wp-plugin-hostgator domain was triggered too early. This is usually an indicator for some code in the plugin or theme running too early. Translations should be loaded at the init action or later. Please see Debugging in WordPress for more information. (This message was added in version 6.7.0.) in /home4/scienrds/scienceandnerds/wp-includes/functions.php on line 6114ol-scrapes domain was triggered too early. This is usually an indicator for some code in the plugin or theme running too early. Translations should be loaded at the init action or later. Please see Debugging in WordPress for more information. (This message was added in version 6.7.0.) in /home4/scienrds/scienceandnerds/wp-includes/functions.php on line 6114Source:https:\/\/www.quantamagazine.org\/new-clues-for-what-will-happen-when-the-sun-eats-the-earth-20231220\/#comments<\/a><\/br> Earth\u2019s fate rests on a coin flip.<\/p>\n In 5 billion years, our sun will balloon into a red giant star. Whether Earth survives is an \u201copen question,\u201d said Melinda Soares-Furtado<\/a>, an astrophysicist at the University of Wisconsin, Madison. Sure, Earth could be swallowed by the sun and destroyed. But in some scenarios, Earth escapes and is pushed further out into the solar system.<\/p>\n Now, a nearby planetary system has offered clues to our planet\u2019s cosmic hereafter. About 57 light-years away, four planets orbit a sunlike star that is 10 billion years old \u2014 twice as old as the sun, and already in the advanced stages of its life. Stephen Kane<\/a>, an astrophysicist specializing in planetary habitability at the University of California, Riverside, recently modeled what might happen<\/a> to the elderly system\u2019s planets when the star becomes a red giant in a billion years. He found that most of the inner planets will be engulfed, but that the outermost known planet, which has an orbit similar to Venus\u2019, might survive.<\/p>\n The star\u2019s advanced age makes it easier to model its expansion and offers a more accurate forecast of our own planetary system\u2019s future. \u201cIt\u2019s a very interesting paper,\u201d said Jonathon Zink<\/a>, an astrophysicist at the California Institute of Technology. \u201cIf we can find [more] systems at various phases of stellar evolution, we can probably piece together what\u2019s going [to happen].\u201d<\/p>\n When a planet is engulfed, death can be swift. In 2022, Ricardo Yarza<\/a>, a stellar astrophysicist at the University of California, Santa Cruz, simulated what happens<\/a> when a red giant swallows a planet. He found that if the planet starts out close enough to the star, its orbit rapidly decays. Gas in the star\u2019s atmosphere creates a drag on the planet, and \u201cthe planet keeps plunging deeper and deeper into the star,\u201d Yarza said. Within a few hundred years, most planets will be destroyed.<\/p>\n Until recently, these final moments of a doomed planet\u2019s life \u201chad never been observed directly,\u201d said Kishalay De<\/a>, an astronomer at the Massachusetts Institute of Technology. But in 2020, De\u2019s team saw a star 12,000 light-years away temporarily become a few hundred times brighter. The flash was too dim to have come from a merger with another star. But it was just the right intensity to have been produced by a planet-size meal, De and his colleagues reported<\/a> in May.<\/p>\n The team surmised that a planet a few times more massive than Jupiter had been caught up as the 10-billion-year-old star began expanding into a red giant. \u201cThis is the future of our solar system,\u201d De said.<\/p>\n When a main-sequence star like our sun \u2014 also called a G-type star or yellow dwarf \u2014 reaches the end of its life, it runs out of the hydrogen needed to power nuclear fusion in its core. As the star turns to other fuel sources and loses mass, its core gets hotter, and its atmosphere puffs up over millions of years. Eventually, our sun will grow more than 200 times as wide as its present size.<\/p>\n That swelling sun will consume Mercury and probably Venus, before growing so large it approaches Earth\u2019s orbit \u2014 a distance known as one astronomical unit, or AU. But it could expand even further. \u201cIn some models,\u201d said Antonino Lanza<\/a>, an astronomer at the Astrophysical Observatory of Catania in Italy, \u201cit can engulf Mars.\u201d The main uncertainty, he said, lies in how much mass the sun will lose as it ages; the more it sheds, the smaller its final radius will be. \u201cThat is poorly known,\u201d he said.<\/p>\n For now, our best estimates suggest that the sun will grow to somewhere between 0.85 and 1.5 AU. But as the star loses mass, the weaker pull of gravity will increase Earth\u2019s orbit, meaning our planet could escape engulfment.