Johannes Kepler, a German mathematician, astronomer, and astrologer was born on December 27, 1571. He is a prominent personality of 17th century.
He started as a mathematics teacher at a seminary school in Graz and later went onto become an associate of Prince Hans Ulrich von Eggenberg
He works as an assistant to the astronomer Tycho Brahe in Prague, and imperial mathematician to Emperor Rudolf II, Matthias and Ferdinand II.
He was also a mathematics teacher in Linz, and adviser to General Wallenstein
His contribution in the field of optics has led to improvement of refracting telescope (the Keplerian telescope). The telescope was mentioned in the Galileo Galilei and was also a member of the Accademia dei Lincei in Rome.
He has bought new insights in the field of astronomy and astrology. Kepler added religious and spiritual comments to these elements and developed a theory that God has created the world according to a defined plan through the natural light of reason. Kepler has interestingly defined astronomy as “celestial physics” as “an excursion into Aristotle’s Metaphysics” and as “a supplement to Aristotle’s On the Heavens“. The studies by Kepler has changed the definition of astronomy from physical cosmology to universal mathematical physics
- Kepler’s laws of planetary motion (his works based on Astronomia nova, Harmonices Mundi, and Epitome of Copernican Astronomy)
- Kepler conjecture
- Rudolphine Tables
It was believed by previous scientists that all the planets and the sun orbit around the earth. However scientists like Copernicus hypothesized that the earth and other planets orbit the sun. However this theory was rejected by the Church and other prominent personalities. Keplers’ work was highly appreciated by Danish astronomer, Tycho Brahe, who soon realized his potential and didn’t give him compete information about planetary motions. But when Brahe died, Kepler accessed this information with him he could analyze the different speeds and distances of the planet observed at different times. With the available details Kepler formulated the Kepler’s Laws of Planetary Motion. “CBSE Syllabus for Class 11 Physics” covers Kepler’s laws of planetary motion. There are three laws
- Kepler’s First Law- Law of Orbits: The planet orbits around a star (sun in solar system) and follows an elliptical path
- Kepler’s Second Law- Law of Equal Areas: The planet and the star if joined by an imaginary line then they sweep equal area in equal interval of time.
- Kepler’s Third Law- Law of Harmonics or Law of Periods: The Square of revolution time is proportional to the cube of the semi major axis of the elliptical orbit formed.
T2 ∝ a3
Tycho Brahe or Tyge Ottesen Brahe was born on 14 December 1546. He was a Danish nobleman, astronomer and writer. He provided insights to the accurate and comprehensive information to the astronomical and planetary observations.
The observations made by Tycho Brahe were more accurate than many of the scientists of that period. He was a well-known astronomer, astrologer and alchemist who was knowledgeable of the modern astronomy and of the exact empirical facts.
He was from a well-known Dutch family and was provided quality education. He has developed instruments to accurately calculate the distances. He formed Tychonic system which offers benefits of the Copernican system with the philosophical benefits of the Ptolemaic system into model of the universe. According to his theory, Moon is orbiting Earth, the planets is orbiting the Sun and Sun to be orbiting the Earth. He has contributed to the field of astronomy by working without the help of telescope.
King Frederick II has built a research institute in Uraniborg. In this institute, he has developed large astronomical instruments which helped in making astronomical measurements. Tycho developed another underground institute Stjerneborg for developing instruments for more accurate development. King Frederick II has given Tycho an estate on the island of Hven. He was an autocrat on the island and many residents didn’t like him much. He has established many factories such as paper mill, to provide material for printing. Once the Monarch King Frederick II stepped down he couldn’t gel with the new Danish king, Christian IV, in 1597. He later moved to Prague with the invite of the Bohemian king and Holy Roman Emperor Rudolph II. He was the official imperial astronomer and built an observatory at Benátky nad Jizerou. He was assisted by the famous scientist Johannes Kepler, who has introduced three laws of planetary motion using Tycho’s astronomical data. He died in 1601 and all his data was taken by Kepler. It is assumed that Kepler has stolen Tycho’s astronomical data and clubbed together his data and developed the Kepers law and Rudolphine. His body was exhumed twice to examine the cause of his death and also to find the material with which his nose is made.
A lunar crater is named after Tycho Braho in his honour. The bright supernova, SN 1572, is also known as Tycho’s Nova. A Planetarium in Copenhagen is also named after Tycho Brahe.
Nicolaus Copernicus was born on 19 February 1473 in Renaissance era. He has spent his entire life in Royal Prussia which was then part of Kingdom of Poland. Copernicus was master in several languages and a person of wide knowledge or learning. He was doctorate in canon law and was also a mathematician, astronomer, physician, classics scholar, translator, governor, diplomat, and an economist.
He was first mathematician and astronomer who developed the theory that sun is the center of the universe and not earth and all the planets revolve around the sun. Previously all the astronomers use to believe that earth is the center of the universe and al the planets including the sun revolves around the earth. The work of Nicolaus Copernicus was published in his book De revolutionibus orbium coelestium (On the Revolutions of the Celestial Spheres), before his death in 1543. Copernicus’ model had brought scientific revolution and was referred as Copernican Revolution.
He was a renowned economist and worked to develop quantity theory of money. In 1519, he formulated Gresham’s law, an economic principle.
Copernicus’ major work on his heliocentric theory of Commentariolus, or Brief Sketch was copied and circulated in the scientist community. The inventions of Copernicus has been discussed in “CBSE Syllabus for Class 11 Physics”
His book De revolutionibus was divided into six sections or parts
- General vision of the heliocentric theory
- The principles of spherical astronomy and a list of stars (theory)
- Motions of the Sun and to related phenomena
- About Moon and its orbital motions
- Motions in longitude of the non-terrestrial planets
- Motions in latitude of the non-terrestrial planets
The major highlights of heliocentric theory are
- The center for each celestial circles or spheres is different
- Earth is not the center of the universe and the center towards which heavy bodies move and the center of the lunar sphere
- All the planets revolve around the sun and the center of the solar system is near the sun
- The brightness of the planets vary as they are at varying distances from the earth
- The apparent retrograde and direct motion of the planets arises not from their motion but from the earth’s.