How and when the solar system will die

Previously, two moons revolved around the Earth, which then merged together. Titan, the satellite of Saturn, is an ideal analogue of our planet, it may well have life. And asteroids, which are located between Jupiter and Pluto, for some reason are called "centaurs". You can learn about these and other facts about space from the book “When the Earth had two Moons. Cannibal planets, ice giants, mud comets and other luminaries of the night sky”, which was recently published by the publishing house“Alpina non-fiction”.

The creator of a fascinating excursion into the history of the solar system is Eric Asfog, American planetary scientist and astronomer. The author not only works at the Laboratory for the Study of Planets and the Moon in Tucson, but also actively participates in NASA expeditions. For example, the Galileo mission, which studied Jupiter and its moons. Lifehacker publishes an excerpt from the first chapter of the scientist's work.

Like an internal combustion engine that sometimes flares back when cold started, the young Sun experienced irregular bursts of high activity for the first few million years. Stars passing through this developmental stage are called T Tauri stars after a well-studied active star in the corresponding constellation. Having passed the stage of birth pangs, the stars eventually obey the rule that the heaviest and brightest of them become blue, huge and very hot, while the smallest ones become red, cool and dull.

If you plot all the known stars on a graph, where there are blue stars on the left, red stars on the right, dim ones at the bottom, and bright ones at the top, they will mostly line up along a line going from the upper left corner to the lower right corner. This line is called the main sequence, and the yellow Sun is right in the middle of it. Also, the main sequence has many exceptions, as well as offshoots, where young stars that have not yet developed to the main sequence, and old stars that have already left it, reside.

The sun, a very ordinary star, emits its heat and light with almost constant intensity for 4.5 billion years. It is not as small as red dwarfs, which burn extremely economically. But not so big as to burn out in 10 million years, as happens with blue giants that go supernovae.

Our Sun is a good star, and we still have enough fuel in our tank.

Its luminosity is gradually increasing, having risen by about a quarter since its inception, which slightly shifted it along the main sequence, but you will not present any other claims to it. Of course, from time to time we encounter coronal mass ejections, when the Sun spews out a magnetoelectric bubble and bathes our planet with streams of radiation. Ironically, today, our artificial network is most vulnerable to the effect of a coronal mass ejection, because an electromagnetic pulse associated with this event can disrupt the operation of large sections of the power grid for a period from several weeks to two years. In 1859, the largest coronal ejection in modern history caused sparks in telegraph offices and magnificent aurora borealis. In 2013, the London insurance company Lloyd's estimated that the damage from such a coronal emission in the modern United States would be from 0.6 to 2.6 trillion dollars. … But compared to what happens in other planetary systems, this activity is completely harmless.

But this will not always be the case. In about 5-7 billion years, the "twilight of the gods" will begin for us, the last turmoil, during which the planets will leave their orbits. After leaving the main sequence, the Sun will become a red giant and in a few million years will engulf Mercury, Venus, and possibly Earth. Then it will contract, throwing half of its mass into space. Astronomers from neighboring stars will be able to observe in their skies a "new", expanding shell of sparkling gas that will disappear in a few thousand years.

The sun will no longer hold the outer Oort cloud, whose bodies will go to wander through interstellar space as cosmic ghosts. What is left of the star will contract until it becomes a white dwarf, an extremely dense body that shines with white light from its gravitational energy - barely alive but bright, the size of the Earth, but a billion times heavier. We believe that this is the fate of our solar system, in part because the Sun is an ordinary star, and we see many examples of such stars at various stages of evolution, and in part because our theoretical understanding of such processes has leaped forward and is in good agreement with the results of observations.

After the expansion of the red giant ends and the Sun becomes a white dwarf, planets, asteroids and other remnants of the inner solar system will begin to fall on it in a spiral - first due to deceleration in the gas, and then due to the action of tidal forces - until the superdense remnants the stars will not blow the planets to shreds one by one. In the end, there will be a disk of earth-like materials, mainly consisting of the torn off mantles of Earth and Venus, which will spiral down onto the destroyed star.

This is not just a fantasy: astronomers see this picture in the spectroscopic indicators of several neighboring "polluted white dwarfs", where the rock-forming elements - magnesium, iron, silicon, oxygen - are present in the star's atmosphere in quantities corresponding to the composition of minerals from the silicate class, such as olivine. This is the last reminder of the earthlike planets of the past.

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Planets that form around stars that are much larger than the Sun will have a less interesting fate. Massive stars burn at temperatures of hundreds of millions of degrees, consuming hydrogen, helium, carbon, nitrogen, oxygen and silicon in violent fusion. The products of these reactions become increasingly heavy elements until the star reaches a critical state and explodes like a supernova, scattering its insides around several light-years in diameter and at the same time forming almost all heavy elements. The question of the future of the planetary system, which could have formed around it, turns into a rhetorical one.

Now all eyes are fixed on Betelgeuse, a bright star that forms the left shoulder of the constellation Orion. It is separated from the Earth 600 light years, that is, it is not too far away, but, fortunately, not among our closest neighbors. Betelgeuse's mass is eight times that of the Sun, and according to evolutionary models, it is about 10 million years old.

