January 16: Johannes Schöner

Johannes Schöner

January 16, 1477 – January 16, 1547

Johannes Schöner was a renowned and respected German polymath. It is best to refer to him using the usual 16th century Latin term "mathematicus", as the areas of study to which he devoted his life were very different from those now considered to be the domain of the mathematician. He was a priest, astronomer, astrologer, geographer, cosmographer, cartographer, mathematician, globe and scientific instrument maker and editor and publisher of scientific tests.

In his own time he enjoyed a European-wide reputation as an innovative and influential globe maker and cosmographer and as one of the continents leading and most authoritative astrologers. Today he is remembered as an influential pioneer in the history of globe making and as a man who played a significant role in the events that led up to the publishing of Copernicus' "De revolutionibus" in Nürnberg in 1543.

Schöner had made still unpublished data of Mercury observations from Walther available to Copernicus, 45 observations in total, 14 of them with longitude and latitude. Copernicus used three of them in "De revolutionibus", giving only longitudes, and falsely attributing them to Schöner. The values differed slightly from the ones published by Schöner in 1544.

In 1538, Georg Joachim Rheticus, a young professor of mathematics at Wittenberg, stayed for some time with Schöner who convinced him to visit Nicolaus Copernicus in Frauenburg. In 1540, Rheticus dedicated the first published report of Copernicus work, the Narratio prima, to Schöner. As this was well received, Copernicus finally agreed to publish his main work, and Rheticus prepared Copernicus' manuscript for printing.

A crater on Mars is named in his honor.

October 30: Marcin Poczobutt

Marcin Odlanicki Poczobutt

October 30, 1728 – February 7, 1810

Marcin Poczobutt was a Polish-Lithuanian astronomer, jesuit and mathematician.

He became mathematics professor and rector of the Vilnius University where he organized the construction of the university's observatory and the purchase of the equipment. He also made observations of solar and lunar eclipses, comets and asteroids. In addition, he made measurements of Mercury to compute an orbit, and also determined the geographic coordinates of locations in Lithuania, including Vilnius.

He was granted the title of the King's Astronomer and became a member of the British Royal Academy of Science.

The Lunar crater Poczobutt is named in his honor.

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.

February 10: Eugène Michel Antoniadi

Eugène Michel Antoniadi

March 1, 1870 – February 10, 1944

Eugène Michel Antoniadi was a Greek astronomer who spent most of his life in France. His first publications date from the late 1880s, and his last ones from 1941 or 1942. He is best known for his work concerning the planets Mars and Mercury, and drew the best pre-Space Age maps of them, despite the fact that his first attempts to draw a map of Mercury were flawed by his incorrect assumption that Mercury had synchronous rotation with the Sun.

He became a highly reputed observer of Mars, and at first supported the notion of Martian canals. In 1909, using the great 83-cm aperture refracting telescope of the Meudon Observatory near Paris under ideal observing conditions, he demonstrated that the so-called “canals” of Mars were optical illusions.

He is also famed for creating the Antoniadi scale of seeing, which is commonly used by amateur astronomers. Now the scale is seen as the metric system of astronomy, being used as a default measurement all over the world.

The scale is on a 5 point system, with one being the best seeing conditions and 5 being worst. The actual definitions are as follows:

I.   Perfect seeing, without a quiver.

II.  Slight quivering of the image with moments of calm lasting several seconds.

III. Moderate seeing with larger air tremors that blur the image.

IV. Poor seeing, constant troublesome undulations of the image.

V.  Very bad seeing, hardly stable enough to allow a rough sketch to be made.

Note: the scale is usually indicated by use of a Roman numeral.

Antoniadi was also a noted historian, as well as a superb artist, writing about the pyramids and Egyptian astronomy. In the early twentieth century he further demonstrated his skills as an architect by compiling a great three-volume work on the mosque of St Sophia in Constantinople (now Istanbul). He was also a strong chess player. His best result was equal first with Frank Marshall in a tournament in Paris in 1907, a point ahead of Savielly Tartakower.

A crater on Mars and the crater Antoniadi on the Moon were named in his honor, as well as Antoniadi Dorsum on Mercury itself. 

January 22: Pierre Gassendi

Pierre Gassendi

January 22, 1592 – October 24, 1655

Pierre Gassendi was a French philosopher, priest, scientist, astronomer, and mathematician. With a church position in south-east France, he also spent much time in Paris, where he was a leader of a group of free-thinking intellectuals. 

He was also an active observational scientist. In 1631, Gassendi became the first person to observe the transit of a planet across the Sun, viewing the transit of Mercury that Kepler had predicted. He was then the first to publish data on the transit. In December of the same year, he watched for the transit of Venus, but this event occurred when it was night time in Paris. 

He wrote numerous philosophical works, and some of the positions he worked out are considered significant, finding a way between scepticism and dogmatism. Richard Popkin indicates that Gassendi was one of the first thinkers to formulate the modern "scientific outlook", of moderated scepticism and empiricism. He clashed with his contemporary Descartes on the possibility of certain knowledge. His best known intellectual project attempted to reconcile Epicurean atomism with Christianity. (In natural philosophy, atomism is the theory that all the objects in the universe are composed of very small, indestructible building blocks – atoms.)

In 1653 he published works on the lives of Copernicus and of Tycho Brahe. The Lunar crater Gassendi is named after him.