![]() ![]() ![]() While there is a general consensus about the formation of terrestrial planets, two very different mechanisms have been proposed for the formation of the gas and ice giant planets. The final phase of terrestrial planet formation involves giant impacts between the protoplanets and planetary embryos and requires on the order of 100 million years. Km-size planetesimals are large enough to grow by gravitationally deflecting bodies that might otherwise not collide with them, leading to a period of runaway growth to lunar-sized planetary embryos. Terrestrial planets form by the slow process of collisions and sticking between increasingly larger dust grains, pebbles, boulders, and mountains of rock and ice termed planetesimals. The disk that formed the Solar System is called the solar nebula. ![]() Dense interstellar clouds of gas and dust collapse under their self-gravity to form central protostars orbited by rotationally supported, flattened disks in which planets later form. Planetary systems form out of the leftovers of the star formation process. The lecture will present some recent results: the base-pairing properties of a series of acyclic backbone derived oligomeric systems tagged with alternative heterocycles as recognition elements. The Department of Chemistry at The Scripps Research Institute 10550 North Torrey Pines Road, MB16, La Jolla, CA-92037, USAĮxtensive base-pairing studies of oligonucleotides consisting of canonical bases tagged to a variety of cyclic sugar-phosphate backbones-conducted in the context of work toward an etiology of the structure type of the natural nucleic acids-have led to a broadening of the scope of investigations to include informational oligomer systems that are not confined to typical sugar-backbones and canonical bases. Search for Potentially Primordial Genetic Systems ![]()
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