That something happens to the Sun and an expedition has to be prepared to save us from the catastrophe is something that is usually a topic for Hollywood. That happens in Sunshine , a 2007 film directed by Danny Boyle, who was the director of that little gem of zombie movies that was 28 days later . The film narrates what happens to the crew of a ship that must prevent the death of the Sun by launching a nuclear bomb with the mass of the island of Manhattan and in this way “restart” the nuclear reactions that keep it shining. Years before, in 1990, the Japan/America Picture Company produced Solar Crisis , a film in which the inexhaustible Charlton Heston appeared. In this case, scientists managed to predict a solar flare so intense that it threatened life on Earth and to avoid it, the Helios spacecraft had to launch a nuclear bomb equipped with an artificial intelligence named Freddy to control the explosion. And since this could not be trusted -and if not ask Bowman about HAL 9000 in the 2001 film- he is also accompanied by a Japanese pilot who, as a space kamikaze, is there as a plan B so that the bomb explodes right in when the explosion will occur.
And in 2006 the TV movie Solar Attack warned us that a huge solar mass ejection from the corona, the outermost part of our star’s atmosphere that can be seen with the naked eye during total solar eclipses, was threatening to burn -literally- the atmosphere of our planet due to the methane that exists in it. The solution, once again, was to detonate nuclear bombs, but this time not at the Sun but at the poles of the Earth. This would release water vapor into the atmosphere in large quantities and put out the fire as soon as it started. Come on, the solution of the classic The burning colossus but to the beast.
We can learn two things from these movies: that the writers solve everything by force of nuclear bombs and that we should be cosmically distressed in case our Sun starts doing weird things, like explosions or flares.
From cinema to reality
A preview of what could happen happened in March 1989, when a huge sunspot caused eruptions to appear on the surface. These explosions, caused by the magnetic field that created the spot, launched a shower of subatomic particles into space, essentially protons. Upon reaching Earth, and as they are charged particles, they move following spiral paths guided by the magnetic field of our planet, which sometimes causes the appearance of electrical currents induced in high-voltage lines . Thus, at 2:45 a.m. on March 13, a particularly intense eruption activated the differentials of the James Bay power station and caused the electrical collapse of the entire province of Quebec, Montreal included, leaving 7 million people . The network recovered around midnight that day. Of course, the inhabitants of the darkened Canadian city were able to enjoy some beautiful northern lights.
This is not the only effect of solar flares, which modify the properties of the ionosphere for days. All radio communications fail, as well as artificial satellites , and microchip factories are also affected. The economic cost is significant: a single solar explosion like the one that extinguished Quebec caused losses of tens of millions of dollars and an indirect cost of 2,000 million. Solar flares have also been responsible for radar interference during World War II and the loss of contact with the McMurdo Antarctic base in November 1960, which left it incommunicado and without the possibility of help because there was no way of knowing the local weather conditions.
Danger, nearby supernova!
However, if there is something to be afraid of, it is another type of cosmic explosion, supernovae. It is difficult to imagine, but they are like this: a star that ends up shining like 100,000 million stars.
What is it that leads to dying in such a catastrophic way? To understand it, we must bear in mind that the life of a star is a continuous struggle against its own gravity , which tends to concentrate all the mass in the center. The only way to prevent this is to use the energy released by the central nuclear furnace, which converts hydrogen into helium. But what happens when you run out of hydrogen? In the case of the Sun, it will die slowly and without too much fuss, but for stars with much more mass, the situation is totally different: when the hydrogen is finished, the core contracts enough to increase the temperature and start the combustion of helium, which forms carbon.
When the helium fuel tank approaches the reserve, the core contracts again to increase its temperature until the fusion of carbon and helium into oxygen, as well as other elements such as sodium, magnesium… carbon from the core, all over again: the core contracts and it is the turn of oxygen, which produces silicon and sulfur. In this way the star acquires the characteristic structure of onion layers: a dense core made up of heavy atoms covered by successive layers of oxygen, carbon, helium and hydrogen.
At the moment when the fusion of silicon begins to produce iron, the fate of the star is cast . This trip lasts only one day and ends with a spectacular explosion that our galaxy witnesses every 50 years: the supernova. The core of the star collapses in a brutal way: to get an idea, let’s imagine the Earth compressing to the size of Madrid or Barcelona in less than a second . This collapse causes the outer layers to shoot outwards at thousands of kilometers per second and causing such a brightness that the star emits, in a few weeks, as much energy as the Sun in its last 4.5 billion years of existence.
The danger that it entails is the X and gamma radiation that such an explosion entails and that if it happens too close, less than a hundred light-years away, something that happens, on average, every 240 million years. If that were to happen today, gamma rays would cause nitrogen and oxygen molecules high in the atmosphere to break apart, turning them into nitrogen oxides, which would destroy the ozone layer . And it goes without saying what would happen on the earth’s surface if we ran out of the ozone layer…
Do we have candidates nearby? Definitely. The one with the most ballots is Betelgeuse , located at a dangerous distance of 197 light-years. But we can be calm: astronomers estimate that it will explode within a few hundred million years. Let’s hope they’re not wrong.
References:
Cohen, R. (2010) Chasing the Sun, Random House
Gehrels, N.; et al. (2003). “Ozone Depletion from Nearby Supernovae”. The Astrophysical Journal. 585 (2): 1169–1176. doi:10.1086/346127.
