Scientists Figured Out How And When Our Sun Will Die, And It's Going to Be Epic
What will our Sun look like after it dies? Scientists have made predictions about what the end will look like for our Solar System, and when that will happen. And humans won't be around to see the final act.
Previously, astronomers thought it would turn into a planetary nebula – a luminous bubble of gas and dust – until evidence suggested it would have to be a fair bit more massive.
An international team of astronomers flipped it again in 2018 and found that a planetary nebula is indeed the most likely solar corpse.
The Sun is about 4.6 billion years old – gauged on the age of other objects in the Solar System that formed around the same time. Based on observations of other stars, astronomers predict it will reach the end of its life in about another 10 billion years.
There are other things that will happen along the way, of course. In about 5 billion years, the Sun is due to turn into a red giant. The core of the star will shrink, but its outer layers will expand out to the orbit of Mars, engulfing our planet in the process. If it's even still there.
One thing is certain: By that time, we won't be around. In fact, humanity only has about 1 billion years left unless we find a way off this rock. That's because the Sun is increasing in brightness by about 10 percent every billion years.
That doesn't sound like much, but that increase in brightness will end life on Earth. Our oceans will evaporate, and the surface will become too hot for water to form. We'll be about as kaput as you can get.
It's what comes after the red giant that has proven difficult to pin down. Several previous studies have found that, in order for a bright planetary nebula to form, the initial star needs to have been up to twice as massive as the Sun.
However, the 2018 study used computer modeling to determine that, like 90 percent of other stars, our Sun is most likely to shrink down from a red giant to become a white dwarf and then end as a planetary nebula.
"When a star dies it ejects a mass of gas and dust – known as its envelope – into space. The envelope can be as much as half the star's mass. This reveals the star's core, which by this point in the star's life is running out of fuel, eventually turning off and before finally dying," explained astrophysicist Albert Zijlstra from the University of Manchester in the UK, one of the authors of the paper.
"It is only then the hot core makes the ejected envelope shine brightly for around 10,000 years – a brief period in astronomy. This is what makes the planetary nebula visible. Some are so bright that they can be seen from extremely large distances measuring tens of millions of light years, where the star itself would have been much too faint to see."
The data model that the team created actually predicts the life cycle of different kinds of stars, to figure out the brightness of the planetary nebula associated with different star masses.
Planetary nebulae are relatively common throughout the observable Universe, with famous ones including the Helix Nebula, the Cat's Eye Nebula, the Ring Nebula, and the Bubble Nebula.
Cat's Eye Nebula (NASA/ESA)
They're named planetary nebulae not because they actually have anything to do with planets, but because, when the first ones were discovered by William Herschel in the late 18th century, they were similar in appearance to planets through the telescopes of the time.
Almost 30 years ago, astronomers noticed something peculiar: The brightest planetary nebulae in other galaxies all have about the same level of brightness. This means that, theoretically at least, by looking at the planetary nebulae in other galaxies, astronomers can calculate how far away they are.
The data showed that this was correct, but the models contradicted it, which has been vexing scientists ever since the discovery was made.
"Old, low mass stars should make much fainter planetary nebulae than young, more massive stars. This has become a source of conflict for the past 25 years," said Zijlstra
"The data said you could get bright planetary nebulae from low mass stars like the Sun, the models said that was not possible, anything less than about twice the mass of the Sun would give a planetary nebula too faint to see."
The 2018 models have solved this problem by showing that the Sun is about the lower limit of mass for a star that can produce a visible nebula.
Even a star with a mass less than 1.1 times that of the Sun won't produce a visible nebula. Bigger stars up to 3 times more massive than the Sun, on the other hand, will produce the brighter nebulae.
For all the other stars in between, the predicted brightness is very close to what has been observed.
"This is a nice result," Zijlstra said. "Not only do we now have a way to measure the presence of stars of ages a few billion years in distant galaxies, which is a range that is remarkably difficult to measure, we even have found out what the Sun will do when it dies!"
The research has been published in the journal Nature Astronomy.
An earlier version of this article was first published in May 2018.
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Scale of the Universe - Be Amazed!
Everyone knows the universe is huge, but most people don't understand how huge it really is. This article will try to show the amazingly massive scale of the universe to you. It surely is a very humbling experience!
EARTH - OUR HOME
EARTH COMPARED TO SMALLER PLANETS IN OUR SOLAR SYSTEM
EARTH COMPARED TO LARGER PLANETS IN OUR SOLAR SYSTEM
COMPARED TO OUR SUN
OUR SUN COMPARED TO OTHER STARS
MILKY WAY - OUR GALAXY
THE OBSERVABLE UNIVERSE
Sun will swallow Earth: Official
No escape from star's clutches
Posted in Space, 27th February 2008 10:09 GMT
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Two scientists from the University of Sussex and Mexico's University of Guanajuato appear to have confirmed that if we're still around in 7.6 billion years, global warming will be the least of our worries, since our beloved Mother Earth will be drawn inexorably towards the Sun and snuffed from existence.
Sussex Uni's Robert Smith and Guanajuato's Klaus-Peter Schroeder got out their calculators to determine once and for all whether Earth would escape a blazing death by spinning into a more distant orbit around the Sun, or whether it's ultimately curtains.
The former theory suggests that, as the Sun expands into a red giant, it will eject its outer gaseous layers, thereby losing mass and weakening its gravitational grip on the Blue Marble.
