October 29: Richard Hawley Tucker

Richard Hawley Tucker

October 29, 1859 – March 31, 1952

Richard Tucker was an American astronomer.

He was born in Wiscasset, Maine to a ship-owning and sea-faring family. After a brief stint at sea starting at age 14, he attended Lehigh University where he studied civil engineering but became interested in the study of astronomy. He graduated in 1879 and became an assistant at Dudley Observatory. He remained there for four years, and briefly worked with the United States Coast and Geodetic Survey.

In 1883 he joined Lehigh as an instructor of mathematics and astronomy. A year later he was offered a position with the Argentine National Observatory, where he would assist in a survey of the southern night sky. He remained there for nine years, then joined the staff of Lick Observatory in 1893. He remained at Lick until 1908, operating the Meridian Circle program to make precise measurements of star positions.

In 1908 he would travel to San Louis, Argentina as part of an expedition to measure the positions of stars in the southern part of the sky. These measurements were to be incorporated into a catalog for Dudley Observatory. During his time there he made 20,800 observations of stars.

After his work in Argentina, he returned to Lick Observatory. In 1914 he married Ruth Standen, a secretary at Lick. He remained at the observatory until he retired in 1926, when he became Astronomer Emeritus. He spent his retirement years in Palo Alto, California.

During his career he published fifty three scientific articles.

The Lunar crater Tucker is named in his honor.

October 26: Lewis Boss

Lewis Boss

October 26, 1846 - October 12, 1912

Lewis Boss was an American astronomer. He was born in Providence, Rhode Island. In 1870 he graduated from Dartmouth College, then went to work as a clerk for the U.S. Government. He served as an assistant astronomer for a government expedition to survey the U.S-Canadian border. In 1876 he became the director of the Dudley Observatory in Schenectady, New York.

He became editor of the Astronomical Journal in 1909, but responsibility passed to his son, Benjamin Boss, upon his death in 1912. Benjamin continued to edit the journal until 1941.

Lewis Boss is noted for his work in cataloguing the locations and proper motions of stars. He also led an expedition to Chile in 1882 to observe the transit of Venus, and also catalogued information concerning cometary orbits.

In 1910, he published Preliminary General Catalogue of 6188 Stars for the Epoch 1900, a compilation of the proper motions of stars. This catalog was later expanded after his death by his son Benjamin Boss.

His most significant discovery was the calculation of the convergent point of the Hyades star cluster.

Boss was awarded the Gold Medal of the Royal Astronomical Society in 1905.

The Lunar crater Boss is named in his honor.

August 24: Amédée Mouchez

Amédée Ernest Barthélemy Mouchez

August 24, 1821 – June 29, 1892

Amédée Mouchez was a French naval officer who became director of the Paris Observatory and launched the ill-fated Carte du Ciel project in 1887.

Born in Madrid, Spain, Mouchez embarked on a career in the French Navy as an ensign in 1843. This was a period of relative international maritime peace and much of the navy's activities were dedicated to exploration and discovery. Mouchez was initially occupied on hydrographic studies along the coasts of Korea, China and South America, penetrating 320 km up the Paraguay River and exploring the Abrolhos Islands. He improved the practice of surveying at sea, adapting terrestrial instruments for naval use, and was especially concerned with the problems of determining longitude. He developed the use of the theodolite and meridian telescope to improve the error in establishing longitude from around 30″ to 3-4″.

Attaining the rank of post captain in 1868, he embarked on a series of expeditions to chart the coast of Algeria. However, in 1870, during the Franco-Prussian War, he was called upon to make an heroic defence of the port of Le Havre.

Returning to his Algerian survey, he brought it to a conclusion in 1873, when he was elected to the Bureau des Longitudes and, in the following year, was sponsored by the Académie des sciences to observe the transit of Venus from St. Paul Island in the Indian Ocean. On 9 December he made a sequence of superb photographic plates of the event.

In 1875, the Académie elected him a member of the astronomy section and in 1878 he was promoted to rear admiral and awarded the role of director of the Paris Observatory. The observatory had fallen into disrepair and disrepute since the chaos of the 1870 war and the Paris Commune of 1871. Mouchez set about a programme of reconstruction but failed to persuade the government to fund a new observatory outside the centre of Paris.

In 1887, he collaborated with Sir David Gill to host an international astronomical conference in Paris. The principal outcome of the conference was a multi-national project to compile and index a photographic atlas of the heavens, the Carte du Ciel. The project consumed massive effort over several decades before it was rendered obsolete by modern astronomical methods.

The Lunar crater Mouchez is named in his honor.

July 11: Joseph Lalande

Joseph Jérôme Lefrançois de Lalande

July 11, 1732 – April 4, 1807

Joseph Lalande was a French astronomer and writer.

