Evolution of Research in Different Astronomies in India

Indian Journal of Radio & Space Physics Vol. 15, October & December 1986, pp. 375-380

J C BHATTACHARYYA Indian Institute of Astrophysics. Bangalore 560034

The evolution of astronomical studies is reviewed with special reference to important achievements on Indian soil since the introduction of telescopic observations in the early seventeenth century. Important activities in nineteenth and early twentieth century in theoretical and observational astronomy have been covered. The growth of non-optical methods of observations and their applications by scientists in India have been briefly described. The paper also summarizes the present state of astronomical research in the country.

Astronomy is a very old science. In fact it arose from a (ii) Angular magnification and resolution. It enabled series·ofthe oldest questions that the human mind was astronomers to see many more faint objects and to confronted with in trying to understand Nature. The study brighter objects in detail-a feat which was not incisive logical thinking to understand the seasonal possible with the older instruments. Optical telescopes changes of the sun, the waxing and waning phases of were first used on the Indian soil a few decades earlier the moon, the regular pattern of movements of the to the magnificent endeavour of Jai Singh. Earliest planets, the nature of the star-studded deep dark skies, reference dates back to 1689 when Father Richaud, a has been helpful in building up the edifice of present Jesuit Priest at Pondicherry, discovered a comet knowledge in the field. through a telescope. He also discovered that the India has been a seat oflearning over the ages. Along southern bright star, alpha-centauri, was in fact a with other branches of natural philosophy, pondering double star. over the science of celestial objects had engaged the Chronologically the next important event describes attention of our ancient sages. In this paper, instead of th~ use of a small optical telescope by William Petrie, tracing the ancient history, including the golden age of an East India Company official, for the determination Indian science between the fifth and twelfth century of latitude and longitude of a few places in Southern A.D., I shall deal only with the happenings in more India in 1786. Three years later Madras Observatory recent times; starting with the introduction of new was established by the East India Company with the techniques in astronomy which came from Europe. same set of instruments donated by Mr Petrie. A Introduction of telescopes, in fact, overlapped with proper observatory building came up in 1792; from the older methods of observation in India. A then onwards regular records of observations in the magnificent example of old instrumentation can be form of Annual Reports of Madras Observatory are seen in the heart of our present day capital city of New carefully preserved. Delhi. Jantar Mantar, as it is popularly known, is one Scientists at the observatory achieved several of the five observatories set up by Raja Sawai Jai Singh important discoveries during the next hundred years. of Jaipur. The entire structure and instrumentation is Mention may be made of compilation of a star atlas by of brick masonry, the angular accuracy of position Taylor and discovery of five asteroids and variable determination resting solely on the enormity of their nature of several stars by Pogson. It was also during dimensions. But the principle of optical imaging this period when Chintamani Raghunathachary discovered the variable nature of the star RR Reticuli. rendered such huge structures unnecessary; better accuracies were possible with telescopes of much He appears to be the first Indian astronomer on record smaller dimensions. Thus the huge instruments of Jai to publish a scientific paper on astronomy using modern instruments. Singh's observatory became obsolete as a result of development of science. Three more observatories at Lucknow, Poona and· Besides providing more accurate positional Trivandrum were also functioning during the measures, the optical telescopes provided two distinct nineteenth century. They also employed current types advantages, viz. (i) Intensification of the images, and of equipment prevalent at that time. Lucknow

