... In space, therefore, we should choose technologies carefully. ... For instance, the solar-photon sail--pushed through space by linear-momentum transfer from reflected solar photons--could carry water mined on comets or hydrated asteroids towards human habitats in dry solar systems. ... Article Highlights New Type Of Astronomy ,,Clubs: Online Amateur astronomers "are beginning to look very different from what they did only a few years ago," an article in last months Sky & Telescope observed. ...

... 000, 1­13 (2010) Printed 21 September 2011 A (MN L TEX style file v2.2) A universal ultraviolet-optical colour­colour­magnitude relation of galaxies I1gor V. Chilingarian1,2, and Ivan Yu. ... Received 2011 Sep 15; in original form 2011 Feb 6 ABSTRACT The bimodal galaxy distribution in the optical colour­magnitude diagram (CMD) comprises a narrow "red sequence" populated mostly by early-type galaxies and a broad "blue cloud" dominated by star-forming systems. ...