Observational studies of protoplanetary disks with ALMA are reviewed. Outstanding mapping capability of ALMA has allowed us to reveal internal structure of protoplanetary disks in unprecedented detail. Its remarkable achievements include detection of small-scale structure directly linked to the planet formation and discovery of significant dust concentration in a disk. Asymmetry in a disk and a hint of the formation of gaseous planets within a timescale of 10⁶ years were not seriously considered in a classical theory for the solar system formation, but these can be regarded as the clues to the general theory for the formation of planetary systems in the universe.

Akatsuki has started observations in an orbit around Venus. The first attempt to enter a Venus orbit was a failure, but the second attempt after 5 years of cruise was a success. The goal of the mission is to understand the Venusian meteorology. The high-speed atmospheric circulation “super-rotation” and the formation of sulfuric acid clouds are studied with multi-wavelength imaging observations.

More than 200 years have passed since the first discovery of an asteroid, Ceres, in 1801, and at present the number of discovered asteroids has exceeded 700,000. Spacecraft have approached about 10 asteroids, and we know various features of asteroids, which were not seen from ground based observations. Japanese spacecraft Hayabusa succeeded in sample return form an asteroid, and the sample analysis is on going. Thus, our knowledge about asteroids is increasing rapidly now. In this paper we summarize about the current situation from the point of asteroid explorations.

Last 20 years have witnessed the rapid progress in extrasolar planetary science. This article reviews the diversity and general property of exoplanets, revealed by previous dedicated exoplanet surveys, by the Doppler and transit techniques in particular, from both space and ground. The diversity and the property of detected exoplanets lead to a revision in the classical planet formation and evolution scenarios and induced their further progresses. Here, I summarize the observational techniques to test the classical and new planet formation and evolution theories. I also introduce world-wide campaigns on the exoplanet search in the next decade.

The search for alien life may lead to the answer for the essential question about “the origin of life in the universe”. Although we have no evidence of extraterrestrial life for now, recent explorations have found several candidate bodies as extra-terrestrial habitat in terms of chemical compounds and energetics. Here we summarize current understandings for the candidates, Mars, Jovian moon Europa, and Saturnian moon Enceladus and Titan, as a potential habitat.

The distribution of asteroids in solar system is not uniform due to the perturbation of the gravity of Jupiter. There are Kirkwood's gaps in the distribution at some resonance points, while there are also peaks in the distribution at other resonance points. We investigate the distribution of asteroids in terms of the eigenvalue problem of the Liouvillian defined by the Poisson bracket with the Hamiltonian instead of solving trajectory dynamics. In the three-body problem of an asteroid, Sun and Jupiter, unperturbed eigenstates of the Liouvillian for the two-body problem are degenerate due to the resonance. We demonstrate that the perturbation of Jupiter on the distribution of asteroids at resonance is described by the degenerate perturbation theory that is a technique developed in quantum mechanics. At the Kirkwood's gap, the perturbation of Jupiter removes the degeneracy and results in the level repulsion in the eigenvalues of the Liouvillian. For 3 : 2 resonance, Hilda triangle in the asteroid distribution is successfully reproduced by the spatial pattern of the steady state with zero eigenvalue of the Liouvillian. These results show that the Liouvillian dynamics based on the concept of the classical states is useful in analyzing classical systems at resonance.