Lalande was born at Bourg-en-Bresse. His parents sent him to Paris to study law, but as a result of lodging in the Hôtel Cluny, where Delisle had his observatory, he was drawn to astronomy, and became the zealous and favoured pupil of both Delisle and Pierre Charles Le Monnier. Having completed his legal studies, he was about to return to Bourg to practise as an advocate, when Lemonnier obtained permission to send him to Berlin, to make observations on the lunar parallax in concert with those of Lacaille at the Cape of Good Hope.

The successful execution of this task obtained for him, before he was twenty-one, admission to the Academy of Berlin, as well as his election as an adjunct astronomer to the French Academy of Sciences. He now devoted himself to the improvement of the planetary theory, publishing in 1759 corrected edition of Edmond Halley's tables, with a history of Halley's Comet whose return in that year he had helped Alexis Clairaut to calculate. In 1762 Delisle resigned the chair of astronomy in the Collège de France in Lalande's favour. The duties were discharged by Lalande for forty-six years. His house became an astronomical seminary, and amongst his pupils were Delambre, Giuseppe Piazzi, Pierre Méchain, and his own nephew Michel Lalande. By his publications in connection with the transit of Venus of 1769 he won great fame. However, his difficult personality lost him some popularity.

Although his investigations were conducted with diligence rather than genius, Lalande's career was an eminent one. As a lecturer and writer he helped popularise astronomy. His planetary tables, into which he introduced corrections for mutual perturbations, were the best available up to the end of the 18th century and the Lalande prize instituted by him in 1802 for the chief astronomical performance of each year still testifies to his enthusiasm for his favourite pursuit.

His star catalog of 1801 contains many faint but nearby (and thereby low mass) stars, so that a star name such as Lalande 21185 is almost guaranteed to refer to such a star, rather than a bluer, brighter, more distant one.

In 1765, Lalande was elected a member of the Royal Swedish Academy of Sciences. The crater Lalande on the Moon is named in his honor.

June 26: Charles Messier

Charles Messier

June 26, 1730 – April 12, 1817

Charles Messier was a French astronomer most notable for publishing an astronomical catalogue consisting of deep sky objects such as nebulae and star clusters that came to be known as the 103 "Messier objects". The purpose of the catalogue was to help comet hunters, as he was, and to help other astronomical observers to distinguish between permanent and transient objects in the sky.

Charles' interest in astronomy was stimulated by the appearance of the spectacular, great six-tailed comet in 1744 and by an annular solar eclipse visible from his hometown on July 25, 1748.

In 1751 he entered the employ of Joseph Nicolas Delisle, the astronomer of the French Navy, who instructed him to keep careful records of his observations. Messier's first documented observation was that of the Mercury transit of May 6, 1753.

In 1764, he was made a fellow of the Royal Society, and on June 30, 1770, he was elected to the French Academy of Sciences. Messier discovered thirteen comets

The first version of Messier's catalogue contained 45 objects and was published in 1774 in the journal of the French Academy of Sciences in Paris. The final version of the catalogue was published in 1781, in Connoissance des Temps for 1784. The final list of Messier objects had grown to 103.

On several different occasions between 1921 and 1966, astronomers and historians discovered evidence of another seven deep-sky objects that were observed either by Messier or his friend and assistant, Pierre Mechain, shortly after the final version was published. These seven objects, M104 through M110, are accepted by astronomers as "official" Messier objects.

The objects' Messier designations, from M1 to M110, still are in use by professional and amateur astronomers today.

The catalogue is not organized scientifically by object type or by location, as the later New General Catalogue would be. Nonetheless, the Messier catalogue comprises examples of every known deep sky object, including galaxies, planetary nebulae, open clusters, and globular clusters. Because these objects were accessible to the relatively small-aperture telescope (approximately 102 mm, or four inches) used by Messier to study the sky, they are among the most spectacular deep sky objects available to modern amateur astronomers using much better equipment. Furthermore, almost all of the Messier objects are among the closest to our planet in their respective classes, which makes them heavily studied with professional class instruments that today, can resolve very small and visually spectacular details in them. Professional astronomers still refer to objects by their Messier designation, and in amateur astronomy they are among the most frequently observed deep sky objects.

Many of the objects in the Messier catalogue were discovered by his assistant, Pierre Mechain.

The crater Messier on the Moon and the asteroid 7359 Messier were named in his honor.

March 23: Norman Robert Pogson

Norman Robert Pogson
March 23, 1829 – June 23, 1891

Norman Robert Pogson was an English astronomer. By the time he was 18 years old, he had computed the orbits of two comets. He became an assistant at Radcliffe Observatory in Oxford, England in 1851. In 1860 he traveled to Madras, India, becoming the government astronomer. At the Madras Observatory he produced the Madras Catalog of 11,015 stars.