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observatory was patronized by the Nawab of Oudh is a memorable one and is often referred t.oas the event and functioned under the directorship of Wilcox. The heralding the birth of the subject of astrophysics, observat.ory, h.owever,was cl.oseddawn after the death because, during this eclipse tw.o teams l.ocated at tw.o .of Wilc.ox in 1849, and the astr.on.omical activities places in present day Andhra Pradesh disc.overed a c.ould n.ot be revived. Trivadrum .observat.ory was yell.owline in the chr.om.ospheric spectra which c.ould similarly patronized by the Maharaja .of Travanc.ore• n.ot be due t.o any kn.own element. Sir N.orman C.ochin and was started in 1837. Broun wh.o was in L.ockyear named this as Helium-the element .on the charge maintained the basic activities, but his pers.onal sun. It was years later when this was disc.overed by interest was in ge.omagnetism. His main disc.overy is Ramsay .onthe earth as a decay pr.oduct.of radi.oactive n.ow hailed as .one .of the fundamental principles .of elements. This was the first instance when inf.ormati.on ge.omagnetism, that magnetic disturbances .on earth ab.out physical c.onditi.ons .on an inaccessible celestial are n.ot l.ocalized but are w.orldwide phen.omena. This s.ourcec.ouldbe .obtained. This abservati.on had set the .observat.ory has, till t.oday, remained in a d.ormant trend far .observati.ons in future eclipses. farm with sp.oradic attempts t.o revive the activities The 1871 eclipse was als.o fruitful when the from time t.o time. celebrated French astron.omer Jansen disc.overed what The .observat.ory in P.o.oua was less f.ortunate in is knawn as the F-c.orona. The 1898 eclipse is having a s.ource .of similar regular financial supp.ort. mem.orable .on tw.o c.ounts: it was during this eclipse The guiding farce behind the activities was Prof. that a British team .obtained the first ultravi.olet Kawasji Naegamvala, a Profess.or .of Physics at the extensian .of chram.ospheric spectra. Jahn Evershed, Elphinst.one C.ollege in B.ombay, wh.o used t.o c.ollect wha was a member .of the team, had his first visit ta d.onati.ons t.o run the .observat.ory. One .of the chief India, where later, he was t.oplaya very imp.ortant role d.on.orswas Maharaja Takhtsinghji .ofBhavnagar wh.o in astronamical achievements. Sec.ondly,it was during c.ontributed the nucleus .ofa fund fr.om which a 20-in this eclipse when Naegamvala successfully .organized reflect.or telesc.opewas purchased and installed. After setting up.of an abservati.on camp and .obtained results the death .of Naegamvala, the s.ource .of funding .of imp.ortance. This was perhaps the first c.ompletely c.ompletely dried up and the .observat.ory was cl.osed independent Indian eff.ort far an eclipse expediti.on. dawn in 1912. The 20-in telescape was sent ta The dawn .ofthe twentieth century in India saw same K.odaikanal, where it lay packed in baxes, until Dr new activities in the field .of astronamica1 in• A.K. Das set it up in the early fifties. Then, this became vestigati.ons. Tw.o new abservataries, .one at the largest .operati.onal.optical telescape in the c.ountry, Kadaikanal an a 8000 ft high peak near Madurai and and was used in the Internatianal Mars Observati.onal the secand .one at Begumpet, in the .outskirts .of the Pr.ogram 1954-55. After M.K. Vainu Bappu t.oak .o,ver twin city .of Hyderabad-Secunderabad, were estab• charge .of the abservat.ory, he made maj.or lished. First impartant results came from Kadaikanal, m.odificati.onsin its f.ocal plane instrumentatian, and where Jahn Evershed discavered a very impartant put this inta regular .observati.onal pr.ogrammes. Twa feature .of salar physics. In 1909, from precise .of his students gat their dact.orate thraugh spectroscapic investigatians he discavered a syste• .observati.onalmaterial callected by this telescape. Still matic flaw .of material around sunspats. This is the later, Kadaikanal Observat.ory was transfarmed inta fam.ous "Evershed Effect", which has engaged the an autanamaus research institute, and a new attentian .ofscientists since that time, and which later abservatary was established at Kavalur, where this has develaped inta the subject .ofsalar magnetahydro• telesc.ope was shifted. Its impartance at Kavalur, dynamics .of taday. hawever, was avershadawed by larger telescapes Nizamiah Observatary at Begumpet, after its which were installed subsequently. At the present establishment, entered inta an internatianal pro• mament, this telescape has been installed at Lch, in the gramme in pasitianal astranamy abservatians. The Laddakh regian .of Kashmir, where a temparary abservatary jained the ''Carte du Ciel" programme .of abservatary has been set up ta assess the suitability .of mapping part .ofthe celestial sphere. The abservatary this place far a future high altitude astranamical prepared a catalague .of 800000 stars, listing their statian. accurate pasitians and magnitudes, which has proved Bef.oreI mave aver ta the narratian .ofmuch mare invaluable in astronamical investigatians .of taday. camprehensive astr.onamical activities .of the present Very .oftenwe hear .ofnew saurces in radia, infrared .or century, I must mentian three impartant salar eclipses ultravialet regians discavered by madern techniques whase paths .of tatality crossed aver India in the later which are ultimately tied dawn ta same faint stellar half .of the nineteenth century. All the three events saurces from the .old catalagues; several .of them in brought in new infarmatian in astranamy. The three recent times have been traced ta the stars listed in the events taak place in 1868, 1871and 1898.The first .one Hyderabad catalague.

