It's getting ugly.
- the aging sun
- the red giant
- Can life survive the end of the sun?
- First record of a planet surviving the death of a star
- additional resources
Ourfrom the sunDeath is still a long way off, about 4.5 billion years or so, but it will happen one day, and then what will happen to ourssolar system?
The problem begins before death itself: the first thing we have to deal with is the old sun itself. As thehydrogen fusioncontinues inside the sun, the result of this reaction, helium, accumulates in the core.
the aging sun
With all the debris flying around, it's getting harder for the sun to perform its fusion dance. But the crushing weight of the Sun's atmosphere doesn't change, so to maintain equilibrium, the Sun must increase the temperature of its fusion reactions, ironically resulting in a hotter core.
That is, the older the sun gets, the brighter it gets. The dinosaurs knew of a darker sun than the one we see today and in just a few hundred million yearsTierrait gets too hot to handle.
Our atmosphere is being stripped. Our oceans will evaporate. We look like this for a whileVenus, trapped in a suffocating carbon dioxide atmosphere.
And then it gets worse.
Related:25 Weird And Wild Facts About The Solar System
the red giant
In the final stages of hydrogen fusion, our sun will bulge and bulge, distort and bulge and turn red. The red giant sun will consumeMercuryand Venus for sure. It may or may not spare the Earth, depending on exactly how big it is. When the sun's bloated atmosphere reaches our world, the earth will disintegrate in less than a day.
But even if the Sun's expansion stops abruptly, it won't be pretty for Earth. The extreme energies emitted by the sun will be strong enough to vaporize rock, leaving nothing but the dense iron core of our planet.
The outer planets won't enjoy as much radiant power from the sun either. ringsSaturnThey're made of almost pure water ice, and the future sun will just be too hot to survive. The same is true of the ice-covered worlds orbiting these giants.Europa,Enceladus, and everyone else loses their icy shell.
First, the increased radiation will blow up the four outer planets and remove their atmosphere, which is as fragile as that of a terrestrial planet. But as the sun continues to grow, some of the outer tendrils of its atmosphere can reach the giants and travel through funnelsheaviness. The outer planets can feed on this material and grow much larger than ever before.
But the sun isn't going down yet. In its final stages, it will swell and contract again and again, pulsating for millions of years. This is not the most stable situation gravitationally. The disrupted Sun will push and pull the outer planets in strange directions, potentially pulling them into a death hug or driving them out of the system altogether.
Can life survive the end of the sun?
For a few hundred million years, the outermost parts of oursolar systemit will be a worthy place to call home. With so much heat and radiation emanating from the red giant sun, theZone habitable- the region around a star where temperatures are just right for liquid water - will drift outward.
As we have already seen, the moons of the Outer Worlds will first melt, shedding their icy envelopes and possibly harboring oceans of liquid water on their surfaces. Finally theKuiper Belt Objects, includingPlutoand his mysterious friends will also lose their ice cream. The larger ones can transform into mini-Earths orbiting a distant, distorted red sun.
But eventually our Sun will give up the fight, shedding its outer atmosphere in a series of outbursts that will leave behind the star's core: a red-hot blob of carbon and oxygen.
It iswhite dwarfIt will initially be incredibly hot and emit X-rays that can wreak havoc on life as we know it. But in about a billion years, the white dwarf will settle down to more manageable temperatures and just hang out for trillions and trillions of years.
This faint white dwarf will host a new habitable zone, but because the previous Sun will be so cold, that zone would be incredibly close, much closer than Mercury is orbiting our Sun today.
At that distance, any planet (or planetary core) would be susceptible to tidal disturbances, a nice way of saying that the white dwarf's gravity could inadvertently tear a planet apart.
But that might be the best we'll get.
First record of a planet surviving the death of a star
In October 2021, astronomers discovered the first planet orbiting a white dwarf. Hediscovery, according to the scientists, gives a glimpse into the possible future of the solar system.
The newly discovered planet is aRiesengas40% greater thanJupiter, orbits a dead star some 6,500 light-years from Earth toward the center of our galaxy, theMilky Way.
Scientists don't know much about the planet, not even its distance from the star. The planet was accidentally discovered in 2010 during a "gravitational microlensing effect."
Gravitational microlensing occurs when two stars are at different distances from each otherTierratemporarily align from our perspective. The foreground star's gravity acts like a lens, amplifying the background star's light. When a planet orbits the foreground star, the magnified light is briefly distorted as the planet whizzes past the star.
“To see an object through gravitational microlensing, you only have to rely on the mass of the object; you don't need light emanating from it," says Jean-Philippe Beaulieu, a professor of astrophysics at the University of Tasmania in Australia and director of the Institute for Astrophysics of Paris, told Space.com. "We could see that an object about half the mass of the Sun was in orbit with a planet the mass of Jupiter."
Only during later observations with one of the WM Keck telescopes in Hawaii did astronomers realize that the star in the background was so faint that it had to be a white dwarf.
Learn more by listening to the episode"Can planets survive the death of their star?"on the Ask A Spaceman Podcast, available atitunes(opens in a new tab)and on the internet athttp://www.askaspaceman.com.
Blackman, J.W. et al. A Jupiter analogue orbiting a white dwarf star, Nature, October 13, 2021
NASA, NASA missions spy on first possible 'surviving' planet to embrace white dwarf star on September 16, 2020
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Paul M. Sutter is an astrophysicist at SUNY Stony Brook and the Flatiron Institute in New York City. Paul received his PhD in Physics from the University of Illinois at Urbana-Champaign in 2011 and spent three years at the Institute of Astrophysics in Paris, followed by a research fellowship in Trieste, Italy. His research focuses on many different topics, from the emptiest regions of the Universe to the first moments of the Big Bang and the search for the first stars. As an "Agent to the Stars", Paul has been passionately involved with the public in popular science for several years. He is the host of the popular show "Ask a Spaceman!" Podcast, author of "Your Place in the Universe" and "How to Die in Space" and appears frequently on television, including The Weather Channel, for which he is the official space specialist.