ИСТИНА

The nature of UV-radiation in galaxies of different morphological types will be reviewed. The UV-excess in massive elliptical galaxies which have predominantly old stellar populations is traditionally explained by the contribution of low-mass stars at very late, poorly known stages of evolution - by so called `AGB-manque' stars or by the populations of extended horizonthal branch. However recent results from the GALEX survey for a rich sample of nearby ellipticals have also demonstrated probable traces of recent star formation in a third of all ellipticals observed. In spiral galaxies the extended UV-disks have been discovered by the GALEX; they are certainly illuminated by the current star formation, but what has provoked star formation in the area of very low gas density, beyond the distribution of older stars, is a puzzle yet. A separate very interesting problem which can be solved only in the UV spectral range, is a search for `missing baryons' - for the warm gas which can be detected through the absorption lines of highly ionized O and C in the spectra of background sources (quasars). Some results are already reported, but even more remains to be done relating this topic.