July 31: Friedrich Robert Helmert

Friedrich Robert Helmert

July 31, 1843 – June 15, 1917

Friedrich Robert Helmert was a German geodesist and an important writer on the theory of errors.

Helmert was born in Freiberg, Kingdom of Saxony. After schooling in Freiberg and Dresden, he entered the Polytechnische Schule, now Technische Universität, in Dresden to study engineering science in 1859. Finding him especially enthusiastic about geodesy, one of his teachers, August Nagel, hired him while still a student to work on the triangulation of the Erzgebirge and the drafting of the trigonometric network for Saxony. In 1863 Helmert became Nagel's assistant on the Central European Arc Measurement. After a year's study of mathematics and astronomy Helmert obtained his doctor's degree from the University of Leipzig in 1867 for a thesis based on his work for Nagel.

In 1870 Helmert became instructor and in 1872 professor at RWTH Aachen, the new Technical University in Aachen. At Aachen he wrote Die mathematischen und physikalischen Theorien der höheren Geodäsie (Part I was published in 1880 and Part II in 1884). This work laid the foundations of modern geodesy.

The method of least squares had been introduced into geodesy by Gauss and Helmert wrote a fine book on least squares (1872, with a second edition in 1907) in this tradition. Hald (p. 633) gives this assessment: "[It] is a pedagogical masterpiece; it became a standard text until it was superseded by expositions using matrix algebra." In 1876 Helmert published an article deriving the distribution of the sample variance for a normal population. The work was described in German textbooks, including his own, but the English statisticians 'Student' and Fisher did not know of it and re-derived the distribution.

From 1887 Helmert was professor of advanced geodesy at the University of Berlin and director of the Geodetic Institute.

Helmert received many honours. He was president of the global geodetic association of "Internationale Erdmessung", member of the Prussian Academy of Sciences in Berlin, was elected a member of the Royal Swedish Academy of Sciences in 1905, and recipient of some 25 German and foreign decorations.

July 30: Joel Stebbins

Joel Stebbins

July 30, 1878 – March 16, 1966

Joel Stebbins was an American astronomer who pioneered photoelectric photometry in astronomy.

He earned his Ph.D at the University of California. He was director of University of Illinois observatory from 1903 to 1922 and the Washburn Observatory at the University of Wisconsin-Madison from 1922 to 1948. After 1948, Stebbins continued his research at Lick Observatory until his final retirement in 1958.

Stebbins brought photoelectric photometry from its infancy in the early 1900s to a mature technique by the 1950s, when it succeeded photography as the primary method of photometry. Stebbins used the new technique to investigate eclipsing binaries, the reddening of starlight by interstellar dust, colors of galaxies, and variable stars.

Stebbins received the following awards:

• Rumford Prize of the American Academy of Arts and Sciences (1913)
• Henry Draper Medal of the National Academy of Sciences (1915)
• Bruce Medal of the Astronomical Society of the Pacific (1941)
• Gold Medal of the Royal Astronomical Society (1950)
• Henry Norris Russell Lectureship of the American Astronomical Society (1956)

The Lunar crater Stebbins and the asteroid 2300 Stebbins are named in his honor.

July 29: Mikhail Tikhonravov

Luna 3

Mikhail Tikhonravov

July 29, 1900 - March 3, 1974

Mikhail Klavdievich Tikhonravov, soviet pioneer of spacecraft design and rocketry. Mikhail Klavdievich attended the Zhukovsky Air Force Academy from 1922 to 1925, where he built gliders and was exposed to Konstantin Tsiolkovsky's ideas of spaceflight. In 1932, he joined GIRD, as one of the four brigade leaders. His brigade built the GIRD-09 rocket, fueled by liquid oxygen and jellied gasoline, and launched on August 17, 1933.

Tikhonravov remained in GIRD as it evolved into RNII, the jet propulsion institute, and then NII-1. In 1946, he became deputy chief of NII-4 in the Academy of Artillery Science. There, he lead a team of researchers that did important studies on packet rockets, satellite orbital motion, optimal pitch control programs for launching into orbit, reentry trajectories and heat shielding. This team designed Sputnik-3, Luna-1, Luna-3, Luna-4 and the early Venus and Mars probes. In 1956, Sergey Korolev had Tikhonravov and his team transferred into his bureau, OKB-1.

Tikhonravov Crater on Mars is named in his honor.

July 28: Charles Dillon Perrine

Charles Dillon Perrine

July 28, 1867–June 21, 1951

Charles Dillon Perrine was an Argentine astronomer.

Born in Ohio, he worked at Lick Observatory from 1893 to 1909 and then was director of the Argentine National Observatory (today, Observatorio Astronómico de Córdoba) in Argentina from 1909 until 1936.

