atmospheric absorption, not the detection of lunar heat, which Melloni achieved in 1846.

Pyramidology is not part of the scientific record. It is presented here as discredited.

“Britain’s first astronomical society” for the 1811 Institution is traditional and plausible — the Astronomical Society of London came in 1820 — but rests largely on the observatory’s own accounts.

Minor dates vary by source: the Regius Chair (1785 or 1786), the time ball (1853 or 1854), the 36-inch reflector (1928 manufacture, 1930 installation) and Smyth’s appointment, sometimes wrongly given as 1845 rather than 1846.

Maxwell was never on the staff. The telescope and the building carry his name by commemoration.