Samuel Heinrich Schwabe (25 October 1789 – 11 April 1875) a German

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 ...

remembered for his work on sunspots. Schwabe was born at Dessau. At first an

apothecary ''Apothecary'' () is a mostly archaic term for a medical professional who formulates and dispenses '' materia medica'' (medicine) to physicians, surgeons, and patients. The modern chemist (British English) or pharmacist (British and North Amer ...

, he turned his attention to

astronomy Astronomy () is a natural science that studies celestial objects and phenomena. It uses mathematics, physics, and chemistry in order to explain their origin and evolution. Objects of interest include planets, moons, stars, nebulae, g ...

, and in 1826 commenced his observations on sunspots. Schwabe was looking for a possible planet inside the

orbit In celestial mechanics, an orbit is the curved trajectory of an object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an artificial satellite around an object or position in space such as ...

of Mercury. Because of the proximity to the

Sun The Sun is the star at the center of the Solar System. It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core. The Sun radiates this energy mainly as light, ultraviolet, and infrared radi ...

, it would have been very difficult to observe such a planet, and Schwabe believed one possibility to detect a new planet might be to see it as a dark spot when passing in front of the Sun. For 17 years, from 1826 to 1843, on every clear day, Schwabe would scan the Sun and record its spots trying to detect any new planet among them. He did not find any planet but noticed the regular variation in the number of sunspots and published his findings in a short article entitled "Solar Observations during 1843". In it he made the suggestion of a probable ten-year

period Period may refer to: Common uses * Era, a length or span of time * Full stop (or period), a punctuation mark Arts, entertainment, and media * Period (music), a concept in musical composition * Periodic sentence (or rhetorical period), a concept ...

(i.e. that at every tenth year the number of spots reached a maximum). This paper at first attracted little attention, but

Rudolf Wolf Johann Rudolf Wolf (7 July 1816 – 6 December 1893) was a Swiss astronomer and mathematician best known for his research on sunspots. Wolf was born in Fällanden, near Zurich. He studied at the universities of Zurich, Vienna, and Berlin. Encke ...

who was at that time the director of Bern observatory, was impressed so he began regular observations of sunspots. Schwabe's observations were afterwards utilized in 1850 by

Alexander von Humboldt Friedrich Wilhelm Heinrich Alexander von Humboldt (14 September 17696 May 1859) was a German polymath, geographer, naturalist, explorer, and proponent of Romantic philosophy and science. He was the younger brother of the Prussian minister, ...

in the third volume of his '' Kosmos''. From pp. 401–402: ''"Die in der nachfolgenden Tabelle enthaltenen Zahlen lassen wohl keinen Zweifel übrig, daß wenigstens vom Jahre 1826 bis 1850 eine Periode der Sonnenflecken von ohngefähr 10 Jahren in der Art statt gefunden hat: … "'' (The numbers contained in the following table leave no doubt that at least from the year 1826 to 1850, a period for sunspots of about 10 years or so has occurred: … )
* English translation: From p. 85: "The numbers contained in the following table leave no doubt that, at least from the year 1826 to 1850, the occurrence of unspots has been so far characterized by periods of ten years, … " The periodicity of sunspots is now fully recognized; and to Schwabe is thus due the credit of one of the most important discoveries in astronomy. In 1857 Schwabe was awarded the

Gold Medal of the Royal Astronomical Society The Gold Medal of the Royal Astronomical Society is the highest award given by the Royal Astronomical Society (RAS). The RAS Council have "complete freedom as to the grounds on which it is awarded" and it can be awarded for any reason. Past awar ...

References

External links

*Excerpts from Solar Observations During 1843 by Heinrich Schwab

*Address delivered by the President of the RAS on presenting the Gold Medal of the Society to M. Schwab

*HAO "S. Heinrich Schwabe (1789-1875)

*HAO "S. Heinrich Schwabe (1789-1875)

with portrait. *Chris Plicht "Schwabe, Samuel Heinrich (1789 - 1875)

*The Sun—Histor

{{DEFAULTSORT:Schwabe, Heinrich 1789 births 1875 deaths People from Dessau-Roßlau 19th-century German astronomers Recipients of the Gold Medal of the Royal Astronomical Society Foreign Members of the Royal Society