The following events occurred in January 1925:

January 1, 1925 (Thursday) Two scientific papers that changed our understanding of the universe were presented on the same day. Cecilia Payne-Gaposchkin completed her Ph.D. thesis, Stellar Atmospheres, described by astronomer Otto Struve as "the most brilliant PhD thesis ever written in astronomy", that led to our understanding that stars are primarily composed of hydrogen and helium, rather than heavier elements as previously thought." On the same day, at Corcoran Hall of George Washington University, astronomer Edwin Hubble presented to a New Year's Day meeting of the American Astronomical Society, his paper Cepheids in Spiral Nebulae, an analysis of the relation between the distance of remote galaxies and their relative velocity that showed the expansion of the Universe. Norway's capital, Christiania, was renamed Oslo. In the Rose Bowl, the unbeaten and untied (9–0–0) Notre Dame Fighting Irish defeated the unbeaten (7–0–1) Stanford University Indians, 27 to 10, before a crowd of 60,000 people in Pasadena. On the same day, the unbeaten (8–0–1) Penn Quakers visited the unbeaten (7–0–2) California Golden Bears in a postseason game at Berkeley, with California winning, 14 to 0, before 60,000 people. On November 22, Stanford and California had played to a 20–20 tie. Later in the year, economics professor Frank G. Dickinson of the University of Illinois ranked Notre Dame the best team of the 1924 season, followed by California as part of his "Dickinson ratings" that would later be recognized by the NCAA as determinative of a college football national champion. A small contingent of U.S. Marines arrived at Nanjing to patrol the vicinity of the university and protect Americans there from further looting. Costa Rica decided to withdraw from the League of Nations over the League's failure to address regional disputes. The states of Aleppo and Damascus were united into the State of Syria. Born: Paul Bomani, Tanzanian politician and ambassador; in Musoma, Tanganyika Territory (present-day Tanzania) (d. 2005)

January 2, 1925 (Friday) Fresh violence broke out around Italy as Benito Mussolini's crackdown on opposition newspapers continued. Fascists seized or attacked newspaper presses while at least three were killed in rioting. Mussolini met with King Victor Emmanuel III and requested dictatorial powers to quell the chaos. The king refused, but gave Mussolini tacit permission to act however he considered necessary within at least the appearance of constitutional legality. Leo Chiozza Money testified before Britain's Royal Commission that an increase in the world's population had led to the country's food situation becoming as desperate as it was during the war. "The 10 pence price of bread has doubled in recent years and looking into the future there are good prospects of its doubling again", he stated. Money recommended a "department of supply" be created to remedy the problem. Born: Giacomo Furia, Italian actor; in Arienzo, Kingdom of Italy (present-day Italy) (d. 2015) Larry Harmon, American entertainer known for portraying Bozo the Clown; as Lawrence Weiss, in Toledo, Ohio, United States (d. 2008) Eraño de Guzman Manalo, Philippine cleric and second Executive Minister (Tagapamahalang Pangkalahatan) of the Iglesia ni Cristo (Church of Christ); in San Juan City, Philippine Islands (present-day Philippines) (d. 2009) Died: Nikola Petroff, 51, Bulgarian wrestler (b. 1873)

January 3, 1925 (Saturday) Benito Mussolini made a pivotal speech in the Italian Chamber of Deputies and responded to the Matteotti Crisis. He took personal responsibility for the actions of his Blackshirts, challenged his political opponents to remove him from office and then promised to take charge of restoring order to Italy within forty-eight hours. Historians now trace this speech to the beginning of Mussolini's dictatorship. Cyril Brownlie was sent off the field for foul play during a rough Test match against England during New Zealand's 1924–25 rugby union tour of Britain, Ireland and France. It was the first time such a severe sanction had ever been applied in an international rugby match. New Zealand won 17-11. In a matchup of two of the best teams of the 1924–25 NCAA men's basketball season, the visiting Princeton Tigers of the Ivy League (officially, the Eastern Intercollegiate League) defeated the Ohio State Buckeyes of the Big Ten Conference, 39 to 34, after trailing 15 to 22 at halftime. Both teams would win finish with only two losses and become champions of their conferences, with Ohio State at 14 wins and 2 losses. Princeton would finish with a record of 21 wins and 2 losses, and be retroactively selected by historians as the best team of the 1924–1925 season.

January 4, 1925 (Sunday) Prefects throughout Italy received orders to control all "suspect" political organizations. Over the next two days, hundreds of private homes were searched, meeting halls were closed, political groups were disbanded and newspapers were seized. Adolf Hitler, whose Nazi Party had been banned in Bavaria since the failed Beer Hall Putsch, met with the state's Minister President Heinrich Held. Hitler pledged total loyalty to Held and offered to help him in his fight against communists. Born: Veikko Hakulinen, Finnish cross-country skier and gold medalist in three consecutive Winter Olympics games; in Kurkijoki, Karelian ASSR (present-day Finland) (d. 2003) Died: Nellie Cashman, 79, Irish-born prospector (b. 1845)

January 5, 1925 (Monday) Nellie Tayloe Ross became the first woman to be elected as the governor of a U.S. state as she was inaugurated as Governor of Wyoming. Ross had won a special election on November 3 to fill the remainder of the term of her late husband, Governor William B. Ross, who had died on October 2. Mrs. Ross succeeded Frank Lucas, who had served as acting Governor upon Mr. Ross's death. The only two Italian Liberal Party ministers in Benito Mussolini's cabinet, Gino Sarrocchi and Alessandro Casati, turned in their resignations. They were to be replaced by loyal Fascists, who were now the only party in Mussolini's cabinet. The stage comedy Is Zat So?, later to be made into a silent film, began the first of 634 performances on Broadway, making its debut at the 39th Street Theatre before moving to Chanin's 46th Street Theatre. Later in the year, a second production would open on London's West End at the Adelphi Theatre. The play was co-authored by James Gleason (who oversaw the West End run) and Richard Taber (who stayed at Broadway).