In 1901, he and George Ritchey observed the apparent superluminal motion in the nebulosity surrounding Nova Persei 1901.

He discovered two moons of Jupiter, today known as Himalia (in 1904) and Elara (in 1905). They were simply designated "Jupiter VI" and "Jupiter VII" and were not given their present names until 1975.

He co-discovered the lost periodic comet 18D/Perrine-Mrkos and several other comets. Antonín Mrkos later named the asteroid 6779 Perrine after him.

He promoted the study of astrophysics in Argentina and pushed for the construction of a large telescope (the Bosque Alegre telescope), which however was not completed until 1942 (he had retired in 1936). He remained in Argentina after retirement and died there, in Villa General Mitre (which has since been renamed to its original name of Villa del Totoral). He is buried in the cementerio disidente in the city of Córdoba.

The lunar crater Perrine is named in his honor.

July 24: Henri Alexandre Deslandres

Henri Alexandre Deslandres

July 24, 1853 – January 15, 1948

Henri Alexandre Deslandres was a French astronomer, director of the Meudon and Paris Observatories.

Deslandres' undergraduate years at the École Polytechnique were played out against the aftermath of the Franco-Prussian War and the chaos of the Paris Commune so, on graduation in 1874, he responded to the continuing military tension with the emerging Germany by embarking on a military career. Rising to the rank of captain in the engineers, he became increasingly interested in physics and, in 1881, resigned his commission to join Alfred Cornu's laboratory at the École Polytechnique, working on spectroscopy. He continued his spectroscopic work at the Sorbonne, earning his doctorate in 1888 and finding numerical patterns in spectral lines that paralleled the work of Johann Balmer and were to catalyse the development of quantum mechanics in the 20th century.

In 1868, Pierre Janssen's solar observations had led him to report to the Académie des Sciences that

It is no longer geometry and mechanics which dominate [in astronomy] but physics and chemistry.

Such advice was sternly rejected by director of the Paris Observatory Urbain Le Verrier and the French government awarded Janssen a grant to establish an astrophysical observatory at Meudon on the outskirts of Paris with Janssen as the sole astronomer. In 1889, Le Verrier was succeeded by Amédée Mouchez who set to work to bring astrophysics into the mainstream by hiring Deslandres. Deslandres developed the spectroheliograph simultaneously with George Hale.

In 1898, he joined Janssen at Meudon, increasing the scientific staff by 100%. On Janssen's death in 1907, Deslandres became director and embarked on a programme of expansion. At the outbreak of World War I in 1914, though already in his 60s, he returned to active service in the engineers as a major and later lieutenant colonel. In 1918, following the armistice, he resumed his office at Meudon until 1926 when its administration merged with that of the Paris Observatory, Mouchez assuming the role of director of both institutions until his retirement in 1929.

He remained active in research right up until his death. Fellow astronomer Raymond Michard observed that In his bearing, his character and his style of life Deslandres always remained more akin to the soldier (and the officer) than to the scholar.

Deslandres was awarded the Gold Medal of the Royal Astronomical Society (1913), the Henry Draper Medal of the National Academy of Sciences (1913) and the Bruce Medal of the Astronomical Society of the Pacific (1921).

The crater Deslandres on the Moon and asteroid 11763 Deslandres are named in his honor.

July 23: Vera Rubin

Vera (Cooper) Rubin

July 23, 1928

Vera Rubin is an American astronomer who pioneered work on galaxy rotation rates. Her opus magnus was the uncovering of the discrepancy between the predicted angular motion of galaxies and the observed motion, by studying galactic rotation curves. This phenomena became known as the galaxy rotation problem.

Currently, the theory of dark matter is the most popular candidate for explaining this. The alternative theory of MOND (Modified Newtonian Dynamics) has little support in the community.

After she earned an A.B. from Vassar College (1948) she tried to enroll at Princeton but never received their graduate catalog as women there were not allowed in the graduate astronomy program until 1975. She applied to Cornell University, where she studied physics under Philip Morrison, Richard Feynman, and Hans Bethe. There she earned a M.A. in 1951. Then in 1954 at Georgetown University she earned a Ph.D.

Vera Rubin also has honorary Doctors of Science degrees from numerous universities, including Harvard and Yale. Rubin is currently a research astronomer at the Carnegie Institution of Washington. She is a member of the US National Academy of Sciences and the Pontifical Academy of Sciences. So far she has co-authored 114 peer reviewed research papers.

She is the author of Bright Galaxies Dark Matters.

Rubin received the Gold Medal of the Royal Astronomical Society in 1996. She was only the second female recipient of this medal, the first being Caroline Herschel in 1828.

