We review what we have learnt about flares and prominences using multi-wavelength observations in the perspective of testing theoretical models.

Solar coronal heating is a complex problem due to the variety of scales and physical phenomena involved, and intricacy of “boundary conditions”. Lattice models and self-organized criticality provide means to model phenomenologically some of the physics involved over a wide range of scales, and reproduce certain statistical features of solar flares. Furthermore, these models offer a basis for the study of Parker's hypothesis of coronal heating by nanoflares. We provide a short review of this approach pioneered by Lu & Hamilton (1991) and related more recent works involving lattice models.

The paper reports about several actual problems of the solar wind and solar energetic particle studies. Primary focus is on unsolved questions. The clear and sharp boundary in the phase space between solar wind plasma particle populations and “solar energetic particles” does not exist. Because of this separate consideration of “solar energetic particles” has only limited applicability and needs some reservations, which should be clearly stated and not forgotten to avoid possible errors and misinterpretations, which sometimes happen in the literature. In any case, the solar wind particles often serve as a big reservoir for acceleration (or cooling) of less abundant energetic particles. Solar wind and solar energetic particles are just two selected populations (big and small) in their joint distribution functions. It is very difficult and even impossible in many instances to have demarcation between particle populations in the energy space or indicate their ultimate “origins” in the coordinate space. It is because of the absence of localized “accelerators”, “heaters” or “sources” of particles. All these three categories mentioned above often have very limited physical meaning, but sometimes they can be useful and localized in the momentum and coordinate space. We are still too far from complete knowledge and understanding of many relevant questions in this regard.

A brief overview of upcoming total solar eclipses in 2008–2010 is presented. Global maps illustrate the geographic region of visibility for each eclipse. In addition, preliminary weather prospects are discussed.

Everybody understands what is meant by an eclipse: a body that covers another one. However, the general audience and the students in particular do not know exactly “What the relative positions of the Earth, the Sun and the Moon have to be in order for an eclipse to take place?”

You can read a newspaper or watch TV and observe that the information about an eclipse is not correct. In my country, it was stated, in a very important newspaper, that “the solar eclipse will take place tomorrow because there will be a Full Moon”.

Teaching this topic in schools or in educational sessions in observatories, it is a good idea to introduce a simple model that maintains the proportion between the diameters and distances of these three bodies. This contribution will introduce this model, showing their applications in the playgrounds of the school, for sunny days or in the classroom for cloudy days.

Historical records of the Nile water level provide a unique opportunity to investigate the possibility that solar variability influences the Earth's climate. Particularly important are the annual records of the water level, which are uninterrupted for the years 622–1470 A.D. These records are non-stationary, so that standard spectral analyses cannot adequately characterize them. Here the Empirical Mode Decomposition technique, which is designed to deal with non-stationary, nonlinear time series, becomes useful. It allows the identification of two characteristic time scales in the water level data that can be linked to solar variability: the 88 year period and a time scale of about 200 years. These time scales are also present in the concurrent aurora data. Auroras are driven by coronal mass ejections and the rate of auroras is an excellent proxy for solar variabiliy. Analysis of auroral data contemporaneous with the Nile data shows peaks at 88 years and about 200 years. This suggests a physical link between solar variability and the low-frequency variations of the Nile water level. The link involves the influence of solar variability on the North Annual Mode of atmospheric variability and its North Atlantic and Indian Oceans patterns that affect rainfall over Eastren Equatorial Africa where the Nile originates.

Baily beads timings of annular eclipse of October 3, 2005 and total eclipse of March 29, 2006 have been analyzed for measuring a variation of the actual solar radius between those dates. After 1/3 of all beads events analyzed, corrections to average solar radius are known within $\pm$0.19”. High resolution video have been made at the boundaries of totality-annularity paths, to increase the number of beads visible. Comparison of observations made with different combinations of telescopes/filters/detectors is discussed.

A pinhole camera has the advantage of undistorted field of view. Its imaging capability is limited by random (diffraction and atmospheric seeing) and systematic (penumbra) effects. The Pinhole Solar Monitor, PSM, measures the solar angular diameter by timing meridian transits. Meridian transits have been videorecorded with UTC synchronization at the pinhole gnomon of Santa Maria degli Angeli church in Rome. The tarature of this Clementine Gnomon is outlined with its accuracy as PSM. On the Moon an array of such PSM equipped with 1000 lines for parallel transits can monitor 0.1” variations of solar diameter.

One of the observational facts about sunspots is that magnetic field strength of sunspots varies in narrow interval $\approx$ from 1 to 4–5 kG. Why sunspot equilibrium is stable only under these values? To answer this question, we propose the energetic model of sunspot, which involves the gravitational energy of the system. Formation of a sunspot is followed by redistribution of gas density along the vertical: cooled plasma flows down, inside the “magnetic funnel”, from above the sunspot to the “low boundary of magnetic flux tube”, i.e. to the region where the magnetic field of sunspot decreases abruptly with depth. Theoretical model gives the interval of stable sunspot equilibria exactly between 0.8–1.0 and 4–6 kG, which suites the observations. The “depth of sunspot” turns to be about 2–4 Mm – this fact now is approved by helioseismology. Also, the long-term (T$\,{>}\,$20 min) eigen oscillations of sunspot, as a whole, are studied. These oscillations were measured by different methods, being observed as quasi periodical vertical displacements of the body of sunspot followed by variations of its radius and magnetic field strength.