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Most planets can exist for a long time, but they can not last forever. Starving stars and violent planetary neighbors can completely destroy a world, while impacts and excessive volcanism can make a world habitable by depriving the planet of its waters. As far as we know, there are also many theoretical means that could spell the death knell for the planet.
"Planets die all the time in our galactic neighborhood," wrote Sean Raymond, a planetary modeler at the Astrophysics Laboratory in Bordeaux, France. series of blogs about the death of planets. Raymond has studied many ways for planets to reach their goal. Although not all planets die, most end up in the global morgue.
Climate Catastrophe
The Earth's climate cycle plays an important role in ensuring that the planet is neither too hot nor too cold to sustain life. But it does not take much for the climate in a rocky world such as the Earth to be shaken, triggering events leading to an incredibly hot planet or a snowballing world.
On Earth, the temperature is regulated by the amount of carbon dioxide in the atmosphere. Carbon dioxide and others greenhouse gas in the atmosphere (such as water, methane and nitrous oxide) act as a blanket, keeping the planet warm by slowing the amount of solar radiation returned to the space. When carbon dioxide accumulates in the atmosphere, it warms the surface of the planet, causing rain more. Precipitation then removes some of the carbon dioxide from the atmosphere and deposits it in the carbonate rocks of the sea floor, and the planet begins to cool.
If carbon dioxide accumulates in the atmosphere faster than it can be reabsorbed into the rocks, for example due to increased volcanic activity, it can trigger a cooling effect. uncontrolled greenhouse. The temperatures can exceed the boiling point of the water, which can be a problem to maintain life, because all life as we know it needs water. Rising temperatures can also allow the atmosphere to escape into space by removing the protective shield that deflects solar radiation from the planet and from other stars.
The design of an artist of a frozen planet. If a planet cools enough, it could become a snowball world.
(Image: © Shutterstock)
"Greenhouse heating is a fact of life for an atmosphere, and desirable to a certain extent," Raymond wrote. "But things can get out of hand."
Heat is not the only way the climate can become deadly. When a planet becomes cold enough, this body turns into a snowball world, a rocky object covered with ice. The ice and snow are shiny and largely reflect the heat of a star in space, which has the effect of further cooling the world. On a world of surface volcanoes, blowouts can release carbon dioxide and other gases into the atmosphere, warming the world. But if the conditions of the snowball occur on a planet devoid of plate tectonics – and therefore volcanoes – the world may be permanently stuck in a snowball state.
According to Raymond, all planets potentially carrying lives run the risk of climate catastrophe, which can make a planet uninhabitable but not completely destroy it.
Wash or life
The tug of the neighboring worlds can fire on the orbit of a planet, which puts pressure on its interior and increases the heat of the Earth's middle layer, the mantle. This heat must find a way to escape, and the most typical method is to use a volcano.
Volcanic activity can significantly affect the environment of a planet. According to University Corporation for Atmospheric ResearchThe particles of gas and dust projected into the atmosphere by a volcano can affect the atmosphere of the planet, cool the planet and protect it from incoming radiation. In 1815, the eruption of Mount Tambora, the largest eruption in the history of the Earth, has produced so much ash that it has lowered global temperatures, making 1816 the so-called "summer-free year".
Volcanoes can also have the opposite effect – global warming – by releasing greenhouse gases into the atmosphere. Frequent and severe volcanic eruptions could trigger a greenhouse effect that would transform a habitable world like Earth into something more like Venus.
We do not have to look very far to find a real example of the world of volcanoes. The moon of Jupiter Io is the most volcanically active body in the solar system, with hundreds of volcanoes erupting continuously. If the Earth was as much fired as Io by the gravitational force of Jupiter, it would have 10 times more volcanic activity than Io, according to Raymond.
Calamity comet
Rock asteroids and icy comets are planetary "crumbs" that can cause significant problems to nearby worlds, especially when thrown by ice giants and gases.
When planets settle into their final orbits, their gravitational tugs can move asteroids and comets. Some may be pushed to the periphery of the planetary system, while others are rushed inward, eventually colliding with rocky worlds, where life may be trying to evolve.
In our outer solar system, the last movements of Neptune when it has settled into its permanent orbit have pushed multiple comets inward, passing them from planet to planet to Jupiter. . Jupiter threw some of these icy bodies outward, but others were rushed to Earth for a period known as Late heavy bombardment.