The asteroid 5726 Rubin is named in her honor.

July 22: Friedrich Bessel

Friedrich Wilhelm Bessel

July 22, 1784 – March 17, 1846

Friedrich Bessel was a German mathematician, astronomer, and systematizer of the Bessel functions (which were discovered by Daniel Bernoulli). He was a contemporary of Carl Gauss, also a mathematician and astronomer.

Bessel was born in Minden in Minden-Ravensberg, the son of a civil servant. At the age of 14 Bessel was apprenticed to the import-export concern Kulenkamp. He soon became the company's accountant. The business's reliance on cargo ships led him to turn his mathematical skills to problems in navigation. This in turn led to an interest in astronomy as a way of determining longitude.

Bessel came to the attention of a major figure of German astronomy at the time, Heinrich Wilhelm Olbers, by producing a refinement on the orbital calculations for Halley's Comet. Within two years Bessel had left Kulenkamp and become an assistant at Lilienthal Observatory near Bremen. There he worked on James Bradley's stellar observations to produce precise positions for some 3,222 stars.

This work attracted considerable attention, and at the age of 26 Bessel was appointed director of the Königsberg Observatory by King Frederick William III of Prussia. There he published tables of atmospheric refraction based on Bradley's observations, which won him the Lalande Prize from the Institut de France. Bessel was able to pin down the position of over 50,000 stars during his time at Königsberg.

With this work under his belt, Bessel was able to achieve the feat for which he is best remembered today: he is credited with being the first to use parallax in calculating the distance to a star. Astronomers had believed for some time that parallax would provide the first accurate measurement of interstellar distances—in fact, in the 1830s there was a fierce competition between astronomers to be the first to measure a stellar parallax accurately. In 1838 Bessel won the race, announcing that 61 Cygni had a parallax of 0.314 arcseconds; which, given the diameter of the Earth's orbit, indicated that the star was about 3 parsecs (9.8 light years) away. He narrowly beat Friedrich Georg Wilhelm Struve and Thomas Henderson, who measured the parallaxes of Vega and Alpha Centauri in the same year.

As well as helping determine the parallax of 61 Cygni, Bessel's precise measurements allowed him to notice deviations in the motions of Sirius and Procyon, which he deduced must be caused by the gravitational attraction of unseen companions. His announcement of Sirius's "dark companion" in 1844 was the first correct claim of a previously unobserved companion by positional measurement, and eventually led to the discovery of Sirius B.

Despite lacking a university education, Bessel was a major figure in astronomy during his lifetime. He was elected a fellow of the Royal Society, won the Gold Medal of the Royal Astronomical Society in 1841 and the largest crater in the Moon's Mare Serenitatis is named Bessel after him. The asteroid 1552 Bessel was also named in his honor.

July 21: Jean-Felix Picard

Jean-Felix Picard

July 21, 1620 – July 12, 1682

Jean Picard was a French astronomer and priest born in La Flèche, where he studied at the Jesuit Collège Royal Henry-Le-Grand. He was the first person to measure the size of the Earth to a reasonable degree of accuracy in a survey conducted 1669-70, for which he is honored with a pyramid at Juvisy-sur-Orge.

Guided by Maurolycus's methodology and Snellius's mathematics for doing so, Picard achieved this by measuring one degree of latitude along the Paris Meridian using triangulation along thirteen triangles stretching from Paris to the clocktower of Sourdon, near Amiens. His measurements produced a result of 110.46 km for one degree of latitude, which gives a corresponding terrestrial radius of 6328.9 km. The polar radius has now been measured at just over 6357 km. This was an error only 0.44% less than the modern value. This was another example of advances in astronomy and its tools making possible advances in cartography.

Picard was the first to attach a telescope with crosswires (developed by William Gascoigne) to a quadrant, and one of the first to use a micrometer screw on his instruments. The quadrant he used to determine the size of the Earth had a radius of 38 inches and was graduated to quarter-minutes. The sextant he used to find the meridian had a radius of six feet, and was equipped with a micrometer to enable minute adjustments. These equipment improvements made the margin of error only ten seconds, as opposed to Tycho Brahe's four minutes of error. This made his measurements 36 times more accurate. Isaac Newton was to use this value in his theory of universal gravitation.

Picard also travelled to Tycho Brahe's Swedish observatory, Uraniborg, in order to assess its position accurately to compare Tycho's readings to others'.

Picard collaborated and corresponded with many scientists, including Newton, Christian Huygens, Römer, Bartholin, Hudde, and even his main competitor, Giovanni Cassini, although Cassini was often less than willing to return the gesture. These correspondences led to Picard's contributions to areas of science outside the field of geodesy, such as the aberration of light he observed while in Uraniborg, or his discovery of mercurial phosphorescence upon his observance of the faint glowing of a barometer. This discovery led to Newton's studies of spectrometry.