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BHATTACHARYYA:EVOLUTION OF RESEARCH IN DIFFERENT ASTRONOMIES IN INDIA

Meanwhile, a rather rare celestial phenomenon played on a low key. Except for some solar research at kindled the interest of the intelligentsia which resulted Kodaikanal, and the Nizamiah Observatory's work in in the formation of the first Astronomical Society of the "Carte du Ciel" programme no outstanding India with its headquarters in Calcutta in 1910. I am observational work was pursued. The wind of change referring to the apparition of Comet Halley in that came towards the end of the second world war; the year. The society encouraged astronomical obser• person responsible was again, Saha, who persuaded vations and started. a journal. The enthusiasm, the Government ofIndia into action. A committee was however, could not be maintained for long and no set up to draw up a co-ordinated plan under his issues of thejournal appeared after 1921. But during its Chairmanship; the report was the document on which brief existence, the issues of the journal contained the development plans in astronomy were hinged for scientific articles written by leading physicists of the the next thirty-five years. Only recently, realizing the time, like C.V. Raman and M.N. Saha. tremendous advancement achieved in the field, Any description of the evolution of astronomy in attempts have been made to define new thrust areas in India will remain incomplete without"reference to the different branches of astronomy. enterprising exploits of Meghnad Saha during this Saha's recommendations covered both teaching and epoch. Calcutta, at that time, did not have any regular research. Along with the development of observa• astronomical observatory. Two colleges, S1. Xaviers tories, a strong plea was made for starting new and Presidency had small telescopes, but no regular departments of astronomy in the universities. The programmes of investigation, and yet, one of the implementation of the latter recommendation has not greatest puzzles in astronomy at that time was solved been very fast, but not altogether disappointing; today, by a young scientist, working solely on the basis of his as many as 22 universities in the country teach deep insight into the physical processes occurring in astronomy in some form in their post-graduate classes. the outer layers of stars. Eddington had listed Saha's Saha's recommendations mainly concerned optical work on ionization theory as one of the ten most astronomy; but outside the committee's deliberations important findings in astronomy since the in• he made valiant attempts to start several other new troduction of telescopes by Galileo. branches using radio, particle and ultraviolet Saha was basically a theorist, and most of the techniques. I shall mention these briefly at the important work in astronomy was centred around his appropriate points of context. laboratory at Allahabad University. Some front The period after independence has witnessed ranking results of theoretical astrophysics were tremendous changes in activitieti in optical astronomy, reported in the thirties by his students; mention may be and the pivotal role was played by a young scientist, made of some of the original work on stellar interiors Late Dr M.K.V. Bappu. He almost grew up in an and on degenerate cores of white dwarfs by D.S. observatory, his father being an astronomer at Kothari, R.C. Majumdar and others. Saha had dreamt Nizamiah Observatory. He was an amateur astro• of setting up of a leading centre in Laboratory nomer at school, adopted astronomy as his profession Astrophysics in Allahabad, but the rapid advancement and later became a colossus in the history of Indian of scientific measurement technology in other .astronomy. After his master's degree from the Madras developed countries, coupled with lack of adequate University he chose a course of astronomy at Harvard financial support for science by the state frustrated his and returned to India after a couple of years' post• plans. doctoral work in various institutions in the US. His Two more centres of theoretical studies grew up first contribution was in finalizing plans for a 48-in during the thirties at other places. The first was in telescope for the Osmania University; next, he moved Calcutta led by Prof. N.R. Sen and second by Prof. over to Banaras, and established a new modern V.V. Narlikar at the Banaras Hindu University. observatory at Nainital and then moved over to Einstein's theory of relativity had brought in a new Kodaikanal. Within a few years he established a most look at the physical happenings in the universe, and modern observatory at Kavalur. He was barely 28 both the teams engaged themselves in solving years of age when he established the Nainital questions in relativity and cosmology. Some brilliant Observatory. At the age of 32 years, he was the pieces of original work emerged out of these youngest Director of the Kodaikanal Observatory. He endeavours; mention may be made of solution for had set the Kavalur Observa tory moving before he was gravitational collapse of spherical dust clouds by B.B. forty. He was unanimously elected as the President of Datt and of rotating cosmological model by A.K. Ray the International Astronomical Union: he headed this Chaudhuri in Calcutta, and solutions of a radiating world body till his premature death at the age of 55. mass by P.c. Vaidya at Banaras. Bappu introduced many new ideas in observational All these years, the observational astronomy was astronomy in India. He had brought with him essential

