Tycho Brahe (1546-1601) - Danish astronomer

Born on December 14, 1546, Tycho [Tyge] Brahe was probably the greatest pre-telescopic astronomer. He was born in his parents’ large manor house at Knutstorp, in the Danish region of Scarnia, which is now in Sweden. Tycho Brahe was given the name Tyge by his parents Beate Bille and Otte Brahe. He is now known as "Tycho" since that is the Latinized version of his name that he adopted when he was about fifteen years old.

Otte Brahe, his father, was from the Danish nobility Beate Bille, Tycho's mother, also came from an important family which had produced leading churchmen and politicians. Tycho Brahe was brought up by his paternal uncle Jorgen Brahe and became his heir.

He was sent by his family to study in Copenhagen, then to Leipzig to study law, but also studied a variety of other subjects and became interested in astronomy. In 1565 and 1566 Tycho studied mathematics at the universities in Wittenburg and Rostock.

He began making observations and by August 1563, while still at the University of Leipzig, he began to keep a record of these observations. The second observation he recorded was a conjunction of Jupiter and Saturn which proved significant for Tycho's subsequent career.

In spring 1569, he arrived in Augsburg, where he spent 14 months learning how to make high-precision astronomical instruments. His ambition was to build instruments allowing him to make observations true to within one arc minute (one-sixtieth of a degree).

Tycho's reputation as an accomplished astronomer rose quickly, primarily through his

observations of and writings on the 1572 novae in Cassiopea, and of the 1577 comet.

On November 11, 1572 Tycho observed the new star in Cassiopeia. Observing the night sky from an uncle’s home, Tycho was amazed to see a new light brighter than Venus in the sky. In 1573, Tycho’s name became well-known in astronomical circles when he published De nova stella – The New Star.

In 1598 was appointed Imperial Mathematician to the Holy Roman Emperor Rudolf II. Tycho Brahe's contributions to astronomy were enormous. He not only designed and built instruments, he also calibrated them and checked their accuracy periodically. He thus revolutionized astronomical instrumentation.

His astronomical research program never really resumed, however. He died in Prague, Bohemia (now Czech Republic) on October 24, 1601, leaving his most recent assistant Johannes Kepler as his scientific heir.
Tycho Brahe (1546-1601) - Danish astronomer

Sir Joseph Norman Lockyer (17 May 1836 – 16 August 1920) – British astronomer

Sir Joseph Norman Lockyer born in Rugby, England, was one of the pioneers of astronomical spectroscopy and became one of the most influential astronomers of his time. His father, Joseph Hooley Lockyer, was a surgeon-apothecary with broad scientific interests, and his mother, Anne Norman, was a daughter of Edward Norman, the squire of Cosford, Warwickshire.

His earliest employment was as a civil servant in the English War Office, which he entered in 1857. He pursued his interest in astronomy on an amateur basis. He was elected a Fellow of the Royal Society on March 14, 1862, and his rising reputation as a solar physicist led him to be appointed in 1885 Director of the Solar Physics Observatory in South Kensington.

In the 1860s he became fascinated by electromagnetic spectroscopy as an analytical tool for determining the gas composition of heavenly bodies.

On October 20, 1868, Lockyer succeeded in observing the solar prominences in broad daylight. Lockyer identified a yellow strip in the spectrum of the sun that conventional scientific opinion of the time held as a known element under extraordinary circumstances. This suggested to him the existence in the sun of an unknown element, which he named helium after Hēlios, the Greek name for the Sun and the Sun god.

His paper detailing those observations arrived at the French Academy of Sciences on the same day as French astronomer Pierre Janssen’s paper. The French government commemorated the event by striking a medal bearing the portraits of the two astronomers for the discovery of helium.

