Rare Earth hypothesis the atmosphere is not stripped over time by solar winds. A terrestrial planet of the right size is needed to retain an atmosphere, like Earth and Venus. On Earth, once the giant impact of Theia thinned Earth's atmosphere, other events were needed to make the atmosphere capable of sustaining life. The Late Heavy Bombardment reseeded Earth with water lost after the impact of Theia. The development of an ozone layer formed protection from ultraviolet (UV) sunlight. Nitrogen and carbon dioxide are needed in a correct ratio for life to form. Lightning is needed for nitrogen fixation. The carbon dioxide gas
Gas-s-s-s military gas leak involving an experimental agent that kills everyone on Earth over the age of 25. (A cartoon title sequence shows a John Wayne-esque Army General announcing — and denouncing — the "accident"; the story picks up after the victims have died.) The lead characters, Coel and Cilla, are played by Robert Corff and Elaine Giftos, and the cast features Ben Vereen, Cindy Williams, Bud Cort and Talia Shire (credited as "Tally Coppola") in early roles. Country Joe McDonald makes an appearance, as spokesman "AM Radio". In Dallas, at the Southern Methodist University, news comes in about a gas