|Ab urbe condita||2462|
|Balinese saka calendar||1630–1631|
|British Regnal year||7 Ann. 1 – 8 Ann. 1|
|Chinese calendar||戊子年 (Earth Rat)|
4405 or 4345
— to —
己丑年 (Earth Ox)
4406 or 4346
|- Vikram Samvat||1765–1766|
|- Shaka Samvat||1630–1631|
|- Kali Yuga||4809–4810|
|Japanese calendar||Hōei 6|
|Julian calendar||Gregorian minus 11 days|
|Minguo calendar||203 before ROC|
|Thai solar calendar||2251–2252|
1835 or 1454 or 682
— to —
1836 or 1455 or 683
|Wikimedia Commons has media related to 1709.|
1709 (MDCCIX) was a common year starting on Tuesday of the Gregorian calendar and a common year starting on Saturday of the Julian calendar, the 1709th year of the Common Era (CE) and Anno Domini (AD) designations, the 709th year of the 2nd millennium, the 9th year of the 18th century, and the 10th and last year of the 1700s decade. As of the start of 1709, the Gregorian calendar was 11 days ahead of the Julian calendar, which remained in localized use until 1923. In the Swedish calendar it was a common year starting on Friday, one day ahead of the Julian and ten days behind the Gregorian calendar.
- January 6 – Western Europe's Great Frost of 1709, the coldest period in 500 years, begins during the night, lasting three months, with its effects felt for the entire year. In France, the Atlantic coast and Seine River freeze, crops fail, and 24,000 Parisians die. Floating ice enters the North Sea.
- January 10 – Abraham Darby I successfully produces cast iron, using coke fuel at his Coalbrookdale blast furnace in Shropshire, England.
- February – In America, Mardi Gras is celebrated one more time with Masque de la Mobile in the capital of French Louisiana, Mobile, Alabama, before Mobile is moved 27 miles (43 km) down the Mobile River to Mobile Bay, in 1711.
- February 1 or 2 – During his first voyage, Captain Woodes Rogers encounters marooned privateer Alexander Selkirk, and rescues him after four years living on one of the Juan Fernández Islands, inspiring Daniel Defoe's novel Robinson Crusoe. After sacking Guayaquil, he and Selkirk will visit the Galápagos Islands.
- March 28 – Johann Friedrich Böttger reports the first production of hard-paste porcelain in Europe, at Dresden.
- May – The first influx into Britain of poor refugee families of German Palatines from the Rhenish Palatinate arrives, mostly Protestants en route to the New World colonies.
- June 27 (June 28 in the Swedish calendar; July 8 New Style) – Great Northern War – Battle of Poltava: In the Ukraine, Peter the Great, Tsar of Russia, defeats Charles XII of Sweden, thus effectively ending Sweden's role as a major power in Europe.
- July 27 – Emperor Nakamikado accedes to the throne of Japan.
- July 30 – War of the Spanish Succession: Tournai is captured by John Churchill, 1st Duke of Marlborough and Prince Eugene of Savoy.
- August 8 – The hot air balloon of Bartolomeu de Gusmão flies in Portugal.
- August 28 – Pamheiba is crowned King of Manipur.
- September 11 (August 31 Old Style) – War of the Spanish Succession – Battle of Malplaquet: Troops of the Dutch Republic, Habsburg Austria, the Kingdom of Great Britain and the Kingdom of Prussia, led by the Duke of Marlborough, drive the French from the field, but suffer twice as many casualties.
- October 9 – War of the Spanish Succession: The British army captures Mons.
- October 12 – The city of Chihuahua, Mexico is founded.
- December 25 – From London, ten ships leave for the New York Colony, carrying over 4,000 people.
- Trinity School is founded as the Charity School of Trinity Church, in New York City.
- The second Eddystone Lighthouse, erected off the south west coast of England by John Rudyerd, is completed.
- The first modern edition of William Shakespeare's plays is published in London, edited by Nicholas Rowe.
- De Nostri Temporis Studiorum Rationae (On the Study Methods of Our Times) is published by Neapolitan philosopher Giambattista Vico.
- Priceless medieval altarpieces, created by Tyrolese sculptor Michael Pacher, are destroyed.