To facilitate the transmission of ideas between scientific disciplines, Lockyer established the general science journal Nature in 1869. He remained its editor until shortly before his death. He died in Salcombe Regis, Devonshire.
Sir Joseph Norman Lockyer (17 May 1836 – 16 August 1920) – British astronomer

Edwin Powell Hubble (1889–1953) - Father of observational cosmology

Edwin's mother was Virginia Lee James, from Virginia City, Nevada, and his father was John Powell Hubble, from Missouri. Edwin himself was born in Marshfield on November 20, 1889, during a visit of the parents to his grandparents and moved to Wheaton, Illinois, before his first birthday.

He studied mathematics and astronomy at the University of Chicago and earned a bachelor of science degree in 1910. In the same year he was awarded a Rhodes Scholarship, under which he read Roman and English Law at Queen's College, Oxford.

In 1914 he returned to the University of Chicago for postgraduate work leading to his doctoral degree in astronomy.

Edwin Hubble was considered as the father of observational cosmology: he showed other galaxies exist beyond the Milky Way using 100-inch telescope at Mt Wilson. He identified individual stars in one of Wright and Kant’s nebulae, one of the largest of them, the “Great Andromeda Nebula”. It has this name because is seen in the sky region where it is located the constellation of Andromeda.

Hubble also developed classification system for galaxies and showed that the Universe is not static Edwin Hubble but expanding.

In 1929 he established the famous distance-velocity relation which is also called nowadays the law of redshift or Hubble’s law. The title of his paper reads: “A relation between distance and radial velocity among extra-galactic nebulae.”
Edwin Powell Hubble (1889–1953) - Father of observational cosmology

Giovanni Domenico Cassini - The first discovered the division in the rings of Saturn

Born on June 8, 1625, in Perinaldo, Republic of Genoa (now Italy), Jean-Dominique Cassini (8 June 1625 – 14 September 1712) was raised and educated in Italy.

Cassini was an astronomer at the Panzano Observatory from 1648 to 1669. He also served as a professor of astronomy at the University of Bologna. Invited by Louis XIV, Cassini moved to Paris in 1669 to head the brand-new Paris Observatory.

With an improved, high powered telescope that he carefully shipped from Italy, Cassini continued a string of astronomical discoveries that made him one of the world’s most famous scientists. The discoveries include the rotation periods of Mars and Saturn, and in 1675, Cassini discovered the gap in Saturn’s rings that now known as the “Cassini Division.” From 1671 to 1674, Giovanni Cassini discovered the moons Iapetus, Rhea, Dione and Tethys.

The distance to the sun has always been regarded as the most important and fundamental of all galactic measurements, Cassini’s 1672 measurements, however, was the first to accurately estimate that distance.

Giovanni Domenico Cassini - The first discovered the division in the rings of Saturn 

Caroline Herschel: The first female comet-hunter

Herschel, Caroline Lucretia (16 March 1750 – 9 January 1848), astronomer, was born at Hanover, the eighth child and fourth daughter of Isaac Herschel (1707–1767) and his wife, Anna Ilse Moritzen.

The Herschels grew up in a musical family in Hanover, and there Caroline was trained to look after her brothers and ageing parents. Her father also encouraged his children to study music, Mathematics and French.

Closer to her father, Caroline recounted that one of her strongest childhood memories was of her father taking her outside on a frosty night and showing her the winter stars 'to make me acquainted with the most beautiful constellations, after we had been gazing at a comet which was then visible'.

Caroline's childhood was overshadowed by the defeat in 1757 of the Hanoverian army by the French in the Seven Years' War and the resulting occupation of Hanover. Her elder brother William, though in the same band as their father, was too young to be under oath, and so was free to flee to England. Caroline joined her brother, William in England in 1772, ostensibly to train as a singer and to accompany him in his concerts. This training was technical in nature, teaching her the mechanics of how to sing and make her voice carry, how to read music and speak English.

William and Caroline often discuss astronomy. Eventually her interest grew in that area and she gave up a promising career as a singer to concentrate on astronomy. Her brother soon found her efficient, meticulously talents essential to his work. She assisted him by his recording his observation astronomical catalogue.