Within a couple of weeks, the explosion of this star will be comparable in brightness to the glow of the moon, and then it will begin to fade; if this did not impress you, then keep in mind that from a distance of 1 astronomical unit, it is like watching a hydrogen bomb explode in a nearby courtyard. Over the course of geological time, supernovae have exploded much closer to Earth, irradiating our planet and sometimes leading to mass extinctions on it, but none of the stars closest to us is going to explode now.

The "hit zone" for this type of supernova is from 25 to 50 light years, so Betelgeuse poses no threat to us.

Since it is relatively close and has a gigantic size, this star is the first that we were able to see in detail through a telescope. Although the quality of the images is poor, they show that Betelgeuse is a strangely irregular spheroid, resembling a partially deflated balloon, which makes one revolution on its axis in 30 years. We see a huge plume or deformation by Pierre Kervella et al., “The Close Circumstellar Environment of Betelgeuse V. Rotation Velocity and Molecular Envelope Properties from ALMA,” Astronomy & Astrophysics 609 (2018), possibly caused by global thermal imbalance. It seems that she is really ready to explode at any moment. But, in truth, in order for any of us to have a chance to see the light of this event, Betelgeuse must have been blown to shreds in the days of Kepler and Shakespeare.

When a massive star explodes, the doors of its chemical kitchen are blown off their hinges. Ashes from a thermonuclear hearth scatter in all directions, so that helium, carbon, nitrogen, oxygen, silicon, magnesium, iron, nickel and other fusion products spread at a speed of hundreds of kilometers per second. In the course of movement, these atomic nuclei, reaching a maximum mass of 60 atomic units, are massively bombarded by a stream of high-energy neutrons (particles equal in mass to protons, but without an electric charge) emanating from the collapsing stellar core.

From time to time, a neutron, colliding with the nucleus of an atom, attaches itself to it; as a result of all this, a supernova explosion is accompanied by the rapid synthesis of more complex elements that are considered necessary for the existence of life, as well as many radioactive ones. Some of these isotopes have a half-life of only seconds, others, such as ⁶⁰Fe and ²⁶Al, decay in about the million years that it took to form our protoplanetary nebula, and the third, say ²³⁸U, there is a long way to go: they provide geological heating for billions of years. The superscript corresponds to the total number of protons and neutrons in the nucleus - this is called atomic mass.

This is what happens when Betelgeuse explodes. In a second, its core will shrink to the size of a neutron star - an object so dense that a teaspoon of its substance weighs a billion tons - and possibly become a black hole. At the same moment, Betelgeuse will erupt about 10⁵⁷ neutrinos, which carry away energy so quickly that the shock wave will tear the star apart.

It will be like the explosion of an atomic bomb, but trillions of times stronger.

For observers from Earth, Betelgeuse will increase in brightness over several days until the star floods its part of the sky with light. Over the next couple of weeks, it will fade, and then creep into the glowing nebula of a gas cloud, irradiated by a compact monster in its center.

Supernovae pale in comparison to the kilonous explosions, which occur when two neutron stars fall into the trap of mutual attraction and spiral into a collision Perhaps it is thanks to kilonovs that heavier elements such as gold and molybdenum appeared in space. … These two bodies are already inconceivably dense - each has the mass of the Sun, packed into the volume of a 10-kilometer asteroid - so their merger causes gravitational waves, ripples in the structure of space and time.

Long-predicted gravitational waves were first recorded in 2015 with a billion-dollar instrument called LIGO The first gravitational wave was recorded by the Laser Interferometer Gravitational-Wave Observatory (LIGO) in September 2015. the merger of two black holes at a distance of 1.3 billion light years from Earth. (Laser Interferometer Gravitational-Wave Observatory, "Laser-interferometric gravitational-wave observatory"). Later, in 2017, the gravitational wave arrived with a difference of 1.7 seconds with a burst of gamma radiation recorded by a completely different device - like a thunderbolt and a flash of lightning.

It is amazing that gravitational and electromagnetic waves (that is, photons) have traveled through space and time for billions of years, and it seems that they are completely independent of each other (gravity and light are different things), but nevertheless arrived at the same time. Perhaps this is a trivial or predictable phenomenon, but for me personally, this synchronicity of gravity and light filled the unity of the Universe with deep meaning. The explosion of a kilonova billion years ago, a billion light years ago, seems like a distant sound of a bell, the sound of which makes you feel like never before a connection with those who may exist somewhere in the depths of space. It's like looking at the moon, thinking of your loved ones and remembering that they see it too.

"When the Earth Had Two Moons" by Eric Asfog

If you want to know how the Universe originated, where else life can exist and why planets are so different, this book is definitely for you. Eric Asfog talks in detail about the past and future of the solar system and the cosmos in general.

Alpina Non-Fiction is giving Lifehacker readers a 15% discount on the paper version of When the Earth Had Two Moons using the TWOMOONS promo code.