Operational methodologies are available to retrieve several parameters related to the land, air and oceans from satellite data which is capable of providing well calibrated data/observations over large areas giving a synoptic view on a repetitive and reliable basis. The capability of satellites to provide data in various spectral, spatial and temporal scales is of great advantage in studying the dynamic aspects of earth atmosphere system. The present day capabilities of satellites include spatial resolutions ranging from 10 m and above and repetition of a few hours (geosynchronous Satellite) to few days. Higher spatial resolutions and all weather capabilities (through microwave sensing) are becoming available in the immediate future. Towards utilising the potentials of space based systems, India has been operating INSAT series of satellite for weather monitoring and 1RS series of satellites for natural resources monitoring/management. The INSAT is a series of geostationary satellites stationed over Indian region to provide meteorological observations on a continuous basis in visible and thermal regions in addition to providing services for disaster warning related to Cyclones and remote location data collection platforms. The space based observations on meteorology over the past 5 years is proving to be a valuable data base for studies related to monsoon dynamics and tropical cyclones.

Numerical, self-consistent, n-body integrations of the solar system show significant indications of medium-term (i.e. several million-year) stability for the various planet-Sun L4,L5 configurations. A progress report of our computations, emphasizing the inner solar system, will be given. There exist interesting possibilities for these locations (including the Earth) as the sites for longer term scientific applications, both pure and applied.

Present and future measurement of the Large Magellanic Cloud (LMC) particularly in the radio and high energy gamma ray range offer the possibility of understanding the density and distribution of the cosmic rays in a galaxy other than our own and the role that they play in galactic dynamic balance. After a study of the consistency of the measurements and interpretation of the synchrotron radiation from our own galaxy, the cosmic ray distribution for the LMC is calculated under the assumption that the cosmic ray nucleon to electron ratio is the same and the relation to the magnetic fields are the same, although the implications of alternatives are discussed. It is seen that the cosmic ray density level appears to be similar to that in our own galaxy, but varying in position in a manner generally consistent with the concept of correlation with the matter on a broad scale.

Unlike the usual situation with theoretical physics which is testable in the laboratory, in cosmological theories of the universe one faces the following problems: The observer is part of the system, the universe, and this system cannot be altered to test physical theory. Even though one can in principle consider any part of the observable universe as separate from the acts of observation, the very hypothesis of big bang implies that in the distant past, space-time regions containing current observers were part of the same system. One, therefore, faces a situation where the observer has to be considered as inherently a part of the entire system. The existence of horizons of knowledge in any cosmological view of the universe is then tantamount to inherent observational limits imposed by acts of observation and theory itself. For example, in the big bang cosmology the universe becomes opaque to radiation early on, and the images of extended distant galaxies merge for redshifts, z, of the order of a few. Moreover, in order to measure the distance of a remote galaxy to test any cosmological theory, one has to disperse its light to form a spectrum which would cause confusion with other background galaxies. Since the early universe should be described in quantum terms, it follows that the same problems regarding quantum reality and the role of the observer apply to the universe as a whole. One of the most fundamental properties of quantum theory, non-locality, may then apply equally well to the universe. Some of the problems facing big bang cosmology, like the horizon and flatness problems, may not then be preconditions on theoretical models but may instead be the manifestations of the quantum nature of the universe.

Radiative cooling strongly affects the thermal structure of dense jet, such as in SS433, through free-free emission. From the dynamical aspect, the beam width of a cooled jet does not expand, unlike from an adiabatic jet. From the thermal aspect, cooling efficiency determines the ratio of X-ray region of high temperature to optical one of low temperature. However, this ratio is influenced by the heating due to contained high-energy particles, which produce synchrotron radiation in the tail of the jet.

Extragalactic jets can also be considered in a similar way due to other energy loss mechanisms.

According to the principles of light deflection, different occulting times of an occultation respond to different basic theories of physics. An occulting way for testing of light deflection in earth orbit or beyond may be possible and is proposed. An application is studied and some suggestions are presented.

Three general models have been constructed for the fantastically powerful “central engine” that powers the enormous energy output from quasars and active galactic nuclei (AGN). One model assumes a rapidly rotating accretion disk around a central black hole (however the disks, thick or thin, are subject to violent instabilities). Another assumes that in some postulated circuitry energy is extracted from the rotational portion of the deepest potential hole known, a black hole. Both models appear implausible.

The third model is the STRONG MAGNETIC FIELD MODEL (SMF) in which an extremely strong gravitationally bound current loop (GBCL) is formed during the gravitational collapse that forms the galaxy or quasar, producing a very intense dipole magnetic field anchored in the nucleus. SMF, first published in 1962, thus predicted the vertical magnetic field configuration seen today at our own galactic nucleus; to some the radio arcs observed suggest a dipole magnetic field there, just as SMF predicts.