The Program Group for World-wide Development of Astronomy (PG-WWDA) is one of nine Commission 46 program groups engaged with various aspects of astronomical education or development of astronomy education and research in the developing world. In the case of PG-WWDA, its goals are to promote astronomy education and research in the developing world through a variety of activities, including visiting astronomers in developing countries and interacting with them by way of giving encouragement and support.

A total of 701 comets received names between July 2005 and June 2008. Comets observed only from the SOHO and STEREO missions, as well as further comets recognized from the long-defunct SOLWIND satellite, accounted for 520 of these names.

The Program Group for the World-wide Development of Astronomy (PG-WWDA) is one of nine Commission 46 program groups engaged with various aspects of astronomical education or development of astronomy education and research in the developing world. In the case of PG-WWDA, its goals are to promote astronomy education and research in the developing world through a variety of activities, including visiting astronomers in developing countries and interacting with them by way of giving encouragement and support.

The Program Group for the World-wide Development of Astronomy (PGWWDA) is one of nine Comm. 46 program groups engaged with various aspects of astronomical education or development of astronomy education and research in the developing world. In the case of PGWWDA, its goals are to promote astronomy education and research in the developing world through a variety of activities, including visiting astronomers in developing countries and interacting with them by way of giving encouragement and support.

In this paper it is explained how asteroids with large aphelion distances avoid very close approach to Jupiter. Namely, since for asteroids with resonant mean motions the critical arguments librate as it has been known for many years, and for those with non-resonant mean motions the eccentricities change with the argument of perihelion so the distance to Jupiter cannot be very small.

Also some behaviours of Kuiper-belt asteroids are studied by a similar way and it is found that the libration region for the argument of perihelion appears only when the eccentricity is very large. Therefore, even though the eccentricity is very large it is possible for any Kuiper-belt asteroid to avoid very close approach to any of the planets.

This paper describes how the families of minor planets were discovered and how minor planets are classified into families and shows several evidences that at least some families were originated by collisions of minor planets. In fact for major families there are much more fainter minor planets than in other regions and when the families were discovered by Hirayama in 1918 only one sixth of the total numbered minor planets belonged to families whereas now more than one third of them belong to the families. It is also emphasized that the classification into the families is theory dependent and that any theory available now is not accurate enough to derive stable quantities for the families to study their origins as the families are usually bounded partly by mean motion and/or secular motion commensurability regions in the phase space.

The numbered asteroids are classified into families by a new method proposed by the author(Kozai, 1979a) and their characteristics are studied by several aspects. It seems to the author that there are two kinds of the families, one being very compact in the phase space and containing many faint as well as a few bright asteroids and one being rather loose and bounded by secular and mean motion commensurable regions.

In order to compute satellite motions with centimeter accuracy, the reference system, to which they are referred, should be carefully chosen. In fact there are many kinds of the reference systems. In this paper advantages and disadvantages of various reference systems are discussed.

In 1962 the author published a paper on secular perturbations of asteroids with high eccentricity and inclination (Kozai, 1962) and found that for such asteroids the secular perturbations are more complicated than those estimated by the classical linear theory. Before that the author(Kozai, 1954) tried to extend the classical theory to include terms of squares of disturbing masses, eccentricities and inclinations in expressions of secular motions of angular variables and found that the sum of the longitudes of the perihelion and the ascending node is not as stable quantity as the classical theory predicted, and, therefore, it cannot be used to estimate the ages of asteroid families. Then Williams(1969) and Yuasa(1973) extended the classical theory further.

Solar perturbations in Saturnian satellite motions are computed with accuracy of 10-5 to try to analyze observed data of orbital elements for Titan. Perturbations due to Iapetus in Titan’s orbit are also developed by taking into account the motion of the orbital plane of Iapetus. Then the mass of Iapetus is determined by the motion of the orbital plane of Titan. Also oblateness parameters of Saturn and the mass of Rhea are determined by seven secular motions for six satellites. It is also found in the analysis that G. Struve’s values for the semi-major axes adopted in almanacs differ from the computed values by using the new data.