Then in 1781 William discovered the planet Uranus and this gained him a Royal Pension from George III, with the requirement that they should give up music and move near to Windsor Castle. Once there, Caroline began training as an astronomer, learning skills she was expected to put to use almost immediately, acting as her brother’s astronomical assistant and scribe.William had built her a telescope expressly designed for the discovery of comets.

Caroline was to become famous as the discoverer, or co-discoverer, of no fewer than eight comets, four with the sweeper made in 1783, three with its successor, and the last, found in 1797, with the naked eye. However, her earliest sweeps, in the winter of 1782–3, yielded not comets but comet-like nebulae, to add to the hundred or so already known. Later in 1783 she was to discover the companion to the Andromeda nebula.

When William died in 1822, Caroline returned home to Germany and continued her astronomical work. She was awarded a gold medal by the Royal Astronomical Society in 1828 and was made an honorary member of the Royal Society ten years later.
Caroline Herschel: The first female comet-hunter

Jamshid al-Kashi of Samarkand

Jamshid al-Kashi of Samarkand (c. 1380 – 22 June 1429) was an Arab mathematician and astronomer. Noteworthy for the accuracy of his computations, especially in connection with the solution of equations by Horner’s method and his practice of using decimal fractions, both of which he derived from the Chinese.

Al-Kashi paid special attention to the method of measuring the parts of edifices and building such as arches, vaults, hollow, cupolas and stalactite surfaces widely wonted in the medieval East.

Calculated correctly π to 16 decimal places, No mathematician approached this accuracy until the late 16th century.

Between the 14th and the 15th century, Al-Kashi wrote the Key to Arithmetic. In this work he calls binomial coefficients “exponent elements”. The book provides a glimpse of the influence of Chinese mathematics.

Al-Kashi found patron in the prince Ulugh Beg, grandson of the Mongol conqueror Tamerlane. At Samarkand, where he held his court, Ulugh Beg had built an observatory in 1428 and al-Kashi joined the group of scientist gathered there.
Jamshid al-Kashi of Samarkand

American astronomer: Carolyn Shoemaker

Carolyn Shoemaker is an observational planetary astronomer who has discovered more than 30 comets and 800 asteroids, more than any other astronomer. She was one of the co-discoverers of the comet Shoemaker-Levy 9 that collided with Jupiter and split apart in 1992.

Carolyn Jean Spellman Shoemaker was born June 24, 1929 in Gallup, New Mexico. She received a bachelor’s degree from Chico State College in California in 1949 and a master’s degree in history and political science in 1950.

After a spell as a schoolteacher, she married the astrogeologist Gene Shoemaker in 1951, and settled down eventually in Flagstaff, Arizona.

Since 1980, Shoemaker has been a visiting scientist at the US Geological Survey’s Center for Astrogeology in Flagstaff, Arizona, where her husband was a founding director.

In 1993 the husband and wife team, working with David Levy, discovered the comet Shoemaker-Levy 9. This achieved international prominence when its remnants collided with Jupiter in 1994, a rare event witnessed by astronomers around the world, and by the Voyager 2 spacecraft.
American astronomer: Carolyn Shoemaker

Al-Khāzini

Abu al-Fath Abd al-Rahman Mansour al-Khāzini (1115-1130) or simply Abu Al-Fath Al-Khāzini was a Muslim of Greek origin who was brought to Merv as a slave by the Seljuk king after his victory over the Byzantine Emperor.

He was the pupil of Umar Khayyam. His master is responsible for his education in mathematics and philosophy.

Al-Khāzini was a great physicist, astronomer, mathematician, philosopher and alchemist. He is better known for his contribution to physics. He is one of the few Islamic astronomers to be known for doing original observation.

His treatise: Al-Khāzini’s Kitab mizan al-hikma written in four volumes, remained an important part of physics among the Muslim scientists. It is a treatise on the physical principles that underline the hydrostatic balance as well as the construction and use o the instrument.