<\/p>\n To see Earth\u2019s future, astronomers turn to a crystal ball filled with alien planetary systems. Their goal is to find sunlike stars that will soon balloon (or have just ballooned) into red giants.<\/p>\n That\u2019s why Rho Coronae Borealis, a nearby yellow dwarf star that\u2019s thought to be reaching the end of its sunny life, caught Kane\u2019s attention. Three of its four known planets orbit close to the star, well within Venus\u2019 path around our sun. The outermost planet, with a year lasting 282 days, is similar in orbit to Venus.<\/p>\n Kane\u2019s analysis, published last month<\/a>, shows that the growing star will engulf the three inner planets. The innermost of those worlds, thought to be rocky and nearly four times the mass of Earth, will evaporate within a few hundred years. \u201cThe plasma superheats the planet and causes it to essentially break down,\u201d Kane said. \u201cEven the rocks on the surface will melt away.\u201d The next world out, a Jupiter-mass gas giant, is so large that it will spiral inward and be ripped apart by the star\u2019s gravity, rather than evaporating. The third planet, a smaller Neptune-mass world, will likely also be engulfed and evaporated.<\/p>\n But the outermost planet \u2014\u00a0also about the mass of Neptune \u2014\u00a0may survive. As the star expands, it will temporarily engulf the planet for several thousand years. During this time, extreme temperatures will roast the planet\u2019s surface, but the planet itself should survive because the star\u2019s atmosphere isn\u2019t very dense at this distance. The star will then contract and expand once more, again engulfing the planet for several millennia. If the planet can survive being toyed with like a tomcat\u2019s mouse, it could then emerge from the atmosphere as the star shrinks for a final time. \u201cSo it has an opportunity right at the end to escape,\u201d Kane said.<\/p>\n Kane, for one, is sanguine about the planet\u2019s chances and what they might mean for our own world. \u201cI suspect that Earth will move outward, and it will survive,\u201d he said.<\/p>\n If a planet can escape engulfment, its chances for a longer life are promising. When a star like our sun expands into a red giant and sheds its outer layers, eventually the only thing left is a dense, white-hot stellar corpse known as a white dwarf. These objects contain as much as half the mass of the original star, packed into an area the size of Earth. They should continue to burn for trillions of years.<\/p>\n In the past two decades, scientists have found a handful of exoplanets<\/a> orbiting white dwarfs, said Mary Anne Limbach<\/a>, an exoplanet scientist at the University of Michigan. These planets survived their star\u2019s red giant phase, although it\u2019s not clear exactly how. Some of the worlds \u2014\u00a0which tend to be larger gas giants \u2014 were probably too far from their star to be swallowed, while others may have been pushed outward as the star huffed and puffed. (Astronomers have also seen evidence that some planets were not so lucky<\/a> in the form of polluted white dwarfs<\/a>, which are rich in elements associated with planets, such as magnesium and iron.) Ongoing observations by the James Webb Space Telescope (JWST) are expected to turn up dozens more exoplanets orbiting white dwarfs.<\/p>\n As unusual as they might seem, these planetary systems could still be habitable, said Limbach, who leads some of the JWST white dwarf observations. \u201cThere is a place around a white dwarf where you can get liquid water\u201d on a planet\u2019s surface, she said. But \u201cit\u2019s a very challenging environment.\u201d<\/p>\n More observations of evolved solar systems, and more models like Kane\u2019s, could provide greater insight into the fate of our own. For now, the death of our planet is a roll of the dice away from certainty. Humans may be long gone from Earth\u2019s surface, but anyone glancing in our direction 5 billion years from now might see our planet ride out our sun\u2019s dying breaths \u2014 or, perhaps, disappear in a brief flash of light.<\/p>\n Quanta\u00a0is conducting a series of surveys to better serve our audience. Take our\u00a0<\/i>physics reader survey<\/i><\/a>\u00a0and you will be entered to win free\u00a0<\/i>Quanta\u00a0merchandise.<\/i><\/p>\n<\/div>\n <\/br><\/br><\/br><\/p>\n
\nNew Clues for What Will Happen When the Sun Eats the Earth<\/br>
\n2023-12-20 21:58:39<\/br><\/p>\nCrispy Worlds<\/strong><\/h2>\n
Our Evolving Star<\/strong><\/h2>\n
The Great Escape<\/strong><\/h2>\n