A total solar eclipse occurs when the moon appears as large as or larger than the sun and is positioned exactly in front of the sun, from the perspective of the viewer. As a result, the moon blocks all direct sunlight, turning day into darkness. In addition, the sun and moon maintain this alignment for a period of time, appearing to move together along a path through the sky over long distances.
June 24, 1778 — The first total solar eclipse recorded in the United States was during the American Revolution (the war officially ended on September 3, 1783, with the signing of the Treaty of Paris). General George Washington learned of the upcoming eclipse, in a letter dated January 5, 1777, written by Thomas Wharton (first president of Pennsylvania, an office similar to governor). Wharton warned Washington that “a great Eclipse of the Sun” would soon occur. Wharton suggested that “perhaps it may not be amiss on this occasion to guard against a superstitious fear in the Army which might take place should the Men be unexpectedly surprised with this appearance.”
On January 8, 1777, Washington wrote a letter of thanks to the Pennsylvania Council of Safety for informing him of the impending eclipse. He wrote: “This event, without a previous knowledge of it, might affect the minds of the Soldiery, and be attended with some bad consequences.” Wharton later died in office on May 23, 1778.
Note: Prior to the formal organization of the Supreme Executive Council of the Commonwealth of Pennsylvania in March 1777, executive and military powers were exercised by the Committee of Safety (1775–1776). The Committee was replaced by the Council of Safety (1776–1777), created by the state Constitutional Convention of 1776 to assume executive responsibilities until the new constitutional government could be organized. The Constitution of 1790 provided for a popularly elected governor with expanded executive powers to replace the Supreme Executive Council.
October 27, 1780 — A total solar eclipse occurred on October 27, 1780, also during the American Revolution. A special immunity agreement was negotiated with the British to allow the scientists to work unharmed. Unfortunately, the expedition missed the eclipse because they chose a site on Long Island, which was outside the path of totality. Harvard Professor Samuel Williams was blamed for miscalculating the path of totality. However, he observed a new phenomenon, later named Baily's Beads, which remained a scientific mystery until 1838. This effect occurs when the Moon’s uneven terrain allows sunlight to pass through.
April 14, 1791 (Annular) — The annular solar eclipse of 1791 is notable because the man who predicted it was the country's first African-American mathematician and astronomer, named Benjamin Banneker (1731–1806). Banneker had taught himself, and soon he began publishing an Almanack and Ephemeris, comparable in quality to Benjamin Franklin's almanac. Banneker wrote a long letter to Thomas Jefferson urging the future president to fight for the abolition of slavery. He also included a copy of his meticulous astronomical calculations, and referenced the surveying work he was involved in as a member of a team commissioned by President George Washington to map the District of Columbia. Banneker died on October 9, 1806. During his funeral, his house caught fire, destroying most of his writings and possessions.
June 16, 1806 — The first total solar eclipse of the 1800s, also called “Tecumseh's Eclipse,” in honor of the Shawnee chief, Tecumseh. The path started in Baja California and proceeded to cross over Ohio, Pennsylvania, New York, Vermont, New Hampshire, Massachusetts, Connecticut, and Rhode Island. Salem witnessed the longest duration of daytime darkness, at 4 minutes and 48 seconds.
The term “corona” was first used by Spanish astronomer José Joaquín de Ferrer (1763–1818) to describe the glow surrounding the Sun during the eclipse, as seen from his location in New York. He proposed that the corona must belong to the Sun, because of its great size. Ferrer also observed that, during the eclipse, irregularities of the Moon's surface were plainly discernible.
1824: Discovery of a new method for predicting solar eclipses — The Prussian astronomer and mathematician Friedrich Bessel discovered a new method for predicting solar eclipses by using solar and lunar ephemerides to monitor the Moon's shadow with respect to Earth's center. Changing the frame of reference simplified the mathematics and geometry without sacrificing accuracy, and it continues to be the most accurate technique.
July 18, 1860 — A total eclipse of the sun occurred before the Civil War (April 12, 1861 – April 9, 1865). The eclipse started in the Pacific Ocean, 100 miles west of Oregon. It made landfall at Cape Disappointment in the Pacific Northwest (named by British trader John Meares when he mistakenly believed that the mouth of the Columbia River was only a bay). The eclipse proceeded in a northeasterly direction over the Pacific Northwest, crossing Hudson’s Bay to Cape Chidley in Newfoundland and Labrador (Canada). It then entered the Atlantic Ocean, heading due east towards Cape Farewell, in Greenland, where the sun was totally eclipsed at noon. This eclipse was visible from northern Spain, and traversed across the globe to the Sudan. During this eclipse, the first coronal mass ejection may have been observed as coronal loops.
August 7, 1869 — The total solar eclipse was visible in northeastern Russia, parts of Canada, Alaska and the northern US, from the Montana Territory and moving over several large cities before exiting the country in North Carolina. The New York Sun provided a local account from a New Yorker who witnessed the 87% partial eclipse from Brooklyn Heights. Other reports came from Des Moines, Iowa; Wilmington, North Carolina; and Springfield and Mattoon in Illinois. There was also an account of meteor showers during the eclipse from Shelbyville, Kentucky.
July 29, 1878 — The total solar eclipse was visible across northeastern Asia before it crossed over Alaska, western Canada, and North America from Montana, through Louisiana, and exiting from Texas. It proceeded to cross most of Cuba and southwestern Hispaniola before ending. A team of female astronomers observed the eclipse in Denver, Colorado, and Thomas Edison himself traveled to see the event, bringing scientific equipment to study the sun's corona during the eclipse.