F.P. Israel – författare

Around the beginning of the sixteenth century, Portuguese and Dutch sailors first ventured into southern seas. With their keen navigational interest in the skies, they noted the continuous presence of two cloud-like features, not far from the almost immediately Southern Pole. The first literature mention of these ''clouds'' was in the journal written in 1520 by the Italian navigator Pigafetta on the first circumnavigation of the globe by Magalhaes (c/. Pigafetta et ai. , 1962). In honour of this exploit, the objects have since become known as the Magellanic Clouds, although the Dutch name ''Kaapsche Wolken'' (Cape Clouds - after the Cape of Good Hope) has also been in use for centuries. The Large and Small Magellanic Clouds are dwarf irregular galaxies, orbiting our own Milky Way Galaxy, presently at distances of 53 and 63 kpc respectively (Humphreys, 1984) . . They are the galaxies nearest to us: most other Local Group galaxies are of order ten times more distant. The LMC and SMC are also the prototypical blue dwarf irregulars, representatives of a class of objects in which several hundred more distant objects are now known. Their masses are a few per cent of the mass of the Milky Way Galaxy, but they are relatively gas-rich and appear to be, at the present epoch, forming stars at a more prodiguous rate than our Galaxy (c/. Lequeux, 1984).

''Light on Dark Matter'', held from 10-14 June 1985 in the Dutch seaside resort of Noordwijk, was the first international conference devoted to the results of the all-sky survey by the US-Dutch-UK Infra-Red Astronomical Satellite (IRAS). As such, it was a hommage to the scientists, engineers and technicians who conceived, built and operated this extremely successful satellite. That this was generally felt to be the case, was proven by the large number of participants (over 200 from seventeen different nations), the li vely discussions, and the great variety of topics presented during the meeting. All this not withstanding a typical Dutch summer: gale-force winds, heavy cloud cover, and meter-high surf crashing onto a beach on which only the hardy ventur. ed. Most participants contented themselves by watching the lonely seagulls patrolling the North Sea coastline through the panoramic windows of the conference center. Parallel to the IRAS Conference, a Workshop on Infrared Properties of Interstellar Grains was organized by J. M. Greenberg of the Leiden Laboratory Astrophysics Group: a busy shuttling of participants between the Workshop room and the Main Conference Hall showed that many found it hard to choose. A large number of people were invol ved in making the Conference a success: in the first place the scientific organizers with their valuable advice and the conference speakers, among which I would like to mention Dr. J. H.

Problems associated with a general scarcity of observations of the southern sky have persisted since the present era of galactic research began some sixty years ago. In his 1930 Halley Lecture A. S. Eddington commented on the observational support given to J. H. Oort''s theory of galactic rotation by the stellar radial velocities measured by Plaskett o 0 and Pearce: " . . . out of 250 stars only 4 were between 193 and 343 0 galactic longitude [=£1: 225 < £11 < 15~; a stretch of one-third of the whole circuit was unrepresented by a single star. This is the operation which Kapteyn used to describe as "flying with one wing". By mathematical dexterity the required constants of rotation have been extracted from the lopsided data; but no mathematical dexterity can avert the possi­ bility that the neglected part of the sky may spring an unpleasant sur­ prise. As a spectator I watch the achievements of our monopterous avia­ tors with keen enthusiasm; but I confess to a feeling of nervousness when my turn comes to depend on this mode of progression. " During the past few years substantial gains have been made in securing fundamental data on the southern sky. Interpretations based on combined southern and northern surveys are producing a balanced descrip­ tion of galactic morphology. These matters were discussed at a Workshop held at the Leiden Observatory, August 4-6, 1982, attended by some 60 astronomers from 9 countries.

Problems associated with a general scarcity of observations of the southern sky have persisted since the present era of galactic research began some sixty years ago. In his 1930 Halley Lecture A. S. Eddington commented on the observational support given to J. H. Oort's theory of galactic rotation by the stellar radial velocities measured by Plaskett o 0 and Pearce: " . . . out of 250 stars only 4 were between 193 and 343 0 galactic longitude [=£1: 225 < £11 < 15~; a stretch of one-third of the whole circuit was unrepresented by a single star. This is the operation which Kapteyn used to describe as "flying with one wing". By mathematical dexterity the required constants of rotation have been extracted from the lopsided data; but no mathematical dexterity can avert the possi­ bility that the neglected part of the sky may spring an unpleasant sur­ prise. As a spectator I watch the achievements of our monopterous avia­ tors with keen enthusiasm; but I confess to a feeling of nervousness when my turn comes to depend on this mode of progression. " During the past few years substantial gains have been made in securing fundamental data on the southern sky. Interpretations based on combined southern and northern surveys are producing a balanced descrip­ tion of galactic morphology. These matters were discussed at a Workshop held at the Leiden Observatory, August 4-6, 1982, attended by some 60 astronomers from 9 countries.

Around the beginning of the sixteenth century, Portuguese and Dutch sailors first ventured into southern seas. With their keen navigational interest in the skies, they noted the continuous presence of two cloud-like features, not far from the almost immediately Southern Pole. The first literature mention of these 'clouds' was in the journal written in 1520 by the Italian navigator Pigafetta on the first circumnavigation of the globe by Magalhaes (c/. Pigafetta et ai. , 1962). In honour of this exploit, the objects have since become known as the Magellanic Clouds, although the Dutch name 'Kaapsche Wolken' (Cape Clouds - after the Cape of Good Hope) has also been in use for centuries. The Large and Small Magellanic Clouds are dwarf irregular galaxies, orbiting our own Milky Way Galaxy, presently at distances of 53 and 63 kpc respectively (Humphreys, 1984) . . They are the galaxies nearest to us: most other Local Group galaxies are of order ten times more distant. The LMC and SMC are also the prototypical blue dwarf irregulars, representatives of a class of objects in which several hundred more distant objects are now known. Their masses are a few per cent of the mass of the Milky Way Galaxy, but they are relatively gas-rich and appear to be, at the present epoch, forming stars at a more prodiguous rate than our Galaxy (c/. Lequeux, 1984).