The Great Comet of 1819, officially designated as C/1819 N1, also known as Comet Tralles, was an exceptionally bright and easily visible

comet A comet is an icy, small Solar System body that, when passing close to the Sun, warms and begins to release gases, a process that is called outgassing. This produces a visible atmosphere or coma, and sometimes also a tail. These phenomena ...

, approaching an

apparent magnitude Apparent magnitude () is a measure of the brightness of a star or other astronomical object observed from Earth. An object's apparent magnitude depends on its intrinsic luminosity, its distance from Earth, and any extinction of the object's ...

of 1–2, discovered July 1, 1819 by the German astronomer

Johann Georg Tralles Johann Georg Tralles (15 October 1763 – 19 November 1822) was a German mathematician and physicist. He was born in Hamburg, Germany and was educated at the Georg August University of Göttingen, University of Göttingen beginning in 1783. H ...

Berlin Berlin ( , ) is the capital and List of cities in Germany by population, largest city of Germany by both area and population. Its 3.7 million inhabitants make it the European Union's List of cities in the European Union by population within ci ...

. It was the first comet analyzed using

polarimetry Polarimetry is the measurement and interpretation of the polarization of transverse waves, most notably electromagnetic waves, such as radio or light waves. Typically polarimetry is done on electromagnetic waves that have traveled through or ...

, by French mathematician François Arago.

Discovery

On July 1, 1819,

in Berlin observed a brilliant comet low in the sky during the evening

twilight Twilight is light produced by sunlight scattering in the upper atmosphere, when the Sun is below the horizon, which illuminates the lower atmosphere and the Earth's surface. The word twilight can also refer to the periods of time when this i ...

. It was confirmed the next night by the

astronomer An astronomer is a scientist in the field of astronomy who focuses their studies on a specific question or field outside the scope of Earth. They observe astronomical objects such as stars, planets, moons, comets and galaxies – in either ...

Johann Elert Bode Johann Elert Bode (; 19 January 1747 – 23 November 1826) was a German astronomer known for his reformulation and popularisation of the Titius–Bode law. Bode determined the orbit of Uranus and suggested the planet's name. Life and career B ...

, also in Berlin.

Observations

On July 2, Tralles found the comet to have a coma of 40″. On July 3,

Friedrich Georg Wilhelm von Struve Friedrich Georg Wilhelm von Struve (russian: link=no, Василий Яковлевич Струве, trans. ''Vasily Yakovlevich Struve''; 15 April 1793 – ) was a Baltic German astronomer and geodesist from the famous Struve family. He is be ...

measured the

nucleus Nucleus ( : nuclei) is a Latin word for the seed inside a fruit. It most often refers to: *Atomic nucleus, the very dense central region of an atom * Cell nucleus, a central organelle of a eukaryotic cell, containing most of the cell's DNA Nucl ...

at 8″ with a

tail The tail is the section at the rear end of certain kinds of animals’ bodies; in general, the term refers to a distinct, flexible appendage to the torso. It is the part of the body that corresponds roughly to the sacrum and coccyx in mammal ...

of several degrees.

Heinrich Wilhelm Matthias Olbers Heinrich Wilhelm Matthias Olbers (; ; 11 October 1758 – 2 March 1840) was a German physician and astronomer. Life and career Olbers was born in Arbergen, Germany, today part of Bremen, and studied to be a physician at Göttingen (1777–80 ...

reported that the nucleus had an apparent magnitude of 1–2 and a tail about 7–8° long. The comet was last sighted by Struve on October 25. Also on July 3, François Arago used a polarimeter of his own invention to analyze the light from the comet's tail and discovered that it was polarized. He then observed the nearest star,

Capella Capella is the brightest star in the northern constellation of Auriga. It has the Bayer designation α Aurigae, which is Latinised to Alpha Aurigae and abbreviated Alpha Aur or α Aur. Capella is the sixth-brightest star in ...

, which did not show polarized light. This indicated that some light from the comet's tail was reflected from the sun. This marked the first

polarimetric Polarimetry is the measurement and interpretation of the polarization of transverse waves, most notably electromagnetic waves, such as radio or light waves. Typically polarimetry is done on electromagnetic waves that have traveled through or ...

observation of a comet.

Transit of the Sun

After the orbital elements of the comet were calculated by Olbers, he discovered that a transit of the Sun by the comet had occurred on June 26, days before its first observations. He reported this to Bode on July 27.

Orbit

Orbital elements for the comet were calculated by several astronomers. The orbit is classified as parabolic and is nearly perpendicular to Earth's orbital plane, with an

inclination Orbital inclination measures the tilt of an object's orbit around a celestial body. It is expressed as the angle between a reference plane and the orbital plane or axis of direction of the orbiting object. For a satellite orbiting the Eart ...

of 80°. It passed closest to the Earth on June 25 at a distance of and closest to the Sun on June 28 at . The orbit of the comet and its transit of the Sun were later analyzed by astronomer John Russell Hind. In 2016 the orbit was recalculated based on a total of 692 observations of the comet taken in 1819, with the resulting conclusion that the comet will not return for over 3,000 years and represents no threat to the Earth, and that Near Eastern records around 2550 BCE may be found to mention its earlier passage.

In literature

The comet was widely seen and noted by people who were not astronomers. Poet John Keats noted how he and his wife Fanny had stared at the comet. Historian Nathaniel Philbrick writes about the great comet seen in July 1819 by the people on the island of Nantucket,

Massachusetts Massachusetts (Massachusett: ''Muhsachuweesut Massachusett_writing_systems.html" ;"title="nowiki/> məhswatʃəwiːsət.html" ;"title="Massachusett writing systems">məhswatʃəwiːsət">Massachusett writing systems">məhswatʃəwiːsət'' En ...

in his 2000 book, '' In the Heart of the Sea''. The comet was observed by the Stephen Long expedition to the Great Plains from near present day Jefferson City, Missouri.

References

External links

JPL DASTCOM Orbital Elements
* {{DEFAULTSORT:1819

1819 Events January–March * January 2 – The Panic of 1819, the first major peacetime financial crisis in the United States, begins. * January 25 – Thomas Jefferson founds the University of Virginia. * January 29 – Si ...

Astronomical objects discovered in 1819 Great comets