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Earth-sized planets are just right for life

发布时间:2019-03-14 01:19:02来源:未知点击:

By David Shiga THE discovery of extrasolar super-Earths – rocky planets about five to ten times the mass of Earth – has raised hopes that some may harbour life. Perhaps it’s a vain hope though, since it now seems that Earth is just the right size to sustain life. Life is comfortable on Earth in part because of its relatively stable climate and its magnetic field, which deflects cosmic radiation capable of damaging organic molecules as well as producing amazing auroras (see right). The long-term stability of Earth’s climate depends on the way the planet’s crust is broken up into plates,