World’s Largest 17th-Century Astrolabe Breaks Auction Record in London

An 11th-century astrolabe revealing Islamic, Jewish, and Christian Astronomy. Credit: Nuncius / Brill / CC BY 4.0

A 17th-century brass astrolabe sold for much than 2 cardinal pounds ($2.75 million) astatine a Sotheby’s auction successful London, mounting a satellite grounds for immoderate astronomical instrumentality from the Islamic world.

The merchantability surpassed the erstwhile grounds held by an Ottoman astrolabe made for Sultan Bayezid II, a smaller portion that sold for conscionable nether 1 cardinal pounds ($1.3 million) successful 2014.

The instrument, described by Sotheby’s arsenic possibly the largest of its benignant anywhere, had ne'er been publically displayed earlier appearing astatine the auction house’s London galleries.

Ancient Greece shaped a 2,000-year-old science

The past of the astrolabe stretches backmost acold earlier its highest successful the Islamic world. O. Neugebauer, a historiographer of mathematics and astronomy astatine Brown University, traced the instrument’s origins successful a 1949 study published successful the diary Isis.

Neugebauer showed that Ptolemy, the Greek-Egyptian mathematician moving astir 150 AD, already knew of the device. Ptolemy referred to it successful his work, the Planisphaerium, arsenic the horoscopic instrument, a word that predates the connection astrolabe and rules retired immoderate aboriginal summation to the text.

Claudius Ptolemy with an armillary sphere model. Credit: Wikimedia Commons / Public Domain

Neugebauer besides argued that the theoretical instauration of the astrolabe, a geometric method called stereographic projection, was apt known to the Greek astronomer Hipparchus arsenic acold backmost arsenic 150 BCE.

Synesius, a student penning astir 400 AD and a pupil of the mathematician Hypatia, recorded that Hipparchus was the archetypal to survey the unfolding of a spherical surface, which is the halfway rule that the astrolabe depends on.

Theon of Alexandria, moving astir 375 AD, aboriginal wrote a dedicated treatise connected the level astrolabe. That enactment was preserved done the writings of the Syriac student Severus Sebokht earlier 660 AD.

How the spider disc maps the celestial sphere

The instrumentality works by projecting the celestial sphere from its South Pole onto a level surface. A rotating disc called the spider, named for its web-like web of prima pointers, carries the 12 divisions of the zodiac and moves astir the halfway of the instrument.

Below it sits a fixed sheet engraved with skyline lines, altitude circles, and hr curves calculated for a circumstantial geographical latitude. Together, these parts let a idiosyncratic to find the time, way stars, and lick a scope of astronomical problems.

A uncommon 17th-century astrolabe, erstwhile owned by Jaipur royalty, is going up for auction successful 🇬🇧London.

– It worked similar an past “SUPERCOMPUTER” utilized to way stars, time, direction,& adjacent astrology.
– Sotheby’s expects it to merchantability for £1.5–2.5 million. pic.twitter.com/187i12nGPh

— Info Room (@InfoR00M) April 26, 2026

By the 8th century, cognition of the astrolabe had dispersed crossed the Islamic world. Production centers grew successful Iraq, Iran, North Africa, and al-Andalus, successful present-day Spain. By the aboriginal 17th century, Lahore, present portion of Pakistan, had go a starring hub of accumulation wrong the Mughal world.

The Lahore astrolabe that rewrote auction history

Two brothers, Qa’im Muhammad and Muhammad Muqim, built the sold portion successful Lahore for a Mughal nobleman. They belonged to the Lahore School, 1 of the astir respected astrolabe-making traditions of the era.

Refinements to the astrolabe were among the notable achievements of this era. Credit: Pom² / CC BY-SA 3.0 / Wikimedia Commons

The trade stayed wrong a azygous household and was passed down done generations. Only 2 astrolabes are known to person been jointly made by the brothers. The second, a overmuch smaller piece, is held astatine a depository successful Iraq.

The instrumentality was commissioned by Aqa Afzal, a nobleman who governed Lahore astatine the time. Originally from Isfahan successful Iran, helium served nether Mughal emperors Jahangir and Shah Jahan successful elder roles. Its ample size and good item bespeak his rank. The portion besides points to the wider involvement that Mughal rulers and courtiers held successful astronomy and astrology during this period.

Technical mastery that defined the Lahore school’s legacy

Benedict Carter, caput of Islamic and Indian Art astatine Sotheby’s, said the Lahore School was astatine its astir refined erstwhile this portion was produced.

He noted it brought unneurotic method accuracy, applicable function, and creator prime successful a mode that acceptable it isolated from older instruments from parts of the Middle East, which were often built for relation alone.

The instrumentality stands astir 46 centimeters (18.1 inches) tall, measures astir 30 centimeters (11.8 inches) successful diameter, and weighs 8.2 kilograms (18.1 pounds), making it astir 4 times the size of a emblematic 17th-century Indian astrolabe.

An exploded presumption of an astrolabe, an instrumentality that was invented by the Greek idiosyncratic Ptolemy. Credit: elrond / Wikimedia Commons / CC BY-SA 4.0

Sotheby’s reported it holds 94 cities, each recorded with its longitude and latitude, on with 38 prima pointers joined by elaborate floral designs, 5 precision-calibrated plates, and grade markings that interruption down to one-third of a degree.

Carter besides noted that the prima pointers transportation labels successful Persian alongside Sanskrit equivalents written successful the Devanagari script, reflecting a cross-cultural magnitude to the piece.

From Jaipur’s royal postulation to a London sale

The instrumentality erstwhile belonged to the royal postulation of Maharaja Sawai Man Singh II of Jaipur. After his death, it passed to his wife, Maharani Gayatri Devi, earlier moving into a backstage collection. Sotheby’s had said earlier the auction that its royal past and pristine information were expected to pull involvement from museums and collectors.

Dr. Federica Gigante of the Oxford Centre for History of Science, Medicine and Technology compared astrolabes to modern smartphones, noting they could cipher sunrise and sunset times, measurement the tallness of buildings oregon the extent of wells, and formed horoscopes erstwhile paired with an almanac.

She described them arsenic two-dimensional representations of a three-dimensional universe. Gigante added that this peculiar portion is remarkably accurate, susceptible of giving the nonstop grade of altitude of a celestial body, and that the lone comparable instrumentality is apt 1 built for Abbas II of Persia.