Picard also developed the system of right ascension for measuring positions of celestial objects in relation to the Earth.

His book "Mesure de la Terre" was published in 1671.

The Lunar crater Picard, on the northwest quadrant of Mare Crisium and the PICARD mission, an orbiting solar observatory, are named in his honor.

July 20: Ormsby M. Mitchel

Ormbsy MacKnight Mitchel

July 20, 1805 – October 30, 1862

Ormbsy MacKnight (or McKnight) Mitchel was an American astronomer and major general in the American Civil War.

A multi-talented man, he was also an attorney, surveyor, and publisher. He is notable for publishing the first magazine in the United States devoted to astronomy. Known in the Union Army as "Old Stars", he is best known for ordering the raid that became famous as the Great Locomotive Chase during the Civil War.

The U.S. communities of Mitchell, Indiana, Mitchelville, South Carolina, and Fort Mitchell, Kentucky were named for him.

Mitchel received an appointment to the United States Military Academy in 1825, where he was a classmate to Robert E. Lee and Joseph E. Johnston. He stayed at West Point as assistant professor of mathematics for three years. He helped establish observatories for the United States Navy and at Harvard University.

In 1845, he was appointed director of an observatory established at Cincinnati College through his initiative. At the time, it featured the second-largest refracting telescope in the world. He published the first monthly magazine in the United States devoted specifically to astronomy. In 1859, Mitchel became superintendent of the Dudley Observatory at Albany, New York, where he continued his pioneering work on the development of telegraphic determination of longitude.

A persistently bright region near the Mars south pole that was first observed by Mitchel in 1846 is named in his honor - 'The Mountains of Mitchel'. It is located near 70°S, 40°E. An impact crater on Mars was named in his honor.

July 19: Edward Charles Pickering

Edward Charles Pickering

July 19, 1846–February 3, 1919

Edward Charles Pickering was an American astronomer and physicist, brother of William Henry Pickering.

Along with Carl Vogel, Pickering discovered the first spectroscopic binary stars. He wrote Elements of Physical Manipulations (2 vol., 1873–76).

Pickering attended Boston Latin School, and received his B.S. from Harvard in 1865. Later, he served as director of Harvard College Observatory from 1877 to his death in 1919, where he made great leaps forward in the gathering of stellar spectra through the use of photography. At Harvard, he recruited many women to work for him, including Annie Jump Cannon, Henrietta Swan Leavitt, and Antonia Maury. These women, who came to be known as "Pickering's Harem" by the scientific community, made several important discoveries at HCO.

In 1876 he co-founded the Appalachian Mountain Club.

In 1911 he co-founded the American Association of Variable Star Observers (AAVSO) with William T. Olcott.

Pickering received the Gold Medal of the Royal Astronomical Society (1886 and 1901), the Henry Draper Medal (1888) and the Bruce Medal (1908)

The Lunar crater Pickering, the crater Pickering Mars and the asteroid 784 Pickeringia are named in his honor.

July 18: Robert Hooke

Robert Hooke

July 18, 1635 – March 3, 1703

Robert Hooke, FRS was an English natural philosopher and polymath who played an important role in the scientific revolution, through both experimental and theoretical work.

Hooke is known principally for his law of elasticity (Hooke's Law). He is also remembered for his work as "the father of microscopy" — it was Hooke who coined the term "cell" to describe the basic unit of life. He also assisted Robert Boyle and built the vacuum pumps used in Boyle's gas law experiments. Hooke was an important architect of his time, and a chief surveyor to the City of London after the Great Fire. He built some of the earliest Gregorian telescopes, observed the rotations of Mars and Jupiter, and, based on his observations of fossils, was an early proponent of biological evolution. He investigated the phenomenon of refraction, deducing the wave theory of light, and was the first to suggest that matter expands when heated and that air is made of small particles separated by relatively large distances. He also deduced from experiments that gravity follows an inverse square law, and that such a relation governs the motions of the planets, an idea which was subsequently developed by Newton. Much of Hooke's work was conducted in his capacity as curator of experiments of the Royal Society, a post he held from 1662.

Hooke was, by all accounts, a remarkably industrious man, and was at one time simultaneously the curator of the Royal Society and a member of its council, Gresham Professor of Geometry and Chief Surveyor to the City of London.

Hooke's reputation suffered during the eighteenth century, and this is popularly attributed to a dispute with Isaac Newton over credit for his work on gravitation; Newton, as President of the Royal Society, did much to obscure Hooke, including, it is said, destroying (or failing to preserve) the only known portrait of the man. Hooke's reputation was revived during the twentieth century through studies of Robert Gunther and Margaret 'Espinasse, and after a long period of relative obscurity he is now recognized as one of the most important scientists of his age.

