Last week, the <a href="https://www.thenational.ae/uae/science/first-pan-arab-space-organisation-formed-in-abu-dhabi-1.838870">first pan-Arab space group</a> was formed in Abu Dhabi. Its first project, a satellite that will <a href="https://www.thenational.ae/uae/government/pan-arab-satellite-to-monitor-pollution-to-be-built-in-al-ain-1.839504">monitor climate change</a>, was announced by Sheikh Mohammed bin Rashid. The Vice President and Ruler of Dubai said it would be named 813, a reference to the year that marked the beginning of prosperity for the House of Wisdom in Baghdad during Al Mamun's reign. He said the year was a symbol of Arab and Islamic excellence in science and astronomy – but what exactly happened that year? He was known simply as Al Mamun, although his full name was Abu Al Abbas Al Mamun ibn Harun Al Rashid. He was the seventh caliph of the Abbasid empire, succeeding to the title aged 27. It was the year 813 and Baghdad was the at the heart of the Abbasid empire, a dynasty descended from Prophet Mohammed’s uncle, not just politically and militarily but also intellectually. The caliph ruled over a vast area of territory than extended from Persia to present-day Tunisia. It included the Arabian Peninsula, all of the Levant, along with Egypt, and the island of Crete. This was the dawn of the golden age of Islam, an explosion of science, culture and learning that would last 600 centuries and draw knowledge from all over the world. There were no challengers. Europe, in those years, was struggling out of the dark ages, its most powerful ruler, the Frankish king Charles, also known as Charlemagne, on his deathbed. Baghdad was at the heart of the empire and there, Al Mamun’s father, Harun, the fifth caliph, had created a large private library that became known as Khizanat Al Hikma, or the Library of Wisdom. Harun died in 809. He was succeeded by his son, Al Amin, whose reign as caliph lasted less than four years. His early death was the result of war fought with his half-brother Al Mamun. The two siblings had never liked each other, resulting in a civil war and Al Amin’s execution on the battlefield. Conflict gave way to peace. Almost his first act as caliph was an order from Al Mamun to expand the Library of Wisdom that was close to overflowing. Separate wings were constructed for the different disciplines of knowledge. The new building included scientific texts from all over the world and collected works in other languages, most notably the great Greek philosophers from Aristotle to Plato. From 813, it was known as Bayt Al Hikma, or the House of Wisdom. The new institution drew scholars from across the Islamic world, meeting under one roof to debate and discuss. Many produced their own notable works. Among them was the brilliant Persian mathematician, Muhammad Al Khwarizmi, whose great work <em>Kitab Al Jabe</em>r gives us the word algebra. Al Khwarizmi was also responsible for importing the Hindu system of numbers, first to the Arab world and then into Europe. Other great minds included three brothers, the Bani Musa, whose <em>Book of Ingenuous Devices</em> includes a design for a self-playing musical instrument, perhaps the earliest programmable machine. Later Ibn Al Haytham would establish the principle of modern optics, concluding that vision is the result of light bouncing off an object, and that sight is registered in the brain, not the eyes. Other scientific minds named the stars in the sky and invented the syringe and forceps for medicine. The expanded House of Wisdom now included an observatory, the Marsad Falaki. The chief astronomer was Sind ibn Ali, who introduced the decimal point and, with Yaqub ibn Tariq, calculated the Earth’s diameter. Sind ibn Ali was a Jewish convert to Islam. Yaqub ibn Tariq was a Persian. Many Christians also participated in the House of Wisdom. Al Mamun also reached out to the Christian world to expand the House of Wisdom. He acquired the entire book collection of the king of Sicily and asked permission from the Byzantine emperor to translate notable scientific works in his library. Another collection of hand-written manuscripts was said to require 100 camels to transport it to Baghdad. The spread of knowledge was helped by the arrival of paper from China, which replaced parchment. A paper factory was set up in Baghdad, while the dozens of translators working at the House of Wisdom were promised its weight in gold for every book they completed. It was said that one translator made sure to use the thickest paper and write in the biggest letters he could get away with. This vast enterprise was at the centre of the caliphate, preserving and spreading knowledge. Its scholars were responsible for designing buildings and keeping official calendars. They were doctors, engineers and civil servants. As Professor Jim Al-Khalili, the British theoretical physicist, demonstrates, the year 813 and the House of Wisdom was the bridge between the old and the new. His 2010 book <em>House of Wisdom</em> is subtitled <em>How Arabic Science Saved Ancient Knowledge and Gave Us the Renaissance. </em> In 1258, the Mongol army of Genghis Khan swept out of Asia and conquered Baghdad. The city was looted and the House of Wisdom destroyed. So many books were dumped into the Tigris that the water was said to have run black with ink. Now its memory will live again, as the 813 satellite project, whose members include many modern countries that once formed the Abbasid empire, monitors those lands and provides valuable scientific information on the environment and climate. In spirit, as well as name, it reflects the House of Wisdom.