The outer worlds planets7/4/2023 ![]() ![]() “We don’t know what is needed to start life,” says Don Brownlee, an astronomer with the University of Washington in Seattle and co-author of the book, “The Life and Death of Planet Earth.” Brownlee says that if warm wet interiors and organic materials are all that’s needed, then Pluto, Triton, and the Kuiper Belt Objects could harbor life. Even if a planet has all the elements that favor habitability, life will not necessarily appear. Such characteristics include a planet’s internal activity, the reflectivity, or “albedo” of a planet, and the thickness and composition of the atmosphere. ![]() The influence of the sun is not the whole story, however – the characteristics of a planetary body go a long way toward determining habitability. Because temperature on Pluto will not be very different then, than Miami Beach’s temperature now, I like to call these worlds ‘warm Plutos,’ in analogy to the plethora of hot Jupiters found orbiting sun-like stars in recent years.” “Our solar system will then harbor not one world with surface oceans, as it does now, but hundreds, for all of the icy moons of the giant planets, and the icy dwarf planets of the Kuiper Belt will also bear oceans then. “When the sun is a red giant, the ice worlds of our solar system will melt and become ocean oases for tens to several hundreds of millions of years,” says Stern. These bodies are rich in organic chemicals, and the heat of the red giant sun will melt their icy surfaces into oceans. Stern thinks Neptune’s moon Triton, Pluto and its moon Charon, and the Kuiper Belt Objects will have the best chances for life. Life as we know it is not likely to appear on gaseous planets. Astronomers have discovered gaseous planets orbiting very close to their parent star in other solar systems, and these “hot Jupiters” seem to hold onto their gaseous atmospheres despite their proximity to the intense radiation. The prospects for habitability on the gaseous planets Saturn, Neptune and Uranus may not be affected all that much by the red giant transition. But not all these worlds will have an equal chance at life. Saturn, Uranus, Neptune and Pluto all lie within 10 to 50 AU, as do their icy moons and the Kuiper Belt Objects. The habitable zone will shift gradually through the 10 to 50 AU region as the sun grows brighter and brighter, evolving through its red giant phase. The habitable zone of a solar system is the region where water can remain in a liquid state. He says that planets located 10 to 50 AU will be in the red giant sun’s habitable zone. Alan Stern, Director of the Southwest Research Institute’s Department of Space Studies in Boulder, Colorado. Yet the conditions that make life possible could appear elsewhere in the solar system, according to a paper published in the journal Astrobiology by S. But whether the Earth is consumed or merely singed, all life on Earth will have passed into oblivion. While the sun’s atmosphere is predicted to reach Earth’s orbit of 1 AU, red giants tend to lose a lot of mass, and this wave of expelled gases could push Earth just out of range. ![]()
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