The concept of early Earth artist shows a surface struck by significant impacts.
(Image: © Simone Marchi / NASA)
Today, Earth accumulates about 100 tons (90 tons) of interplanetary material every day in the form of dust. Objects greater than 100 meters (330 feet) do not fall to the surface of the surface until every 10,000 years, while corpses more than a third of a mile (1 kilometer) do not collapse. than every 100,000 years, according to NASA. Center for Studies on Near-Earth Objects.
When giant planets throw these destructive crumbs into the sun, collisions increase and impacts occur more often. Medium sized objects can throw dust and debris into the atmosphere, which can interfere with atmospheric processes. Giant impacts can have even more serious effects, not only because of the devastation that occurred at zero, but also because they may generate enough debris to cause significant damage. winter impact, throwing the planet into a mini ice age. With enough consecutive impacts, the effects of climate could reinforce each other until the world becomes uninhabitable.
Based on observations of planetary remains found around other stars, Raymond calculated that about 1 billion Earth-like planets in the galaxy would eventually be destroyed by an asteroid bombing.
A bad big brother
As the most massive object of the solar system after the sun, Jupiter acts as a big brother protector, protecting the debris from small rocky planets and giants around other worlds probably play the same role. But if a gas giant like Jupiter becomes unstable, it could have a devastating effect on the smaller worlds that surround it.
After the formation of the stars, the disc of remains of material gives rise to planets. The gravitational tugs of gas and dust in the disc exert a force on the planets and can keep the gas giants online for the first million years. Once it's gone, however, the planets can change their orbits more easily. Since giant planets are much smaller than their rocky siblings, their gravitational thrusts can have a significant impact on the movement of smaller planet orbits. But the big worlds are not immune; Two giant planets can shoot at each other and even pass very close to each other. According to Raymond, these giants rarely collide, rather offering gravitational kicks to each other. Finally, some worlds could be forced out from orbit completely and become logged to float in space not attached to any star.
Raymond has calculated that about 5 billion rocky worlds have been destroyed by gas giants. Most of the destruction probably took place shortly after the formation of the planets. However, a handful of them probably occurred later in the life of the system, after it had time to evolve. If only 1% of gaseous giants became unstable later in their planetary life, it is possible that 50 million planetary systems destroyed inhabited worlds by throwing them into their star.
One way to destroy planets is to collide with each other, but this probably does not happen very often.
(Image: © Vadim Sadovski / Shutterstock)
Stellar snacking
Like the planets, the stars can finish and their transformation can have dramatic effects on the planets that orbit them.
Red dwarf starsfor example, it may take more than 100 million years for their brightness in the long term, ten times longer than our sun. The planets orbiting a red dwarf can remain in the habitable zone for a few million years, but as the star gets brighter, any water vital to life can be seen. evaporate at higher temperatures.
But planets orbiting a hot red dwarf could still support life. "We do not know if this process is completely draining the planets or just ripping off a few outer layers of the ocean," Raymond wrote. "If a planet has enough water trapped in its interior (it is thought that the Earth sometimes has its surface water in the mantle), it could then endure losing its oceans by releasing later new ones." result is unknown – for the moment. " Estimated Raymond that 100 billion planets may have been dried by their red dwarf.
Sunlike stars give habitable planets more time to hang in the water and give life a chance. But the temperature of the sun is also changing, it is slowly clearing over billions of years. According to Raymond, in a billion years, the planet will no longer be in the habitable zone; the water will no longer remain liquid on the surface of the Earth. Instead, the planet will experience a rapid greenhouse effect and eventually look like Venus.
When a star like a sun reaches the age of 10 billion years, it will miss hydrogen and will grow between 100 and 200 times more than its current size. (Our sun is 4.5 billion years old, so we have some time before that happens.) In the solar system, Venus and Mercury will be: swallowed by the star, while the changing gravity of the sun will push Mars and the outer planets further. The Earth is on the edge and can suffer one or the other destiny. About 4 billion rocky worlds are probably consumed by a star that brightens slowly.
The most massive stars explode in burning supernova after a relatively short life of a few million years. No planet has been found around these massive stars, but it is perhaps because there are so few massive stars to look for and as the exoplanets are still difficult to find, Raymond wrote. Whatever the case may be, all the planets surrounding these giant stars will probably be destroyed by the explosive death of the star.
This article is inspired by the series of astronomer Sean Raymond on How do planets die.
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