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components needed to build photoelectric photo• recording of transient events which earned the credit of meters and started photoelectric photometry with the new discoveries of unknown ring structures around the available telescopes. He built a spectrograph and planets Uranus and Saturn. For the first time in the attached the same to the old 20-in telescope at present age, observations in India unfolded new Kodaikanal. He built a photoelectric scanner for direct discoveries. These definitely represented a welcome measurement of stellar spectra and modified it later for departure from the era when Indian astronomers had the introduction of the first computer-controlled to play second fiddle in observational ventures. Similar spectrum scanner in the country. growth in observational facilities was also noticed in Within the limited funds which could be spared for other optical observations. astronomy, Bappu ordered a moderate-sized but So far I have dealt with only optical astronomy, but highly versatile telescope from Mis Carl Zeiss. UP there are good reasons for this. Asfronomy using other State Observatory at Nainital, which was originally forms of radiation came into existence quite late in started by Bappu, decided to repeat the order. This was human history. This is illustrated in Table 1. From the met from the Uttar Pradesh State funds for scientific earliest times of human civilization until quite recently, research, perhaps the only State in India to show such the only detector available was the unaided human eye. lllterest in basic research. Both the telescopes were New forms of radiation and development of their almost simultaneously installed early in 1972. These detectors have been recent phenomena. two instruments are highly reliable ones and have Greatest advancement in non-optical methods of many a time played a frontal role in observational observation has been achieved in the field of radio astronomy. astronomy. It was Prof. Saha in the early fifties who At Kavalur, Bappu incorporated several auxiliary dreamt of taking a lead in this field. Young workers in instruments, in which some of the vital components of large numbers were attracted to this new subject, his own design figured prominently. He brought in the which had started producing unexpected bits of first on-line computer in optical astronomy in India; information about the universe. Experimental the use of which accomplished several new types of ventures were considerably helped by availability of observations. One of them consists of fast-light-curve- war-surplus stocks of electronic equipment at very low