However, this get-out clause doesn't factor in tidal forces or the drag of the Sun's outer layer, according to the doomsday boffins. The Earth actually exerts its own (modest) gravitational pull on the Sun, causing the face closest to us to bulge out - an extrusion which constitutes bad long-term news.
Smith explained to Space.com: "Just as the Earth is pulling on the Sun's bulge, it's pulling on the Earth, and that causes the Earth to slow in its orbit. It will spiral back and finally end up inside the Sun."
In addition to this fatal attraction, the gaseous layers escaping from the Sun will exacerbate the problem, creating drag on Earth's orbit, further slowing it.
Smith said these crucial factors had hitherto been overlooked in determining Earth's fate. He explained: "Although people have looked at these problems before, we would claim this is the best attempt that's been made to date, and probably the most reliable. What we've done is to refine existing models and to put the best calculations we can at each point in the model."
Of course, while it's interesting to ponder our planet's distant fate, we'll actually be long gone before the fireworks. Smith predicted: "After a billion years or so you've got an Earth with no atmosphere, no water and a surface temperature of hundreds of degrees, way above the boiling point of water. The Earth will become dry basically. It will become completely impossible for life of any kind to exist. It's a pretty gloomy forecast."
The researchers' findings will be published in the journal Monthly Notices of the Royal Astronomical Society. ®
On the other hand...
Last September we reported on a "red giant survivor" V 391 Pegasi b, which was spied orbiting its bloated mother star "slightly beyond" the expansion zone within which planets are doomed.
Roberto Silvotti, researcher at the INAF-Osservatorio Astronomico di Capodimonte, said: "As far as our planets are concerned, we expect Mercury and Venus to disappear in the Sun's envelope, whereas Mars should survive.
"The fate of the Earth is less clear because its position is really at the limit. All this will happen in about five billion years, when the Earth will be more or less the same age as V 391 Pegasi b, i.e. 10 billion years."
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When galaxies collide: How the sky will look when Milky Way crashes into Andromeda system... in four billion years
- Collision between galaxies will happen in four billion years
- Stars will be tossed into different orbit around Milky Way's core - including our Sun
- Two billion years later, the two galaxies will 'merge' into one
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This incredible image shows how our skies will look when the Milky Way galaxy collides with our cosmic neighbour, the Andromeda galaxy, in four billion years.
Astronomers at NASA have confirmed that, according to their latest models, a major collision will occur in a major cosmic event.
The head-on encounter is expected to happen four billion years from now - catapulting our sun to another area of the galaxy, with stars tossed on to different orbits, astronomers at the Space Telescope Science Institute revealed on Thursday.
Starting off as a tiny speck in the distance, the galaxy known as Andromeda (left of the picture) looks harmless at first
Previously just a small dot, earthlings of the future would be forgiven for panicking as Andromeda moves closer to our galaxy
The formerly tiny galaxy now dominates the foreground of the computer generated image as it swallows up the Milky Way
The Aftermath: Following the collision of the two galaxies, a countless number of stars will be sent spinning into space as Andromeda and the Milky Way lose their previous forms
Although Earth and its solar system won't be destroyed, it will be pushed away from the galactic core more than it is now.
'After nearly a century of speculation about the future destiny of Andromeda and our Milky Way, we at last have a clear picture of how events will unfold over the coming billions of years,' said Sangmo Tony Sohn, Baltimore, Maryland-based institute.
After the Andromeda galaxy finally strikes the Milky Way, it will be another two billion years before the two totally come together and form a single elliptical galaxy.
Colossal: This NASA illustration shows the Milky Way (left) and the Andromeda galaxy, which are expected to collide in four billion years from now
Impact: Earth won't be destroyed when Andromeda smashes into the Milky Way (pictured), but stars will likely be tossed into different orbits and it will take an additional two billion years for the two galaxies to totally merge
A mutual pull of gravity is bringing the two galaxies together as Andromeda, known to scientists as M31, falls at a ferocious rate toward the Milky Way.
Andromeda is currently 2.5million light-years away.
'In the 'worst-case scenario' simulation, M31 slams into the Milky Way head-on and the stars are all scattered into orbits,' said team member Gurtina Besla in a statement.
The Andromeda is plowing toward Earth's galaxy at roughly 250,000 miles per hour.
That rate is the equivalent of traveling from Earth to the moon in an hour.
Astronomers also believe a third, smaller galaxy called the Triangulum will also be a part of the collision and could join the Milky Way and Andromeda mash-up.
Fast: Andromeda (pictured) is plowing toward Earth's galaxy at roughly 250,000 miles per hour, which is the equivalent of traveling from Earth to the moon in 60 minutes
It previously had been difficult to determine whether the two galaxies would slam into each other.
Members of the NASA Hubble Space Telescope team, however, were able to make certain that the two will crash with exact views of Andromeda's sideways motion.
Change: When the two galaxies collide, the sun (pictured) will be catapulted across another area of the galaxy
'This was accomplished by repeatedly observing select regions of the galaxy over a five- to seven-year period,' said the institute's Jay Anderson, in a statement.
The astronomers used extremely powerful cameras to capture the measurements that were crucial to understand the motion of Andromeda.
As the universe expands and accelerates, collisions can happen between two galaxies close together because of the gravity from dark matter around them.
These types of mergers were more likely to happen in the past when the universe was not as large as it is today.
