According to Beatles singer-songwriter George Harrison, all things must pass, and according to decades of mathematical and astronomical models, these include the sun.
So when is Sun expected to burn out?
Although the final death of our average-sized solar mass is trillions of years in the future, the “life” of the sun in its current phase, known as the “main sequence” – where nuclear fusion of hydrogen allow it to radiate energy and provide enough pressure to keep the star empty collapses under its own mass – will end about 5 billion years from now.
“The sun is less than 5 billion years old,” said Paola Testa, an astrophysicist at the Center for Astrophysics, a collaboration between the Smithsonian Astrophysical Observatory and the Harvard University Observatory. “It’s a kind of middle-aged star, in the sense that its lifespan would be around 10 billion years or so.”
After the sun burns off most of the hydrogen in its core, it will move on to the next stage as a red giant. At this point about 5 billion years in the future, the sun will stop generating heat through nuclear fusion, and its core will become unstable and shrink, according to NASA. Meanwhile, the outer part of the sun, which will still contain hydrogen, will expand, glows red as it cools. This expansion will gradually swallow the neighboring planets of the sun, Mercury, and Venus, and carry the solar winds so much that they destroy them. Earth magnetic field and separates from its atmosphere.
Of course, this will almost certainly bad news for any life still on our planet at the time – assuming any life has survived a 10% increase in sun’s luminosity, which is expected to evaporate Earth’s oceans in 1 billion to 1.5 billion years, according to a 2014 study published in Geophysical research letter. According to a 2008 study published in the journal Monthly Notice of the Royal Astronomical Society.
Then the sun will begin to combine helium left over from hydrogen fusion to carbon and oxygen, before finally collapsing to its core, leaving beautiful planetary nebula – a glowing shell of hot, leftover plasma – in its outer layers as it shrinks into an extremely dense, significantly hotter, Earth-sized corpse known as a white dwarf. Testa says the nebula will only be visible for about 10,000 years – just the blink of an eye in cosmic time. From there, what’s left of the sun will take trillions of years to cool before eventually becoming a non-emitting object.
To achieve this timeline for both the sun and all stars of its relative mass, scientists need to know how it emits energy, which is difficult before fusion is taken into account. nuclei in the solar masses.
“A lot of science is relatively new, as it was in the last century, because an integral part of understanding how a star works comes from understanding nuclear reactions and Fusion“Testa, who studies the heating mechanisms and processes of X ray emissions, such as solar flares, in the outer layers of the solar atmosphere. “Before the 1930s, one of the main ideas about how stars work was that energy only came from gravitational energy.”
Once astronomers and astrophysicists better understand fusion, they can come up with more complete models, along with observed emission data from some stars, of life. of the stars.
“By synthesizing various information from many different stars, astronomers and astrophysicists can build a model of how stars evolve,” Testa told Live Science. “This gives us a pretty accurate guess about the age of the sun.”
This age – about 4.6 billion to 4.7 billion years old – is also attested by radiocarbon dating of oldest known meteorite, formed from the same solar nebula, a swirling disk of gas and dust that forms the sun and planetary bodies in the solar system.
Thanks to these tools, scientists have a good understanding of when sunlight will eventually turn off and disappear.
Originally published on Live Science.
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