By all counts, Earth is on a one way trip to oblivion. Our aging Sun will see to that. Within 500 to 900 million years from now, photosynthesis and plant life on Earth will reach a death-spiral tipping point as the Sun continues its normal expansion and increases in luminosity over time. <\/p>\n
Trouble is, researchers are still unsure about all the grisly endgame details, and their models of such slow motion horrors are hard to test. But a team of researchers now say that finding and observing nearby aging Earth-analogues, undergoing the ravages of their own expanding sun-like stars, will help Earth scientists understand how the stellar evolution of our own sun will affect life here on Earth. [Within] 500 million light years figure most plants become extinct, although some could potentially last up to 900 million years from now by employing more carbon-efficient photosynthetic pathways, Jack OMalley-James, an astrobiologist at the University of St. Andrews in the U.K. told Forbes. At this point <\/p>\n
Night sky over Death Valley. Photo Credit: Wikipedia <\/p>\n
In a paper to appear in the journal Astrobiology, OMalley-James, the lead author and colleagues, notes that as the Suns luminosity pushes the inner edge of our solar systems current habitable zone at 0.99 AU (or one Earth-Sun distance) just too far out. <\/p>\n
Even so, finding a planet that is a near analogue to the far-future Earth (an old-Earth-analogue) could provide a means to test these predictions; including declines in species diversity, extent of habitat and ocean loss, and changes in such planets geochemical cycles. <\/p>\n
If we did find such a planet, detailed long-term studies could give us an insight into its long-term carbon cycle, possible showing us whether carbon dioxide (CO2) levels really will plummet over the next billion years in the way we expect, said OMalley-James. <\/p>\n
As he explains, in Earths own far-future, plant life will be extinct and the biosphere as we know it will have collapsed into an unfamiliar form. Thus, even if astronomers spots such a dying Earth, around an older sun-like star, could they recognize any remaining signs of life there? <\/p>\n
When it comes to positively identifying life on a distant planet, it is still very early days, said OMalley-James. It would be very difficult to pin down any remotely observable signature that we could be 100 percent certain is caused by life on a distant planet. However, this doesnt make work such as this futile. <\/p>\n
The hope is that if astronomers can determine the stars age with high enough accuracy, coupled with the fact that the planet has been in a circumstellar habitable zone for billions of years, but is now encroaching upon the very inner-edge of the habitable zone, then OMalley-James says future observations of such planets could make the case that they had observed the dying gasp of the planets biosphere. <\/p>\n
The team ran simulations that placed hypothetical Earths around six aging G spectral type stars all within some 30 light years from Earth. OMalley-James notes that in each case, his team used hypothetical examples of an aging Earth-like planet, all in the inner-hot edge of their respective habitable zones. <\/p>\n
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Lessons From Dying Extrasolar Earths<\/a><\/p>\n","protected":false},"excerpt":{"rendered":" By all counts, Earth is on a one way trip to oblivion. Our aging Sun will see to that. Continue reading