The motions of two typical meteor streams of the Jupiter family, the α Virginids and the α Capricornids, were considered over the interval 1902–2003, perturbations by Venus to Neptune being taken into account. The substantial transformations of their orbits in Jupiter's sphere of action and its neighbourhood were studied. Conclusions are made concerning the role of large perturbations by Jupiter in dispersing meteor streams and altering the visibility conditions of meteor showers.

Observational data on radiants of meteor showers and the structure of meteor streams may be used as an indirect source of information about the evolution of cometary and meteor orbits. Investigation of the structure of some meteor streams provides evidence for comparatively high velocities of ejection of meteoroids from cometary nuclei. Further evolution of the streams is determined by planetary perturbations and other factors, the influence of which depends on the size and composition of the meteoroids.

From radar observations carried out during 1967–1968 a catalogue of 20 000 orbits was obtained. A method has been developed for identifying meteor streams and associations, and the orbits of the meteors recorded during January-April 1968 have been analysed. Among them 163 streams have been identified, and these contain 33.5% of the total number of orbits. Comparison with the orbits of the short-period comets of q < 1.1 AU shows considerable differences.

In order to understand the origin and evolution of the solar system it is especially important to study the small bodies – asteroids, comets and meteoroids – because in the planetesimal state (preceding the present state) the matter was dispersed.

The temporary focusing effect of planetary perturbations on the particles of a meteor stream is studied. It is indicated that allowance for collisions could result in more permanent focusing, leading to the possible formation of a comet.

From radar observations carried out during 1967–1968 a catalogue of 20000 orbits was obtained. A method has been developed for identifying meteor streams and associations, and the orbits of the meteors recorded during January–April 1968 have been analysed. Among them 163 streams have been identified, and these contain 33.5% of the total number of orbits. Comparison with the orbits of the short-period comets of q <1.1 AU shows considerable differences.

An attempt is made to use Monte-Carlo techniques to model the process of formation of meteor streams. It is supposed that meteor streams are formed as the result of ejection of meteoroids from a cometary nucleus at perihelion. Possible ejection velocities are determined for the Draconids, Perseids, Leonids, and Taurids. In general the values do not exceed 100 m s-1. The data obtained can also be used to estimate the ages of the streams.

A simplified form of the Jacobi integral in the three-body system Sun-Jupiter-comet or asteroid provides an excellent method for discriminating between cometary and asteroidal orbits. Omitting the librating bodies, unambiguous separation is obtained for all known objects with reliable orbital data, i.e., about 600 comets and 1800 asteroids. The only exception is the peculiar asteroid 944 Hidalgo – which is presumably a comet. The intermediate region is occupied exclusively by bodies revolving in resonance with Jupiter, and the value of the libration argument yields a sharp secondary criterion in these cases. Besides the direct perturbational capture of long-period comets from high-eccentricity orbits into Jupiter's family, a ring of nearly circular orbits between Jupiter and Saturn is suggested as another significant source of short-period comets. For these comets the subsequent operation of nongravitational effects gives a better chance of injection into small orbits of the Apollo type and for the formation of short-period meteor streams. Some phenomena (the outbursts of P/Schwassmann-Wachmann 1, the probable recent splitting of one parent body into P/Whipple and P/Shajn-Schaldach) give reasons for speculation about the population of this region, too distant for the discovery of typical asteroids or comets, by interplanetary particles up to sizeable solid bodies.

For the minor planets, comets, and meteors whose orbital elements are known values of the dispersions σi(a) of the inclination i for intervals of the semimajor axis a have been calculated. Calculations on the minor planets show that, from the point of view of secular perturbations, σi(a) is more stable than ī(a), and we have therefore taken it as a fundamental relation for further considerations. It has been found that the relations σi(a) are linear for minor planets, comets, and meteors with a > 2 AU. The lines are parallel, and for a > 2 AU the σi(a) are proportional to a. Meteors have a second straight line for a < 2 AU, and in this case σi(a) is proportional to 1/a. It is concluded that minor planets, comets, and meteors could have a common origin.