January 6, 1925 (Tuesday) At the Finnish-American A.C. Games held at Madison Square Garden, Finnish runner Paavo Nurmi set two new indoor records in front of a standing-room only crowd. Born: John DeLorean, American car manufacturer; in Detroit (d. 2005)

January 7, 1925 (Wednesday) The new Al Jolson stage show Big Boy opened at the Winter Garden Theatre on Broadway. The German cruiser was launched, the first large warship built in Germany since the end of the war. Born: Gerald Durrell, English naturalist, zookeeper, author, and television presenter; in Jamshedpur, Central Provinces, British India (present-day Jharkhand state, India) (d. 1995)

January 8, 1925 (Thursday) In Italy, A joint manifesto signed by the leaders of the parties "on the Aventine" condemned Mussolini's suppression of dissent, writing, "The whole country can bear witness to the fact that the pretext of this policy is a ridiculous lie as no conspiracy is threatening the country and no attempt has been made against the laws." The manifesto suggested that Mussolini resign. In India, Bhanupratap Deo, the 3-year-old son of the late Lal Kamal Deo, was proclaimed as the new Raja of the Kanker State, a princely state within British India, and now part of the state of Chhattisgarh. He would rule until 1947, upon the independence of India and the abolition of princely states. Born: Helmuth Hübener, German anti-Nazi youth activist; in Hamburg, Germany (d. 1942, executed) Mohan Rakesh, Indian playwright and the author of Ashadh Ka Ek Din, the first modern Hindi language play; as Madan Mohan Guglani, in Amritsar, Punjab Province, British India (present-day Punjab state, India) (d. 1972) Died: George Bellows, 42, American artist; died of peritonitis following a ruptured appendix (b. 1882) Leo Koretz, 45, American lawyer and con man who masterminded the "Bayano Oil fraud", a Ponzi scheme that gathered $30 million from investors for false claims of oil fields; died in the Illinois State Penitentiary from diabetes (b. 1879)

January 9, 1925 (Friday) British economist George Paish said that another war in Europe was inevitable unless Germany's reparations payments were reduced and the French were to leave the Rhineland. He also warned that "Germany will not make the mistake she made the last time, in having Russia as an enemy, but will have that nation as a friend. Germany and Russia will be able to overrun Europe and establish a military despotism." Born: Lee Van Cleef, American film actor; as Clarence LeRoy Van Cleef Jr., in Somerville, New Jersey, United States (d. 1989)

January 10, 1925 (Saturday) The British submarine HMS L24 sank in the English Channel after colliding with the Royal Navy battleship HMS Resolution. All 43 men on L24 died. The Ku Klux Klan was banned from the state of Kansas when its Supreme Court ruled that it was a corporation organized for profit and therefore could not operate there without a charter. A clause in the Treaty of Versailles (articles 276 and 280), requiring Germany to grant most favored nation trade status with the former World War One allies, expired and allowed the Germans to negotiate their own economic ties. The deadline for the Allies to cease their occupation of the Germany's Rhineland passed without the withdrawal of French and Belgian forces. The government of France declared that the refusal was justified by "breaches of the disarmament clauses" of the Versailles Treaty.

January 11, 1925 (Sunday) Beijing was seized by the combined forces of Sun Chuanfang and Qi Xieyuan. The Chinese Communist Party opened its Fourth Congress in Shanghai. Born: Grant Tinker, American television executive, co-founder of MTM Enterprises and creator of The Mary Tyler Moore Show; in Stamford, Connecticut, United States (d. 2016)

January 12, 1925 (Monday) In Chicago, the North Side Gang tried to kill Al Capone, using Tommy guns to rake his car with bullets as it idled outside a State Street restaurant. Only Capone's bodyguard was wounded as Capone himself was doing business inside, but the attack prompted him to order Tommy guns for his own men, as well as his famous bulletproof Cadillac. The John Howard Lawson play Processional: A Jazz Symphony of American Life opened at the Garrick Theatre in New York.

January 13, 1925 (Tuesday) A train crash in Westphalia in Germany killed 25 people and injured 60 others. Born: Georgi Kaloyanchev, Bulgarian actor; in Burgas, Bulgaria (d. 2012) Gwen Verdon, American actress and dancer; as Gwyneth Verdon, in Culver City, California, United States (d. 2000)

January 14, 1925 (Wednesday) The Agreement Regarding the Distribution of the Dawes Annuities was signed in Paris among the Entente Powers, apportioning the distribution of the Central Powers' reparations payments, including those of Germany under the Dawes Plan, among the various countries that were entitled to the payments. Born: Yukio Mishima, Japanese writer; as Kimitake Hiraoka, in Shinjuku, Tokyo, Empire of Japan (present-day Japan) (d. 1970) Died: Camille Decoppet, 62, Swiss politician, served as a Federal Councilor from 1912 to 1919 (b. 1862) Harry Furniss, 70, English cartoonist, illustrator and animation pioneer (b. 1854)

January 15, 1925 (Thursday)