![]() ![]() ![]() Shields uses computer models to simulate the effects of host stars on their planets’ likely habitability. Modeling by several researchers, including Aomawa Shields of the University of California, Irvine, shows that small, rocky worlds orbiting red-dwarf stars – like the seven roughly Earth-sized planets orbiting TRAPPIST-1 – could, under some conditions, have stable climates and reduced susceptibility to deep-freeze. The extraordinary portraits these modelers paint are teaching us about previously unimagined possibilities – not only for potentially habitable worlds, but for the dynamic atmospheres of enormous, hot, gaseous planets, oddballs known as mini-Neptunes, or rocky, terrestrial planets locked in a deep freeze. “We’re using our understanding from Earth to inform our search for life, for habitability, on other planets,” said Nancy Kiang, an astrobiologist at NASA’s Goddard Institute for Space Studies in New York. They are tasking our increasingly sophisticated computer models, originally designed to model Earth’s climate, with simulating exotic (if idealized) worlds instead. So researchers are trying instead to narrow the focus and flesh out the potential habitability of the planets themselves. Such concepts are intriguing, and might one day contribute to the search for habitable worlds, but we don’t have enough data so far to make them useful for studies of exoplanets – planets around other stars. For bigger, hotter stars, it’s farther out for small, cool stars it is much closer in. The habitable zone – the distance form a star where liquid water could exist on the surface of a planet – varies by star type. Might the galaxy also have its own habitable zone – the distance from the galactic center with enough metal to seed rocky planets, yet free of killer supernovae or smothering molecular clouds? Open the lens a bit and pull back to take in a view of our entire, pinwheeling Milky Way galaxy. Jupiter’s Europa or Saturn’s Enceladus might also harbor some form of ocean-dwelling life – though well outside the traditional habitable zone around our Sun.ĭo gas giants preside over their own habitable zones, in our solar system or around other stars? If so, it would be governed by tidal forces instead of radiant temperature – the push and pull of a moon’s innards by the gas giant’s gravity, causing tidal heating to keep subsurface oceans in a liquid state. Or cast the net much farther out, beyond our system’s “ice line.” Our biggest gas giants are both orbited by frozen moons concealing oceans beneath the surface. It’s something in the habitable zone that isn’t.” “Is it habitable? It can’t retain an atmosphere. “The Moon is in the habitable zone in our solar system,” Voytek said. Broiling, barbecued Venus with its sulfuric acid clouds is much too hot for life as we know it freezing, desiccated Mars and its wisp of a carbon dioxide atmosphere is unpromising as well. ![]() In our system, Venus by some measures grazes the inner edge of our Sun’s habitable zone, and Mars falls just inside the outer boundary. “There are many other factors that contribute to establishing habitable conditions.”Įven well-known worlds close to home, in our own solar system, hint at far more variety than the chalk outline of the standard “habitable zone” suggests. “It’s very important to realize, it’s not just the location,” said Mary Voytek, the senior scientist for astrobiology at NASA headquarters in Washington, D.C. Are we alone in the universe? Revisiting the Drake equation
0 Comments
Leave a Reply. |