ANDERS JONAS ANGSTROM

Swedish Physicist and Astronomer

Angstrom was born in Logdo, Sweden in 1814. He studied and taught in the University of Uppasala. He obtained his doctorate (1839) and became Professor of Physics in 1858 at the University and he stayed there until his death in 1874.

His most important work was 'Optical Investigations' (1853) in which he published measurements on atomic spectra, particularly on electric spark.

Having established the principles of spectroscopy in the laboratory, Angstrom turned his attention to the Sun's spectrum, he published in 1968, 'Researches on the Solar Spectrum'. In this, he made the inference that hydrogen was present in Sun. Since 1905 his name has been officially honoured as a unit of length used by spectroscopists and microscopists.

ANAXIMANDER OF MILETUS

Greek philosopher and astronomer

Little is known about his life. He was the pupil of Thales. His writings are now lost, but he is credited with variety of novel ideas. He was the first Greek to use sundial, and with it found the dates of the two solstices(shortest and longest days) and of the equinoxes(the two annual occasions when day and night are equal).

He speculates in the nature of the heavens and on the origin of the earth and of man. Realizing that earth's surface was curved, he believed it to be cylindrical( with its axis east to west); and he was probably the first Greek to map the whole known world.

GIOVANNI BATTISTA AMICI

Italian Astronomer

Amici was born in Modena, Italy in 1786. He studied and graduated as an engineer in Bologna in 1807 and served as Professor of Mathematics are at the university of Modena. He became then as Professor of Astronomy and director of the Royal Museum observatory at Florence.

He made improvements in the mirrors of reflecting telescopes and also developed prisms for use in refracting spectroscopes. He used a hemispheric objective lens to get the first clear microscopic view in 1837, with magnifications as large as 6000 times.

He also invented a combination of three prisms that is still used in spectroscopy and is known as the 'Amici prism'. He observed Jupiter's satellites by making improvements in the reflecting telescope. He made accurate measurements of the polar and equatorial diameters of the Sun, using his own design of micrometer.

ABD AL-RAHMAN AL-SUFI

Persian Astronomer

Little detail is known about the birth and life of Al-Sufi. But it has been established that he was a noble man, whose love of his country's folklore and mythology and interest in mathematics led him to the study of astronomy.

His importance lies in his compilation of a valuable catalogue of 1018 stars with their approximate positions, magnitude and colours.

RALPH ASHER ALPHER

American Scientist

Alpher, the son of a building contractor, was born in Washington D.C. In 1921. His initial interest in science was stimulated by his English teacher, Matlide Eiker, who was also an amateur astronomer. Alpher was studied at George Washington University, received his B.Sc. in 1943 and got his Ph.D. in 1948. His Ph.D. research topic was nuclei synthesis in a Big Bang universe, which was carried out under the supervision of George Gamow. After the World War ll, he joined Applied Physics Laboratory of Johns Hopkins University. Here he worked in varied research programme that, besides cosmology, included cosmic ray physics and guided missile aerodynamics.

Alpher worked with George Gamow and Robert Herman on a series of papers that sought to explain physical aspects of the Big Bang theory of the universe. In 1948 Alpher and Gamow published the results of their work on nucleosynthesis in the early universe. Also in 1948, Alpher together with his colleague Robert Herman, predicted the existence of the pervasive relic cosmic blackbody radiation. This primordial radiation was detected by Arno A. Penzias and Robert W. Wilson in 1965 and was found to have a temperature of 3 K.

The existence of this low temperature radiation that permeates the entire universe is now regarded as one of the major pieces of evidence for the validity of the Big Bang model of the universe, thus Alpher's early cosmological work has had a profound impact towards our understanding of the nature of the universe.

ABU JAFAR MOHAMMAD IBN MUSA AL-KHWARIZMI

Arab Mathematician, Astronomer and Geographer

He was  a member of the academy  of sciences in Baghdad, which flourished during the rule of Caliph alma'mum. He mainly contributed on astronomy and algebra  in mathematics. The algebra enlarged upon the work of Diophantus and is largely concerned with methods for solving practical  computational problems rather than algebra as the term is now understood. Al-Khwarizmi confined his discussion to equations of the first and second degrees.

         His other works are a treatise on the Hindu system of numerals and treatise on geography. Al-Khwarizmi was the first Arab mathematician to expound the new number system systematically. His famous astronomical work, zij-al-sind-hind was based on other  scientists work.

