About September 23

September 23, 2025 is the 266th day of the year 2025 in the Gregorian calendar. There are 99 days remaining until the end of this year. The day of the week is Tuesday.

You can browse the full year calendar in case you need it.

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Virgo is the sun sign of a person born on this day. Sapphire is the modern birthstone for this month. Agate is the mystical birthstone from Tibetan origin that dates back over a thousand years.

According to the lunisolar Chinese calendar, there are 147 days remaining before the start of the next Chinese New Year.

September 23: More About This Day

It is frequently the day of the Autumnal Equinox in the Northern Hemisphere and the day of the Vernal Equinox in the Southern Hemisphere.

What Happened On September 23

  • 1779
    American Revolution: a squadron commanded by John Paul Jones on board the USS Bonhomme Richard wins the Battle of Flamborough Head, off the coast of England, against two British warships.
  • 1780
    American Revolution: British Major John André is arrested as a spy by American soldiers exposing Benedict Arnold’s change of sides.
  • 1821
    Tripolitsa, Greece, falls and 30,000 Turks are massacred during the Greek War of Independence.
  • 1857
    The Russian warship Lefort capsizes and sinks during a storm in the Gulf of Finland, killing all 826 aboard.
  • 1868
    Grito de Lares (“Lares Revolt”) occurs in Puerto Rico against Spanish rule.
  • 1889
    Nintendo Koppai (Later Nintendo Company, Limited) is founded by Fusajiro Yamauchi to produce and market the playing card game Hanafuda.
  • 1905
    Norway and Sweden sign the “Karlstad treaty”, peacefully dissolving the Union between the two countries.
  • 1908
    University of Alberta in Alberta, Canada, is founded.
  • 1909
    The Phantom of the Opera (original title: Le Fantôme de l'Opéra), a novel by French writer Gaston Leroux, is first published as a serialization in Le Gaulois.
  • 1936
    First ascent of Siniolchu by a German team.
  • 1941
    World War II: The first gas chamber experiments are conducted at Auschwitz.
  • 1942
    World War II: First day of the September Matanikau action on Guadalcanal as United States Marine Corps forces attack Imperial Japanese Army units along the Matanikau River.
  • 1943
    World War II: The Nazi puppet state the Italian Social Republic is founded.
  • 1952
    Richard Nixon makes his “Checkers speech”.
  • 1969
    The Chicago Eight trial opens in Chicago.
  • 1973
    Juan Perón returns to power in Argentina.
  • 1983
    Gulf Air Flight 771 is bombed, killing all 117 people on board.
  • 1983
    Saint Kitts and Nevis joins the United Nations.
  • 1999
    NASA announces that it has lost contact with the Mars Climate Orbiter.
  • 2008
    Kauhajoki school shooting: Matti Saari kills 10 people before committing suicide.

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