Table I-Development of Astronomical Techniques: A Chronology of Events Year Event Significance 1610 Galileo begins telescopic observations Limits of detection by human eye extended 1668 Newton builds first reflector telescope Possibility of large instruments later opened 1789 William Herschel builds 48-in telescope Beginning of large instruments 1800 William Herschel detects infrared radiation in solar spectra Discovery of infrared 1801 Ritter detects ultraviolet radiation in sunlight Discovery of ultraviolet 1840 Draper takes first photograph of the moon Introduction of photography 1850 First stars photographed (Vega & Castor) First stellar photography 1888 Hertz generates and detects radio waves Discovery of radio waves 1891 Spectroheliograph invented Systematic study of solar astrophysics 1894 J.e. Bose demonstrates experiments on millimetre waves Millimetre wave techniques developed 1896 Roentgen discovers X-rays New tool for high energy astrophysics available 1901 Rutherford discovers y-rays Another new tool for high energy astrophysics available 1912 Hess proves extra terrestrial origin of cosmic rays Cosmic ray astronomy begins 1917 100-in Hooker n,flector at Mt Wilson' Era of large modern telescopes begins 1932 Jansky detects extra terrestrial radio waves Birth of radio astronomy 1937 Saha describes his idea of space observatory Conception of space astronomy 1939 Hetzler detects infrared radiation from cool stars by special Infrared photometry technique becomes operational photographic emulsions 1946 First scientific payload launched by rocket Birth of space astronomy; ultraviolet experiments 1948 20G-in telescope completed at Mt Palomar Telescope aperture crosses 5m target 1955 Jodrell Bank radio dish commissioned First large steerable radio dish 1957 Sputnik I launched Satellite era begins 1959 Lunokhod Russian probes unveil first picture of the farside First successful space probe of moon 1962 Mariner 2 surveys Venus First successful planetary probe 1962 Scorpio X-ray source detected Birth of X-ray astronomy 1968 Solar neutrino observations undertaken Birth of neutrino astronomy 1969 y-Ray source detected Birth of y-ray astronomy 1976 234-in telescope completed at Zelenchukskaya Telescope aperture reaches 6m target

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\ prices, which encouraged several groups to undertake ray emission. Simultaneous ground based optical and new instrumentation. Subsequently most of them went infrared observations are also being taken to obtain abroad and worked with leading groups at different data for complete analysis; several collaborative parts of the world. It was the foresight of Homi Bhabha programmes are in progress. As the amount of X-ray who lured a sizable group of them back to India and data from Indian instruments are insufficient, some of thus created the radio astronomy group at Ooty. V. these collaborations presently include teams of Radhakrishnan came back to India in 1972, and built scientists working at foreign institutions. independently another powerful group around him at We have at least two groups in India doing Bangalore. He amalgamated the active instrumen• experiments in gamma-ray astronomy. Both use the tation group of Indian Institute of Astrophysics (IIA) method of Cerenkov light flashes in our atmosphere in a joint instrumentation venture. The group at the when gamma ray photons interact. First is the TIFR Physical Research Laboratory (PRL) collected by group, whose main experimental centre is at Ooty, and Vikram Sarabhai was basically oriented towards the second one is the DAE (Department of Atomic aeronomy and adopted radio astronomy techniques in Energy) group at Srinagar. Both the ventures are only investigations of interplanetary medium. Radio a few years old. astronothy experiments at the frontiers of this No experimental work in ultraviolet astronomy has discipline are now done by the three instruments at been done in India. There are several theoretical Ooty, Gauribidanur and Bangalore. investigators who get all the data from foreign sources Another branch of astronomy which has attracted like IDE. attention is the infrared (IR). Experiments in There are other branches of astronomy in which photographic IR started at Kodaikanal in sixties and information contained in particle streams has been later on in the near infrared range at PRL, closely made use of. A few varieties of particles are included in followed by scientists at the Tata Institute of these studies, of which the major ones are.cosmic rays, Fundamental Research (TIFR). They built up IR solar wind and neutrinos. Even though cosmic rays photometers employing cooled PbS and InSb were discovered more than seventy years ago, their detectors and employed them at the focal plane of origin is still shrouded in mystery. Various theories optical telescopes at Kavalur, Rangapur and Nainital. seeking to explain their sources and acceleration PRL is planning extension of the observation band mechanisms have been put forth, but they have not from the existing 1-3 to 8-12 tim, using liquid He• been found entirely satisfactory. There are several cooled, germanium-doped bolometer detectors and groups in India which are engaged in these studies, of employing a new 122-cm telescope with vibrating which the T1FR group is the most active. They have secondary. The telescope is in the final stages of recently flown an experiment "Anuradha'" on the fabrication and expected to be installed at a new space shuttle which was built by joint efforts of a few observatory at Gurusikhar near Mount Abu shortly. institutions in India. Considerable interest exists for observation of IR Interest in cosmic rays was very high from the early around 100tim, which can only be done from satellites, days. After the nature of cosmic origin was proved rockets or very high-flying balloons. The IR group at early in the second decade of this century, India has TIFR, Bombay, had built up a balloon-borne IR undertaken many experiments on cosmic rays. The instrument, which, unfortunately was lost after a earliest one perhaps was in 1926 when Arthur successful flight. A second improved instrument has Compton of the University of Chicago collaborated been built and is expected to be used for a series of with P.L. Bhatnagar of the University of Punjab at launches. Lahore in setting up an equipment on a lake 17000 ft The next branch in order of interest is the X-ray high in Kashmir. Saha was the first to start cloud astronomy. Two groups in India, TIFR and ISSC chamber work at the Palit Laboratory in Calcutta in (Indian Scientific Satellite Centre), Bangalore are 1938and later start a high altitude observing station at doing these experiments. The earliest experiment was Darjeeling. In 1956,just prior to his untimely death, he performed in 1968. when a four-channel X-ray drew up an elaborate plan for cosmic ray research in proportional counter payload was launched in rockets which a station at 16000 ft on the Darjeeling-Lhasa to detect X-ray sources. India's first satellite road was proposed to be set up. But the plan did not Aryabhata contained similar payloads. Harder materialize. components of X-rays were also detected by balloon• In the early fifties, cosmic ray research in different borne hard X-ray detectors. physical laboratories was widespread where attempts Interest in this field is more widespread. Groups of to deduce the nature of primary cosmic rays from theoreticians from several institutes and universities measurements of secondary particles were made. The are busy modelling the structure and mechanism for X- dawn of space age in the late fifties changed the