ROBERT GRANT AITKEN

American Astronomer

Aitken was born in Jackson, California, on 31 December 1864. He took his degree at Williams College, Massachusetts. He taught at Livermore College from 1888, and in 1891 he was made Professor of Mathematics at the University of the Pacific. From 1895 onwards he worked at the Lick Observatory on Mount Hamilton and he stayed there till his retirement in 1935 as Director of the observatory.

Aitken did much to advance knowledge of binary stars that is pairs of stars orbiting about the same point under their mutual gravitational attraction. During the early years of the project he was assisted by W.J. Hussey, and they discovered nearly 4500 new binary systems. He published in 1932 the comprehensive work 'New General Catalogue of Double Stars within 120 degree of the north pole'. He also produced the standard work, 'The Binary Stars' (1918).

Aitken's other famous work was his revision of S.W. Burnham's Catalogue of double stars.

SIR GEORGE BIDDELL AIRY

British Astronomer

Airy was born in Alnwick in the north-east of England. His father was a tax collector. He studied in Colchester School before going to Cambridge University in 1819. He became Lucasion Professor of Mathematics at Cambridge in 1826, and became Plumian Professor of Astronomy after two years. In 1835, he was appointed as Astronomer Royal, a post he held for 46 years. He was awarded the Copley medal and Royal medal by the Royal Society and was its president from 1827 to 1883.

When Airy was director of the Cambridge Observatory, he introduced a much improved system of meridian observations and set the example of reducing them in scale before publishing them.

He re-equipped the observatory, installing an altazimuth for lunar observation in 1847, a new transit circle and 33 cm equatorial telescope in 1859. He also created (a new department) magnetic and meteorological department in 1838, began spectroscopic investigations in 1868 and started keeping a daily record of Sunspots with the Kew observatory heliograph in 1873.

He was also responsible for establishing the border between Canada and United States and later of the Oregon and Maine boundaries.

WALTER SYDNEY ADAMS

American Astronomer

Adams was born in Antioch (now in Turkey) in 1876. He was the son of missionaries working in Syria, who returned to America in 1885. Adams graduated from Dartmouth College and obtained his AM from the University of Chicago in 1900. He started his career as assistant to George Hale in 1901 at Yerkes Observatory. He then moved to Mount Wilson Observatory in 1904 along with Hale. He served there as assistant director (1913-23) and then as director from 1923, until his retirement in 1946.

His early work was mainly concerned with Solar spectroscopy, but he gradually turned to stellar spectroscopy. He showed how it was possible to distinguish between a dwarf and a giant star merely from their spectra. He is however better known for his work on the orbiting companion of Sirius, named Sirius B.

In 1924, Adams succeeded in making the difficult spectroscopic observations and did in fact detect the predicted red shift, which confirmed his own account of Sirius B and provided strong evidence for general relativity.

JOHN COUCH ADAMS

British Astronomer

Adams was born in the small Cornish town of Launceston, where his father was a tenant farmer. He graduated in 1843 from Cambridge University and became Lowndean Professor of Astronomy and Geometry in 1858. In 1860, he was appointed director of the Cambridge Observatory.

His fame rests largely on the dramatic events surrounding the discovery of the planet Neptune in 1846, independently of Leverrier, the French astronomer. Adam's calculations, however, were ignored by Airy until Leverrier had published his own prediction. Later, James Challis and John Herchel were publicly pointed out that Adam's work had priority over Leverrier.

Adams later worked on the perturbations of the planets (1866), and on the secular variation of the mean motion of the Moon (1852), both difficult questions of mathematical astronomy. His scientific papers were published by his brother in two volumes in 1876 and 1901.

GIORGIO ABETTI

Italian Astrophysicist

Abetti was born in Padva on 5 October 1882. He studied at the university of Padva and Rome and obtained his Ph.D. in physical sciences. He was appointed as professor at the University of Florence in 1921 and he remained there until his retirement there until his retirement in 1957. From 1921 to 1952 he was Director of the Arcetri observatory in Florence.

He was a member of the socio Nazionale, the Academy of Lincei in Rome, and the Royal Society of Edinburg and the Royal Astronomical Society in Britain. His research had been in the field of astrophysics, with particular emphasis on the sun. He participated in many expeditions to observe eclipses of the Sun and he also joined in one such expedition to observe eclipses of the Sun and he also joined in one such expedition to Siberia to observe the total solar eclipse on 19 June 1936. He was well known for his influential popular text on the Sun, and he has also written a handbook of astrophysics, published in 1936, and a popular history astronomy, which appeared in 1963.