One of the more-challenging problems tackled by Hooke was the measurement of the distance to a star (other than the Sun). The star chosen was Gamma Draconis and the method to be used was parallax determination. After several months of observing, in 1669, Hooke believed that the desired result had been achieved. It is now known that Hooke's equipment was far too imprecise to allow the measurement to succeed. Gamma Draconis was the same star William Bradley used in 1725 in discovering the aberration of light.

Hooke's activities in astronomy extended beyond the study of stellar distance. His Micrographia contains illustrations of the Pleiades star cluster as well as of lunar craters. He performed experiments to study how such craters might have formed. Hooke also was an early observer of the rings of Saturn, and discovered one of the first double-star systems, Gamma Arietis, in 1664.

On 8 July 1680, Hooke observed the nodal patterns associated with the modes of vibration of glass plates. He ran a bow along the edge of a glass plate covered with flour, and saw the nodal patterns emerge.

The Lunar crater Hooke, a crater on Mars and the asteroid 3514 Hooke (1971 UJ) are named in his honor.

July 17: Barnaba Oriani

Barnaba Oriani

July 17 1752 - November 12 1832

Barnaba Oriani was an Italian geodesist, astronomer and scientist.

After getting his elementary education in Carignano, he went on to study at the College of San Alessandro in Milan, under the tutelage and with the support of the Order of Barnabus, which he later joined. After completing his studies in the humanities, physical and mathematical sciences, philosophy, and theology, he was ordained as a priest in 1775.

When Napoleon established the Republic of Lombardy, Oriani refused to swear an oath against the monarchy, and the new republican government modified the oath of allegiance on his behalf. He was retained in his position at the observatory and was made president of the commission appointed to regulate the new system of weights and measures.

When the republic became a Napoleonic kingdom, Oriani was awarded the Iron Crown and the Legion of Honour, was made a count and senator, and was appointed to measure the arc of the meridian between the zeniths of Rimini and Rome.

Oriani was a devoted friend of the Theatine monk, Giuseppe Piazzi, the discoverer of Ceres. Oriani and Piazzi worked together for thirty-seven years, cooperating on many astronomical observations.

Given his strong interest in astronomy, Oriani was appointed on the staff of the Observatory of Brera in Milan in 1776, becoming assistant astronomer in 1778 and director in 1802. In 1778 he began publishing various in-depth dissertations on astronomical objects, the Effemeridi di Milano (Ephemerides of Milan).

A very capable astronomer, Oriani's work began to attract considerable attention. His research in the areas of astronomic refraction, the obliquity of the ecliptic and orbital theory were of considerable noteworthiness in themselves; but his greatest achievement was his detailed research of the planet Uranus, which had been discovered by Sir William Herschel in 1781. Oriani devoted significant time to observations of Uranus, calculating its orbital properties, which he published as a booklet of tables in 1793.

After others had shown that Uranus was not on a parabolic orbit but rather in a roughly circular orbit, he calculated the orbit in 1783. In 1789, Oriani improved his calculations by accounting for the gravitational effects of Jupiter and Saturn.

In addition to his continual contributions to the Effemeridi, he published a series of memoirs on spherical trigonometry: the Memorie dell' Istituto Italiano, 1806-10, and the Istruzione suelle misure e sui pesi, 1831.

For his work in astronomy, Oriani was honored by naming asteroid (4540) "Oriani". This asteroid had been discovered at the Osservatorio San Vittore in Bologna, Italy on November 6, 1988.

July 16: Edwin Brant Frost

Edwin B. Frost, Christian T. Elvey, and Otto Struve, Yerkes Observatory, circa 1933.

Edwin Brant Frost II

July 16, 1866 – May 14, 1935

Edwin Frost was an American astronomer, born in Brattleboro, Vermont. His father, Carlton Pennington Frost, was dean of Dartmouth Medical School.

Frost graduated from Dartmouth in 1886. He continued his education as a post-graduate student in chemistry and in 1887 became an instructor in physics while only 21 years old. In 1890 Frost went abroad to Europe and ended up researching stellar spectroscopy under Hermann Vogel in Potsdam. He returned to Dartmouth in 1892 as an assistant professor of astronomy.

He was fond of the outdoors and enjoyed golf, swimming, and ice skating. He also enjoyed music and literature. In 1896 he married Mary E. Hazard. They had three children, Katharine, Fredrick, and Benjamin.