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situation completely. It became now possible to in Banaras. In course of time scientists from these directly measure primary cosmic rays from satellite• groups dispersed all over India and generated new borne detectors, making ground-based measurements schools at various institutions. obsolete. Only experiments like "Anuradha" remained Saha's original papers were about thermodynamics relevant. of stellar atmosphere; some of his students who continued in this direction were P.L. Bhatnagar, H.K. Emanations from the sun during disturbed periods Sen and A.C. Banerjee. S. Chandrasekhar did were known for quite some time. but the steady solar monumental work on radiative transfer problem; he wind was detected only in the space age. All did not return to India, but sent several of his Indian experiments require satellite payloads, and have since students back to continue theoretical work. Many of been the exclusive concern of space programmes of the the existing theoretical astronomy groups are centred developed countries. Large number of scientists around such scientists at various institutions. interested in the study of solar wind obtain their I have described, very briefly, the course of experimental data from such sources. evolution of astronomical studies in India in our times. Experiments in neutrino astronomy have not yet At this moment, India is poised for a big leap forward. been done in real sense in India. Among the existing Several large observing instruments have been set up; problems are the solar neutrino anomaly and the still bigger ones are coming up. Interest and confidence missing mass of the galaxy, on which some theoretical in areas of astronomical research are very high. There investigations have been made. is a concerted move to expand astronomy teaching The story of evolution of astronomy in India will be facilities in universities to draw more talent to this incomplete without mention of vast amount of the branch. Intrinsically. astronomy has a romantic appeal high theoretical work that has been done in the past to young minds; in the past, in the absence of a proper and is being continued at present. The earliest example atmosphere, we have lost several brilliant minds to is the immortal series of papers by Prof. Saha, and later other institutions abroad, who could have brought by his students in Allahabad, namely, D.S. Kothari, back the ancient glory of India in cosmical sciences. R.C. Majumdar and others. The Allahabad group was That did not happen then, but we have the situation concerned about stellar interiors, while questions in considerably altered now. We may hopefully look relativity and cosmology were being tackled by N.R. forward to a very brilliant period of Indian astronomy Sen and his associates in·Calcutta, and V.V. Narlikar in near future.

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