- January 2 – Teresia Constantia Phillips, British autobiographer (d. 1765)
- February 16 – Henrika Juliana von Liewen, Swedish political salonniére (d. 1779)
- February 24 – Jacques de Vaucanson, French inventor (d. 1782)
- March 10 – Georg Steller, German naturalist (d. 1746)
- April 14 – Charles Collé, French dramatist (d. 1783)
- August 10 – Jean-Jacques Lefranc, Marquis de Pompignan, French polymath, author and poet (d. 1784)
- August 8 – Tokugawa Ietsugu, 7th Tokugawa shogunate of Japan (d. 1716)
- September 18 – Samuel Johnson, English writer, critic and lexicographer (d. 1784)
- September 24 (bapt.) – John Cleland, English novelist (d. 1789)
- October 27 (bapt.) – Thomas Alcock, English clergyman (d. 1798)
- November 2 – Anne, Princess Royal and Princess of Orange, Hanoverian-born regent of Friesland (d. 1759)
- December 18 – Elizabeth of Russia, empress regnant of Russia (d. 1762)
- January 16 – Emperor Higashiyama of Japan (b. 1675)
- January 20 – François de la Chaise, French confessor of Louis XIV of France (b. 1624)
- January 22 – Henry Herbert, 1st Baron Herbert of Chirbury, English politician (b. 1654)
- January 24 – George Rooke, English admiral (b. 1650)
- January 26 – Eleonore Charlotte of Saxe-Lauenburg-Franzhagen, Duchess of Schleswig-Holstein-Sonderburg-Franzhagen (b. 1646)
- February 8 – Giuseppe Torelli, Italian composer (b. 1658)
- February 9 – François Louis, Prince of Conti, French general (b. 1664)
- February 11 – Louise Hollandine of the Palatinate, German artist (b. 1622)
- February 17 – Erik Benzelius the Elder, Swedish theologian (b. 1632)
- February 19 – Tokugawa Tsunayoshi, Japanese shōgun (b. 1646)
- March 9 – Ralph Montagu, 1st Duke of Montagu, English diplomat
- March 21 – Burchard de Volder, Dutch mathematician (b. 1643)
- April 1 – Henri Jules, Prince of Condé (b. 1643)
- April 2 – Giovanni Battista Gaulli, Italian artist working in the High Baroque and early Rococo periods (b. 1639)
- April 5 – Roger de Piles, French painter (b. 1635)
- April 8 – Wolfgang Dietrich of Castell-Remlingen, German nobleman (b. 1641)
- April 20 – Johann Ernst von Thun, Tyrolean Catholic bishop (b. 1643)
- April 21
- June 25 – Frederick VII, Margrave of Baden-Durlach from 1677 until his death (b. 1647)
- June 29 – Antoine Thomas, Belgian Jesuit astronomer in China (b. 1644)
- June 30 – Edward Lhuyd, Welsh scientist (b. 1660)
- July 17 – Robert Bolling, English settler in Virginia (b. 1646)
- August 24 – Elisabeth Dorothea of Saxe-Gotha-Altenburg, German princess (b. 1640)
- August 31 – Andrea Pozzo, Jesuit Brother, architect and painter (b. 1642)
- September 4 – Jean-François Regnard, French comic poet (b. 1655)
- September 7 – Gunno Dahlstierna, Swedish poet (b. 1661)
- September 14 – Luis Manuel Fernández de Portocarrero, Spanish cardinal and archbishop of Toledo (b. 1635)
- October 2 – Ivan Mazepa, Hetman of Ukraine (b. 1639)
- October 5 – Daniel Speer, German Baroque composer and writer (b. 1636)
- October 9 – Barbara Palmer, 1st Duchess of Cleveland, English mistress of Charles II of England (b. 1640)
- October 31 – Henry Hyde, 2nd Earl of Clarendon, English nobleman (b. 1638)
- November 4 – Barend Graat, Dutch painter (b. 1628)
- November 23 – William Bentinck, 1st Earl of Portland (b. 1649)
- November 29 – Charles Dormer, 2nd Earl of Carnarvon, English noble (b. 1632)
- December 1 – Abraham a Sancta Clara, Austrian preacher (b. 1644)
- December 7 – Meindert Hobbema, Dutch painter (b. 1638)
- December 8 – Thomas Corneille, French dramatist (b. 1625)
- December 15 – Sir Stephen Lennard, 2nd Baronet, English politician (b. 1637)
- December 31
- date unknown – John Coode, Colonial governor of Maryland (d. 1648)
- probable date – Eleanor Glanville, English entomologist (b. 1654)
- Pain, Stephanie. "1709: The year that Europe froze." New Scientist, 7 February 2009.
- Mott, R. A. (January 5, 1957). "The earliest use of coke for ironmaking". The Gas World, coking section supplement. 145: 7–18.
- Raistrick, Arthur (1953). Dynasty of Ironfounders: the Darbys and Coalbrookdale. London: Longmans, Green. p. 34.
- Williams, Hywel (2005). Cassell's Chronology of World History. London: Weidenfeld & Nicolson. p. 292. ISBN 0-304-35730-8.
- Penguin Pocket On This Day. Penguin Reference Library. 2006. ISBN 0-14-102715-0.
- Ober, Frederick A. (1912). Our West Indian Neighbors: the Islands of the Caribbean Sea. New York: James Pott & Company. p. 11.
- Jackson, Michael H. (1993). Galapagos: a Natural History. University of Calgary Press. ISBN 1-895176-07-7.
- Gardiner, Juliet (1995). Wenborn, Neil (ed.). The History Today Companion to British History. London: Collins & Brown. p. 577. ISBN 1-85585-178-4.
- Palmer, Alan; Veronica (1992). The Chronology of British History. London: Century Ltd. pp. 207–208. ISBN 0-7126-5616-2.
- Majdalany, Fred (1959). The Red Rocks of Eddystone. London: Longmans. p. 86.