Frost joined the staff of Yerkes Observatory in 1898 and became its director in 1905 when George Hale resigned. Frost kept the position until his retirement in 1932. He was the editor of the Astrophysical Journal from 1902 to 1932, known for his careful attention to details. In 1915 he lost the use of his right eye and in 1921, his left. Despite his blindness he continued working for eleven more years until his retirement in 1932.

Frost's research focused on the determination of radial velocity using stellar spectroscopy and spectroscopic binaries. In 1902, he discovered the strange behavior of Beta Cephei, which later became the prototype for Beta Cephei variable stars.

He played a significant role in bringing Otto Struve to the United States, when the latter was living as an impoverished refugee in Turkey after the Russian Revolution. He later supported the appointment of Struve as his successor as director of Yerkes Observatory.

The Lunar crater Frost is named in his honor.

July 15: Jocelyn Bell Burnell

Dame Susan Jocelyn Bell Burnell, DBE, FRS, FRAS

July 15, 1943

Jocelyn Bell Burnell, DBE, FRS, FRAS, known as Jocelyn Bell Burnell, is a British astrophysicist who, as a postgraduate student, discovered the first radio pulsars with her thesis supervisor Antony Hewish, for which Hewish was awarded a Nobel Prize.

The paper announcing the discovery had five authors, Hewish's name being listed first, Bell's second. Hewish was awarded the Nobel Prize, along with Martin Ryle, without the inclusion of Bell as a co-recipient, which was controversial, and was roundly condemned by Hewish's fellow astronomer Fred Hoyle. The Royal Swedish Academy of Sciences, in their press release announcing the 1974 Nobel Prize in Physics, cited Ryle and Hewish for their pioneering work in radio-astrophysics, with particular mention of Ryle's work on aperture-synthesis technique, and Hewish's decisive role in the discovery of pulsars. Iosif Shklovsky, recipient of the 1972 Bruce Medal, had sought out Bell at the 1970 IAU General Assembly, to tell her:

"Miss Bell, you have made the greatest astronomical discovery of the twentieth century."

Born in Belfast, Northern Ireland, where her father was an architect for the nearby Armagh Planetarium, she enjoyed a large library and was encouraged to read. She was especially drawn to the books on astronomy. She attended Lurgan College and lived in Lurgan as a child. She was one of the first girls at the college permitted to study science. Previously, the girls' curriculum had included cross-stitch and cookery. At eleven, she failed the 11+ exam and her parents sent her to the Mount School, York, a Quaker girls' boarding school. There she was impressed by a physics teacher who taught her:

"You don't have to learn lots and lots...of facts; you just learn a few key things, and...then you can apply and build and develop from those... He was a really good teacher and showed me, actually, how easy physics was."

She graduated from the University of Glasgow with a B.Sc. physics in 1965 and received her Ph.D. from New Hall (renamed Murray Edwards College) of the University of Cambridge in 1969. At Cambridge, she worked with Hewish and others to construct a radio telescope for using interplanetary scintillation to study quasars, which had recently been discovered (interplanetary scintillation allows compact sources to be distinguished from extended ones). In July 1967, detecting a bit of "scruff" on her chart recorder papers that tracked across the sky with the stars, Bell Burnell found that the signal was regularly pulsing, about once each second. Temporarily dubbed "Little Green Man 1" the source (now known as PSR B1919+21) was eventually identified as a rapidly rotating neutron star.

After finishing her PhD, Bell Burnell worked at the University of Southampton (1968-73), University College London (1974-82) and the Royal Observatory, Edinburgh (1982-91). In addition, from 1973 to 1987 she was also a tutor, consultant, examiner and lecturer for the Open University. In 1991 she was appointed Professor of Physics at the Open University, a position she held for ten years. She was also a visiting professor at Princeton University. Before retiring Bell Burnell was Dean of Science at the University of Bath between 2001 and 2004, and was President of the Royal Astronomical Society between 2002 and 2004. She is currently Visiting Professor of Astrophysics at the University of Oxford and a Fellow of Mansfield College. She is the current President of the Institute of Physics.

Although she didn't share the 1974 Nobel Prize for Physics with Hewish for her discovery, she has been honoured by many other organisations:

• Michelson Medal of the Franklin Institute (1973, jointly with Hewish).
• J. Robert Oppenheimer Memorial Prize from the Center for Theoretical Studies in Miami (1978).
• Beatrice M. Tinsley Prize of the American Astronomical Society (1987).
• Herschel Medal of the Royal Astronomical Society (1989).
• Karl G. Jansky Lectureship of the National Radio Astronomy Observatory(1995).
• Magellanic Premium of the American Philosophical Society (2000).
• Fellow of the Royal Society (March 2003).

