For more than three billion years now, Earth’s ability to support life has been a delicate balancing act. Climatic periods of severe cold or hot have brought life to its knees. Glaciers covered the planet in the “snowball Earth” epoch, which ended some 650 million years ago. During the extremeheat of the early Triassic period around 250 million years ago, tropical sea temperatures exceeded 100 degrees Fahrenheit.
But the temperature pendulum has always swung back from these extremes, thanks in large part to the moderating phenomenon of plate tectonics. The sliding movements of Earth’s crust regulate the amount of heat-trapping carbon in our atmosphere by trapping the carbon in the seafloor and releasing it later by way of volcanoes. In this way, the “carbon cycle” has helped stir our planet out of frozen slumbers and has curbed the greenhouse effect.
Yet all good things, as the saying goes, must come to an end. The driver of Earth’s tectonics is heat from our planet’s slowly cooling core and the decay of radioactive elements deep within the planet. In another few billion years, that heat will have largely dissipated and Earth’s geophysical activity will cease. Although life might have already bitten the dust by then, likely thanks to a warming Sun, the end of the moderating carbon cycle will exacerbate conditions for any embattled organisms that might still exist.
A new study considers life’s geophysical collapse on planets outside our solar system. Specifically, the paper looks at exoplanets orbiting red dwarf stars, which are smaller, cooler and less massive than our Sun. These dim red stars host the easiest planets for our telescopes to observe in the “habitable zone,” the orbital band in which surface water neither permanently freezes away nor boils off. Conveniently, a large portion of red dwarfs (and their attendant solar systems) are also older than our Sun. Older stars are less stormy than younger ones, further easing the detection of planets around them.
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For more than three billion years now, Earth’s ability to support life has been a delicate balancing act. Climatic periods of severe cold or hot have brought life to its knees. Glaciers covered the planet in the “snowball Earth” epoch, which ended some 650 million years ago. During the extremeheat of the early Triassic period around 250 million years ago, tropical sea temperatures exceeded 100 degrees Fahrenheit.
But the temperature pendulum has always swung back from these extremes, thanks in large part to the moderating phenomenon of plate tectonics. The sliding movements of Earth’s crust regulate the amount of heat-trapping carbon in our atmosphere by trapping the carbon in the seafloor and releasing it later by way of volcanoes. In this way, the “carbon cycle” has helped stir our planet out of frozen slumbers and has curbed the greenhouse effect.
Yet all good things, as the saying goes, must come to an end. The driver of Earth’s tectonics is heat from our planet’s slowly cooling core and the decay of radioactive elements deep within the planet. In another few billion years, that heat will have largely dissipated and Earth’s geophysical activity will cease. Although life might have already bitten the dust by then, likely thanks to a warming Sun, the end of the moderating carbon cycle will exacerbate conditions for any embattled organisms that might still exist.
A new study considers life’s geophysical collapse on planets outside our solar system. Specifically, the paper looks at exoplanets orbiting red dwarf stars, which are smaller, cooler and less massive than our Sun. These dim red stars host the easiest planets for our telescopes to observe in the “habitable zone,” the orbital band in which surface water neither permanently freezes away nor boils off. Conveniently, a large portion of red dwarfs (and their attendant solar systems) are also older than our Sun. Older stars are less stormy than younger ones, further easing the detection of planets around them.