In 1861, Pogson was appointed the government astronomer at Madras, India. He was the Director from 1861 to 1891. When he arrived he had to work under harsh conditions. He found the instruments in a bad shape and there were no proper staff to assist him. In spite of all these he began a series of observations which lasted until his death 30 year later. He was credited with 50,000 observations, most of which were published by Michie Smith after Pogson's death. During his stay in Madras he discovered several minor planets and detected large number of variable stars. He named his daughters after the minor planets he discovered. He was also well known for his work in comets and solar eclipses.

His most notable contribution was to note that in the stellar magnitude system introduced by the Greek astronomer Hipparchus, stars of the first magnitude were about a hundred times as bright as stars of the sixth magnitude. His suggestion in 1856 was to make this a standard, so each decrease in magnitude represented a decrease in brightness equal to the fifth-root of 100 (or about 2.512). The Pogson Ratio became the standard method of assigning magnitudes. The magnitude relation is given as follows:

m₂ − m₁ = − 2.5log¹⁰(L₂ / L₁)

where m is the stellar magnitude and L is the luminosity, for stars 1 and 2.

In 1868 and 1871, Pogson joined the Indian solar eclipse expeditions. During his career he discovered a total of eight asteroids and 21 variable stars. He headed the Madras Observatory for 30 years until his death.

The Lunar crater Pogson and asteroid 1830 Pogson are named in his honor.

March 16: Caroline Lucretia Herschel

Caroline Lucretia Herschel

March 16, 1750 – January 9, 1848

Caroline Herschel was a German-born English astronomer, the sister of astronomer Sir William Herschel with whom she worked throughout both of their careers. Her most significant contribution to astronomy was the discovery of several comets and in particular the periodic comet 35P/Herschel-Rigollet, which bears her name.

William's interest in astronomy started as a hobby to pass time at night. He took to retiring to bed as soon as he arrived home, taking "a bason of milk" and an astronomy book for company. At breakfast the next day he would give an impromptu lecture on what he had learned the night before. Caroline became as interested as William, stating that she was "much hindered in my practice by my help being continually wanted in the execution of the various astronomical contrivances." William became known for his work on high performance telescopes, and Caroline found herself supporting his efforts.

William's telescopes gained the attention of many in the field. When comparing observations with the Astronomer Royal, Nevil Maskelyne, William's telescope proved far superior. In March 1781 he made his first observation of what would eventually prove to be the planet Uranus. In 1782, William accepted the office of King's Astronomer to George III and moved to Datchet and subsequently to Observatory House near Slough, Berkshire. The new job proved to be a mixed blessing; although it left him with ample free time to continue his astronomical observations, it also meant a reduction in income and being called upon by the king for entertainment at any time. During this time William perfected his telescope making, building a series of ever larger devices that ultimately ended with his famous 40-foot focal length instrument. Caroline was his constant assistant in his observations, also performing the laborious calculations with which they were connected. During one such observation run on the large telescope in 1783, Caroline became caught on an iron hook and when she was helped off "...they could not lift me without leaving nearly 2 ouches of my flesh behind."

In 1778 William married a rich widow. Although his new wife made every effort to stay on friendly terms with Caroline it seems her life was considerably upset. Through this period she continued her observations on her own, and made many of her discoveries. She later reconciled with the couple, and took great delight in her new nephew, John Herschel.

During her leisure hours she occupied herself with sweeping the heavens with a 27-inch focal length Newtonian telescope and by this means detected a number of astronomical objects during the years 1783 - 87, including most notably an independent discovery of M110 (NGC 205), the second companion of the Andromeda Galaxy. During 1786 - 97 she also discovered eight comets, her first comet being discovered on August 1, 1786. She had unquestioned priority on five of the comets and had rediscovered Comet Encke in 1795. The following year she was granted an annual salary of £50 by George III for her work as William's assistant.

In 1797 William's observations had shown that there were a great many discrepancies in the star catalogue published by John Flamsteed, which was difficult to use due to its having been published as two volumes, the catalogue proper and a volume of original observations. William realised that he needed a proper cross-index in order to properly explore these differences but was reluctant to devote time to it at the expense of his more interesting astronomical activities. He therefore recommended to Caroline that she undertake the task. The resulting Catalogue of Stars was published by the Royal Society in 1798 and contained an index of every observation of every star made by Flamsteed, a list of errata, and a list of more than 560 stars that had not been included.

Caroline returned to Hanover in 1822 following her brother's death, but did not abandon her astronomical studies, continuing to verify and confirm William's findings and producing a catalogue of nebulae to assist John in his work.

In 1828 the Royal Astronomical Society presented her with their Gold Medal for this work - no woman would be awarded it again until Vera Rubin in 1996.

In 1835, along with Mary Somerville, she was elected to honorary membership of the Royal Astronomical Society; they were the first honorary women members. In 1838 she was also elected as a member of the Royal Irish Academy. In 1846 at the age of 96, she was awarded the Gold Medal for Science by the King of Prussia.