As an astronomer his main work is his Al-Zij al-Sanjari, an astronomical handbook with tables, compile between ca. 1118 – ca 1131 and dedicated to the Seljuk Sultan Sanjar ibn Malikshah.
Al-Khāzini

Snellius Willebrord

Snellius Willebrord (13 June 1580 – 30 October 1626) was a famulus of Tycho Brahe in Prague 1600 and went on to become one of the leading mathematicians of the early seventeenth century.

Snellius Willebrord was born 1580 in Leiden, where his father Rudolphus Snellius, was professor of mathematics for thirty years.

Although he studied law at the University of Leiden, he was most interested in mathematics and at age nineteen he received permission to lecture on mathematics and astronomy. Later he succeeded his father as professor of at the university.

Snellius Willebrord

Between 1600 and 1602, he traveled through Europe, pursuing an interest in astronomy, especially at Paris toward the end of his tour.

Snellius is famous for having explained the refraction of light, discovering the sine law, and improving the method for calculating approximate values for π.

Based in research begun in 1615, he published in 1617 his Eratostheses Batavus, a work advancing his method for measuring the size of the earth through the use of triangulation, concept first proposed by the sixteenth-century scientist Tycho Brahe.
Snellius Willebrord

William Herschel (1738-1822)

Among the astronomical luminaries of the 18th century none shone as brightly as William Herschel. William Herschel was born on 15 November 1738, the fourth of ten children born to Isaac and Anna Herschel in Hanover, Germany.

In 1750s Isaac and his son William and Jacob were engaged as musicians in the Hanoverian Guards. In 1756 he toured England for several months with his father and the Guard. The country and cultures left a lasting impression on the young composer, and in the autumn of 1757 William left Germany for England where he lived for the rest of his life.

William Herschel

An early interest in the stars had blossomed by 1773, when Herschel began acquiring books on mathematics to help him with harmony to improve his music. His interests quickly spread from mathematics to astronomy.

About this time he began to rent small telescopes to observe the heavens and also started his first rudimentary attempts at constructing telescopes.

On a spring night in 1781 William Herschel was surveying the night sky with his 7-ft telescope with a 6-in mirror. He spotted an object that appeared to have an odd shape, slightly different from the shape of the star. The name of the planet later became Uranus after a suggestion by German astronomer, Johann Bode.

William Herschel directed his tremendous energy towards making many observations of a much higher quality than anyone had one before. He made catalogues of nebulas and double stars and discovered moons around Uranus and Saturn.
William Herschel (1738-1822)

Biography of Thales of Miletus

Diogenes Laertius says that Ionian philosophy began with Anaximander but that Thales instructed Anaximander.  Aristotle considered Thales to be ‘the first founder of this kind of philosophy, for example, the thought of those subject who sought to find what he called the ‘material cause ‘ of things.

Though he was the son of a Phoenician mother, Thales of Miletus was a citizen of the Ionian city of Miletus. Thales’s mother bore the Greek name Cleobulina; his father was called Examyes, a name used by Carians, the indigenous people of southwestern Anatolia.

Thales was born in Miletus, the premier city of Archaic Greece (in modern Turkey). Eventhough little is known about his life, Thales came to be known as the first of the ‘Seven Sages’ or wise men of the ancient world.

He was a founder of the Ionian school in the pre-Socratic Era. Thales was an astronomer, mathematician and philosopher. He was born in 624 BC and died in 565 BC.

Thales established a heritage of searching for knowledge for knowledge’s sake, development of the scientific method, establishment of practical methods and application of a conjectural approach to question of natural phenomena.

Miletus was a seaport on the trade routes that linked the Mediterranean world with India and other countries of the Near East, Ass Thales traveled outside his local community, he became known as Thales of Miletus.

As a young man, he traveled to Egypt and the Near East to study geometry, a branch of mathematics concerned with points, lines and surfaces in two dimensions. He learned how Egyptians used practical geometrical techniques to measure distances and to calculate areas of plots of farmland.

