But this is again unlikely. It's too small a target: the distance from the Earth to the Sun is around 50, times smaller than the distance to the edge of the Oort cloud. Researchers can hypothesise almost no end of threats to life on Earth. February was evidently apocalypse month: another study suggested that we should even worry about the mysterious "dark matter" in our galaxy. We really shouldn't, says Mamajek, given how little we actually know about dark matter. In fact, the take-home message from all of this research is that there isn't a plausible catastrophic agent from outside the solar system that could wipe out life on Earth within the next few billion years.
But there is one agent of destruction that certainly is powerful enough to wipe out swathes of species. Life's biggest threat could come from within, according to Peter Ward at the University of Washington in Seattle. He calls the idea the Medea hypothesis. The name is a nod to the famous Gaia hypothesis, named for the Greek goddess of the Earth, which suggests that life helps keep Earth habitable.
Medea, in stark contrast, is a Greek mythological figure famous for killing her own children. Ward argues that many of the mass extinctions in Earth's history were caused by life. For instance, about 2. There had never before been free oxygen, so the microbes living on Earth could not cope with it, and a massive extinction followed.
Then there were the first land plants, about million years ago. Plant roots broke up bedrock into soil, speeding up the chemical reaction between minerals in those rocks and carbon dioxide in the atmosphere.
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This stripped carbon dioxide from the atmosphere and weakened the greenhouse effect, triggering a lethal ice age. Fast-forward into Earth's distant future, and these kinds of effects could sterilise the planet, says Ward. The sun is getting hotter as it ages, and as a consequence the Earth will warm up. That means the chemical reaction between rocks and atmospheric carbon dioxide will speed up — a process that's accelerated even more by the action of plant roots. Eventually, so much carbon dioxide will have been removed from the air that plants can no longer perform photosynthesis.
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All plants will die, and animal life won't be far behind. This could happen surprisingly soon, says Ward, perhaps in just million years. There would still be microbes, but they'd be vulnerable. Just as in Agatha Christie's Murder on the Orient Express — spoilers for a novel published in — it would probably take several killers, acting at roughly the same time, to destroy all life on Earth, says Ward.
50 Interesting Facts About Earth
No one single event is going to do it. If none of that gets us, the Sun will. Our home star bathes us in light, and supplies the energy for almost all the life on Earth. But it won't be friendly forever. As we saw earlier, the Sun is gradually getting hotter. Eventually it will be hot enough to evaporate all Earth's oceans, and cause a runaway greenhouse effect that sends temperatures soaring upwards. This process might begin in about a billion years , and would wipe out all but the most resistant microorganisms.
But that's not all.
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Beginning around 5 billion years from now, the Sun will expand, becoming a swollen star called a red giant. So the expanding Sun will engulf, and destroy, the Earth. It's been suggested that Earth might escape. The Sun will lose mass as it grows, so Earth will spiral further out. But according to calculations performed in , this won't be enough to save our planet. If that's true, the only hope lies with us. If any humans are still around, they might have the technology to move the Earth to safety. Otherwise, life on Earth has a maximum life expectancy of 7. Earth Menu. Share on Facebook.
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http://autodiscover.manualcoursemarket.com Please note we can only post these within the UK. It is also a vital element of the Earth's climate system, helping to regulate global temperatures.
Measuring in at m and weighing 10, tonnes, the ship will push the boundaries of polar science and exploration. Until now it has been impossible to test the various theories put forward by scientists, but now climate scientists have been able to do just that thanks to NERC research ships. Microplastics -- particles of plastic smaller than five millimeters -- are The study Imagery like LiDAR can help researchers see through the tree cover, but subtle landforms can New Evidence of the Sahara's Age Sep.
New research looking into what appears to be dust that the Sahara blew over to the Canary Islands is providing the Yet despite the seeming permanence of cliffs, caves, fossils, and Why Are Mountains So High? It Doesn't Add Up Sep. Summaries Headlines. The new study may help guide the development and performance of solar photovoltaic
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