She has been awarded numerous honorary degrees, for instance, recently:

• In 2007 she was awarded an honorary doctorate by Harvard University.
• On 23 June 2007, Bell Burnell was awarded an Honorary Doctorate of Science from the University of Durham.
• She also holds important awards in the British honours system. In 1999 Bell Burnell received a CBE from Queen Elizabeth II. In June 2007 she was awarded a DBE (equivalent to a male knighthood).

July 14: Jacques d'Allonville

Antoine Caron: Astronomers Studying an Eclipse

Jacques Eugène d'Allonville, Chevalier de Louville par Fontenelle

July 14, 1671 – September, 1732

Jacques Eugène d'Allonville, Chevalier de Louville par Fontenelle was a French astronomer and mathematician.

He was born in the Château de Louville, and studied mathematics before joining the navy. He achieved the rank of colonel before retiring from military service in 1713, following the peace of Utrecht. He thereafter took up the study of astronomy.

He is noted for determining a method for precisely calculating the occurrence of solar eclipses.

The crater Louville on the Moon is named in his honor.

July 13: Heinrich Louis d'Arrest

Heinrich Louis d'Arrest

July 13, 1822 – June 14, 1875

Heinrich Louis d'Arrest was a Prussian astronomer, born in Berlin.

While still a student at the University of Berlin, d'Arrest was party to Johann Gottfried Galle's search for Neptune. On September 23, 1846, he suggested that a recently drawn chart of the sky, in the region of Urbain Le Verrier's predicted location, could be compared with the current sky to seek the displacement characteristic of a planet, as opposed to a stationary star. Neptune was discovered that very night.

D'Arrest's later work at the Leipzig Observatory led him, in 1851, to the discovery of the comet named for him (formally designated 6P/d'Arrest). He also studied asteroids (he discovered 76 Freia) and nebulae.

He won the Gold Medal of the Royal Astronomical Society in 1875.

The crater D'Arrest on the Moon is named after him, as well as a crater on the Martian satellite Phobos and the asteroid 9133 d'Arrest.

July 12: Robert Main

The Royal Astronomical Society

Reverend Robert Main

July 12, 1808 – May 9, 1878

The Reverend Robert Main was an English astronomer.

Born in Kent, the eldest son of Thomas Main, Robert Main attended school in Portsea before studying mathematics at Queens' College, Cambridge, where he graduated in 1834. He served for twenty-five years (1835-60) as First Assistant at the Royal Greenwich Observatory, and published numerous articles, particularly on stellar and planetary motion, stellar parallax, and the dimensions and shapes of the planets. From 1841 to 1861 he was successively an honorary secretary, a vice-president, and President of the Royal Astronomical Society, and in 1858 was awarded the Society's Gold Medal. In 1860 he became director of Radcliffe Observatory at Oxford University after the death of Manuel Johnson, and was elected as a Fellow of the Royal Society.

He supervised the third (1859) edition of Sir John Herschel's A Manual of Scientific Enquiry, prepared for the use of Her Majesty's Navy and adapted for travellers in general (1849), which included an article on geology by Charles Darwin. His textbook Practical and Spherical Astronomy was published in 1863. He was responsible for editing the Second Radcliffe Catalogue (1870), which detailed 6,317 stars, and (with Charles Pritchard) Herschel's Catalogue of 10,300 multiple and double stars (1874). He also published observations made of rainfall in Oxford over 25 years from 1851 to 1875, and contributed to the Fortnightly Review during the editorship of G. H. Lewes.

He was an ordained priest of the Church of England who preached regularly while living in Greenwich, and his works include the annual address for 1875 to the Philosophical Society at the Victoria Institute (entitled Modern Philosophic Scepticism Examined) and a sermon on I Corinthians 1:22-24 given to the British Association for the Advancement of Science in the same year. He completed the questionnaire on which Francis Galton based his English Men of Science (1874), and his recorded answers included the following comments:

“I take considerable pains in the investigation of religious matters, one of my amusements being the collection of a considerable theological library, with the books of which I am familiar.”

“I am not aware of any innate taste for science... My interest in astronomy, especially, was very small indeed until I was appointed.”

The lunar crater Main and a crater on Mars are 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.

July 10: Alvan Graham Clark

Alvan Graham Clark

July 10, 1832 – June 9, 1897

Alvan Graham Clark was an American astronomer and telescope-maker. He was the son of Alvan Clark, founder of Alvan Clark & Sons.

Alvan Clark & Sons was an American maker of optics that became famous for crafting lenses for some of the largest refracting telescopes of the nineteenth and early twentieth centuries. Founded in 1846 in Cambridgeport, Massachusetts by Alvan Clark (1804–1887), a descendant of Cape Cod whalers who started as a portrait painter, and his sons George Bassett Clark (1827–1891) and Alvan Graham Clark. Five times, the firm built the largest refracting telescopes in the world.