Thales learned astronomy from Chaldaeans at Babylon. He learned of the ‘Saronic cycle’ that is to say the interval of eighteen years and eleven days, a multiple of which the observation of ages by temple star-gazers had shown to be usual between eclipses of the sun. Knowledge of this enabled the shrewd travel to make a lucky forecast of the eclipse visible at Miletus in 585 BC.

It was Thales of Miletus, who was credited with the discovery of the electrostatic attraction. Thales noted that after amber was rubbed, straw was attracted to the piece of amber.

The Neo-Platonist philosopher Proclus, writing in the fifth century AD, says that Thales learned geometry from the Egyptian and brought the knowledge back to Greece. Thales is noted for his contributions in geometry and cosmology.

Thales was also supposed to be the first to prove various geometrical theorems and it was said that he used geometry to measure the heights of the pyramids in Egypt and the distance of ships at sea.

Aristotle claimed Thales as the first person to propose natural, rather than mythical, causes for the creation of the ‘kosmos’ or world. In developing a rational theory of the kosmos, Thales asserted that water was the first principal; that is water is the material cause of all things.
Biography of Thales of Miletus 

Ernst Florens Friedrich Chladni (30 November 1756 – 3 April 1827)

Ernst Florens Friedrich Chladni was born in Witten berg, Germany. He was the only child of Ernst Marin and Johanna Sophia Chladni. His grandfather was a prominent Lutheran theologian and his father a distinguished jurist.

Although he was educated by his parents in a strict, rather isolated household, Chladni developed a yearning for travel and a strong interest in the natural history of the Earth and the heaven.

Chladni studied law at the universities of Leipzig and Wittenberg, receiving his doctorate at the later institution in 1782, the year of his father’s death. Chladni immediately abandoned law and remained at Wittenberg a few years to study mathematics and science.

One of Chladni’s best-known achievements was inventing a technique to show the various modes of vibration on a metallic surface.

In 1787 he published his Entdeckungen über die Theorie des Klanges (Discoveries in the Theory of Sound), consisting a drawing a bow over a piece of metal whose surface was lightly covered with sand. This plate was bowed until it reached resonance and the sand formed a pattern showing the nodal regions.

In late 1792 and early 1793, Chladni visited Gottingen to demonstrate his newly invented keyboard instrument, the euphonium and had the opportunity to talk for many hours with Lichtenberg.

Chladni was one of the first scientists to be believe that meteorites fell from the sky but his opinion was treated with disdain until Jean Baptiste Biot proved him to be correct in 1803.
Ernst Florens Friedrich Chladni (30 November 1756 – 3 April 1827)

Brahmagupta

Brahmagupta is a renowned astronomer and mathematician of the seventh century. It was he who taught the Arabs astronomy before they became acquainted with Ptolemy.

Brahmagupta was born in Ujjain, India in 598 AD. Brahmagupta worked in the great astronomical center of Hindu science, Ujjain, a town in the state o Gwalior, Central India, said to have been the vice-regal seat of Asoka during his father reign at Patna.

His famous text Brahmasphutasiddhanta (The opening of the universe). Brahmasphutasiddhanta is Brahmagupta most important work. It is a standard treatise on ancient India astronomy. 

Brahmasphutasiddhanta composed in 628 Ad contains twenty five chapters including Dhyanagrahopadesadhyaya, is also observed by Al-Biruni – Muslim scholar and polymath of the 11th century.

The first 10 chapters pertain solely to astronomy, discussing the longitude of the planets, lunar and solar and solar eclipses and the timing alignments.

Chapter 7 is on mathematics. It deals with elementary arithmetic, algebra and geometry.

Brahmagupta goes on to describe the decimal place value system use in India. He permits zero as a valid number in all of his computations.

Brahmagupta genius made use of mathematics in providing better astronomical methods.

George Sarton, the founder of the disciple of historian of science called him ‘one of the greatest scientist of his race and the greatest of his time’. He died in 665 AD
Brahmagupta