N. (1999). Science, 283:1135–1138. PR-171 price Bernstein, M. P., Dworkin, J. P., Sandford, S. A., and Allamandola, L. J. (2001). Ultraviolet irradiation of naphthalene in H2O ice: Implications for meteorites and biogenesis. Meteor. Plan. Sci., 36:351–358. Bernstein, M. P., Dworkin, J. P., Sandford, S. A., Cooper, G. W., and Allamandola, L. J. (2002). Racemic amino acids from the ultraviolet photolysis of interstellar ice analogues. Nature, 416:401–403. Cronin, J. R., and Pizzarello, S. (1997). Enantiomeric

excesses in meteoritic amino acids. Science, 275:951–955. Engel, M. H., and Macko, S. A. (1997). Isotopic evidence for extraterrestrial non-racemic amino acids in the Murchison meteorite. Nature, 389:265–268. Kuan, Y.-J., Charnley, S. B., Huang, H.-C., Tseng, W.-L., and Kisiel,

Z. (2003). Interstellar glycine. Astrophys. J., 593:848–867. Martins, Z., Botta, O., Sephton, M. A., and Ehrenfreund, P. (2004). Purines and pyrimidines in carbonaceous chondrites: A re-analysis. Meteor. Plan. Sci., 39, Suppl. Proceedings of the 67th Annual Meeting of the Meteoritical Society, August 2–6, 2004, Rio de Janeiro, Brazil, Abstract No. 5145. Muñoz Caro, G. M., Meierhenrich, U. J., Schutte, W. A., Barbier, B., Arcones Segovia, A., Rosenbauer, H., Thiemann, W. H.-P., Brack, A., and Greenberg, J. M. (2002). Amino acids from ultraviolet irradiation of interstellar ice analogues. Nature, 416:403–406. Nuevo, M., Auger, G., Blanot, D., and d’Hendecourt, L. (2008). A detailed study of the amino acids produced from the vacuum UV irradiation of interstellar

SB431542 cost ice analogs. Orig. Life Evol. Biosph., 38:37–56. Snyder, L. E., Lovas, Cediranib (AZD2171) F. J., Hollis, J. M., Friedel, D. N., Jewell, P. R., Remijan, A., Ilyushin, V. V., Alekseev, E. A., and Dyubko, S. F. (2005). A rigorous attempt to verify interstellar glycine. Astrophys. J., 619:914–930. Stoks, P. G., and Schwartz, A. W. (1979). Uracil in Carbonaceous Meteorites. Nature, 282:709–710. E-mail: mnuevo@arc.​nasa.​gov Hypothesis of Formation of Planets from Nebula: Why Are the Planets Different in Their Chemical Compositions? Ostrovskii V.E.1, Kadyshevich E.A.2 1Karpov Inst. Phys. Chem., Moscow, Russia; 2Obukhov Inst. Atmosph. Phys., Moscow, Russia Most of the planetists believe that the Solar System originated from a nebula (a giant plasma cloud) (Shmidt, 1949; Hoyle, 1981), which arouse as a result of the supernova explosion about 4.6 billion years ago. More than 99% of nebular atoms were H and He. Several models (e.g., Jang-Condell and Boss, 2007; Boss, 2008; Alibert, et al., 2005) were proposed for simulating the processes of planet formation. However, neither the history, nor the physics and chemistry of planet formation are known in detail. There is an opinion that the radius of a planet is the key parameter controlling most of its evolutional features (Albarède and Blichert-Toft, 2007). Meanwhile, a planet radius may be time-dependent and the character of this dependence can not be now specified reliably.