Short answers, pulled from the story.
Mongkut, also known as Rama IV, was king of Siam from 1851 until his death on the 1st of October 1868. He was born on the 18th of October 1804 and is posthumously honored as King Mongkut the Great and as the Father of Science and Technology in Siam.
Mongkut accurately predicted the total solar eclipse of the 18th of August 1868, calculating that it would be best viewed from Wakor village in Prachuap Khiri Khan Province at longitude 99 degrees 42' east of Greenwich and latitude 11 degrees 39' north. He invited senior Siamese and European officials, including Sir Harry Ord, the British governor of the Straits Settlements, to witness it.
The Bowring Treaty was a trade agreement negotiated in 1854 between Siam and John Bowring, governor of Hong Kong on behalf of Queen Victoria. It abolished the Royal Storage, the monopoly controlling foreign trade since the Ayutthaya period, and reduced import taxation to 3 percent collected only once. The treaty opened Siam to free trade, spurred rice farming and early industries like rice milling and sugar production, and led to the introduction of coinage in 1860.
Anna Leonowens was an English teacher hired by Mongkut's court in 1862 on the recommendation of Tan Kim Ching in Singapore. Her memoir, "The English Governess at the Siamese Court," written around 1870, became the basis for Margaret Langdon's 1944 book "Anna and the King of Siam" and ultimately for the Rodgers and Hammerstein musical "The King and I" and its 1956 film adaptation, which Thailand banned as lese-majeste.
Mongkut founded the Dhammayuttika Nikaya, known as the Dhammayut sect, in 1835 from within his monastic life. It emphasized strict adherence to the vinaya, the code of monastic discipline. His son Chulalongkorn granted the sect formal royal recognition in 1902 through the Ecclesiastical Polity Act, and it became one of the two major Buddhist denominations in modern Thailand.
Three engineering universities, collectively called the Three Phra Chom, bear Mongkut's name: King Mongkut's Institute of Technology Ladkrabang, King Mongkut's University of Technology Thonburi, and King Mongkut's University of Technology North Bangkok. The asteroid 151834 Mongkut was named in his honor for his contributions to astronomy and to the modernization of Siam.