On January 31, 1862, while testing a new 18 1/2 inch refracting telescope, he made the first observation of Sirius B in Cambridgeport, Massachusetts. The magnitude 8 companion of Sirius is also the first known white dwarf star.

The 18 1/2 inch refracting telescope is now still being used at the landmark Dearborn Observatory of Northwestern University in Evanston, IL.

For many years the Dearborn Telescope, the largest telescope in the world in its time, has been one of the most popular exhibits at the Adler Planetarium. The telescope has had an unusually varied career, and was recently sent out for a careful, professional facelift before resuming its place in the New Adler.

July 9: Leo Brenner

Spiridon Gopcevic

July 9, 1855 – 1928

Spiridon Gopcevic or Gopcevia was a Serbian astronomer and historian. He is also known by his pen name of Leo Brenner.

He was born to a shipowner in the Austrian litoral town of Triest (today in Italy), and at an early age, after his father died, was sent to Vienna to be educated. Following the death of his mother, he became a journalist by trade.

Among his works he published Macedonia and Old Serbia in 1889, an ethnographic study. However he spent time in jail in 1893 due to some of his articles against the Austro-Hungarian government, and decided to end his journalistic career.

In 1893 he founded Manora Observatory on Mali Lošinj. This observatory was named for his wife, a wealthy Austrian noblewoman. At this observatory, Spiridon used the 17.5cm refractor telescope at the observatory to make observations of Mars, the rings of Saturn, and other planets. However he would eventually close the observatory in 1909 due to financial problems.

From 1899 until 1908 he was the founder and editor of the Astronomische Rundschau, a popular scientific journal. He spent several years in America before returning to Europe and editing an army journal in Berlin during the war. The circumstances of his death are somewhat uncertain, but he appears to have been impoverished.

The crater Brenner on the Moon was named after him (based on his nom de plume) by his friend Phillip Fauth. A new observatory was built on Mali Lošinj in 1993, and was named "Leo Brenner".

July 8: Christiaan Huygens

Christiaan Huygens

April 14, 1629 – July 8, 1695

Christiaan Huygens was a prominent Dutch mathematician, astronomer, physicist, and horologist. His work included early telescopic studies, investigations and inventions related to time keeping, and studies of both optics and centrifugal force.

Christiaan Huygens studied law and mathematics at the University of Leiden and the College of Orange in Breda before turning to science.

Huygens achieved note for his argument that light consists of waves, which became instrumental in the understanding of wave-particle duality. He generally receives credit for his role in the development of modern calculus and his original observations on sound perception.

In 1655, Huygens proposed that Saturn was surrounded by a solid ring, "a thin, flat ring, nowhere touching, and inclined to the ecliptic." Using a 50 power refracting telescope that he designed himself, Huygens also discovered the first of Saturn's moons, Titan. In the same year he observed and sketched the Orion Nebula. His drawing, the first such known of the Orion nebula, was published in Systema Saturnium in 1659. Using his modern telescope he succeeded in subdividing the nebula into different stars. (The brighter interior of the Orion Nebula bears the name of the Huygens Region in his honour.) He also discovered several interstellar nebulae and some double stars.

Huygens formulated also what is now known as the second law of motion of Isaac Newton in a quadratic form. Newton reformulated and generalized that law.

After Blaise Pascal encouraged him to do so, Huygens wrote the first book on probability theory, which he had published in 1657.

On May 3, 1661, he observed planet Mercury transit over the Sun, using the telescope of telescope maker Richard Reeves in London together with astronomer Thomas Streete and Richard Reeves.

The Royal Society elected Huygens a member in 1663. In the year 1666 Huygens moved to Paris where he held a position at the French Academy of Sciences under the patronage of Louis XIV. Using the Paris Observatory (completed in 1672) he made further astronomical observations. In 1684 he published "Astroscopia Compendiaria" which presented his new aerial (tubeless) telescope.

Huygens speculated in detail about life on other planets. In his book Cosmotheoros, further entitled The celestial worlds discover'd: or, conjectures concerning the inhabitants, plants and productions of the worlds in the planets, he imagined a universe brimming with life, much of it very similar to life on 17th-century Earth. The liberal climate in the Netherlands of that time not only allowed but encouraged such speculation. In sharp contrast, philosopher Giordano Bruno, who also believed in many inhabited worlds, was burned at the stake by the Italian authorities for his beliefs in 1600.

The Huygens probe: The lander for the Saturnian moon Titan, part of the Cassini-Huygens Mission to Saturn, Asteroid 2801 Huygens, a crater on Mars and Mons Huygens, a mountain on the Moon are named in his honor.