From 2001, when I began my PhD study at the Astronomical Institute of the Slovak Academy of Sciences, I have studied comets and meteors, as well. Nowadays, I am still working in this very interesting field of astronomical research.

Within my PhD study, I investigated the origin of comets. Since the origin of comets is closely related to the origin and evolution of cometary reservoir, the well-known Oort Cloud, I concentrated my research to this still questionable topic. I dealt with a new alternative scenario of the Oort Cloud origin, developed by my PhD supervisor, Dr. Lubos Neslusan. In his work (Neslusan, 2000, A&A, vol. 361, p. 369-378), he assumed that the comets are generally created before the collapse of protosolar nebula, in giant molecular clouds, and proved that, after the collapse, the comets had to remain at large distances from the centre of the system. On the basis of this scenario and real observations of comets, I estimated population of comets in the Oort Cloud, and also the mass of this reservoir. I used a direct numerical integration of cometary orbits for 4.5 Gyrs, and at the end, compared the results of my numerical integration with real observations, taken from the "Catalogue of Cometary Orbits". The comparison led to the estimations of the population and mass of the Oort Cloud, using an alternative scenario of its origin.

In 2005, I and Dr. Neslusan (2005, A&A, vol.437, p. 1093-1108) studied the outer Oort cloud on the basis of observations of new comets. The comets enter the planetary region from the outer, dynamically active part of the Oort Cloud. We studied this part by a numerical integration of a large amount of the orbits of hypothetical comets representing this cometary reservoir. We determined the distribution of the semi-major axis, and estimated this population and total mass, as well as some other characteristics. In this work we estimated, that the lower limit of the outer Oort Cloud population is 1x1011 to 2x1011.

Nowadays, I and my colleagues are trying to model and explain the origin of the Oort Cloud with respect to stellar perturbations of this reservoir. In our research, we take into account perturbations by the dominant Galactic tide and nearly passed stars, as well. First, we developed a model of the stellar passages around the solar system, which has to reflect both the frequency and perihelion distribution of the passing stars, in the same time. In our work, we have taken characteristics of real stars provided by HIPPARCOS. After the creation of the model, we recently started to study the evolution of orbits of the planetesimals in the protoplanetary disk under the gravitational perturbation by 4 giants planets and influence of Galactic tide, together with stellar perturbations based on our model. On the basis of this evolution, we expect to be able to say more about the origin of the Oort Cloud. We use RMVS3 integrator from SWIFT packages (Levison), and RADAU integrator from MERCURY6 package (Chambers). Since we have to perform a very large amount of numerical integrations, we decided to use clusters of PCs joined in "Enabling Grids for E-Science II" project, with hundreds of processors available for our task.

As I mentioned at the beginning, I am also interested in the study of meteor streams. Together with my colleagues, we recently worked on dynamical evolution of the Perseid meteor stream. In more details, we revealed a fine structure of this meteor stream (using the method of indices) and then on the basis of numerical integrations of orbits we showed that found structures can be interpreted as the products of gravitational perturbations of giant planets (mainly of Jupiter and Saturn) on particles of the stream.

In general, my work is focused on dynamics of the small-body populations in the solar System.