A supernova is one of the most destructive events in the universe.
Almost all the mass from the outer shells of the star is ejected into interstellar space, and from the remaining matter, depending on the mass of the star, a neutron star or a black hole is usually formed.
Supernova is a rare and beautiful phenomenon (if, of course, you look at it from afar).
When Kepler's supernova burst out 400 years ago, 11,000 light-years from Earth, it was visible even during the day! Now the remnant of that supernova is one of the most beautiful nebulae.
Supernova remnant Cassiopeia A (Kepler's supernova).
But what happens if a supernova breaks out near us?
Here it is necessary to clarify the concept of "next". The Universe is huge and “nearby” can mean both in the neighboring Galaxy and near the nearest star.
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There is not a single star in the vicinity of the solar system that could become a supernova in the future.
Moving on, the situation changes.
The closest of the most likely supernova candidates is Betelgeuse.
Betelgeuse - Alpha Orion (upper left shoulder). Below the image of the star in the photo are the dimensions of the star / Earth's orbit / Jupiter's orbit, respectively, with the same scale.
The red giant with a luminosity of more than a hundred thousand times that of the Sun and a mass of 15-17 solar masses is located at a distance of 600 to 800 light years from us.
Placed in the center of the solar system, Betelgeuse, will fill all space up to the orbit of Jupiter!
A snapshot of the Betelgeuse disk (ALMA, ESO telescope complex).
Apparently, the star is in the final stage of evolution and is likely to end its life in the near future with a grandiose supernova of the second type.
It will be a grand astronomical event.
The degree of its influence on the Earth strongly depends on where the axis of rotation of Betelgeuse is directed.
There are two possibilities.
First: the star's axis of rotation is not directed towards the solar system
In this case, the apparent brightness of the star as a result of the explosion will increase by 10-12 thousand times. In place of the left shoulder of the constellation Orion, a bright point of the color of incandescent glass will appear, shining almost like the full moon.
Supernova Betelgeuse in the night sky as seen by the artist.
Gradually decreasing the brightness, within a couple of years Betelgeuse will become invisible, and in the future astronomers will be able to observe a planetary nebula in its place.
Second: the axis of rotation of the star is directed towards the Earth
Then a much brighter flash awaits us. Betelgeuse will shine brighter than the full moon, turning the night into twilight.
If Betelgeuse's axis of rotation is directed towards the Earth, then it will become the brightest object in the sky after the Sun!
The earth will be "overwhelmed" with a stream of gamma rays. Thinning of the planet's ozone layer is possible. The strongest auroras will reach mid-latitudes and further south.
The strongest auroras will spread across the planet.
But despite the spectacularity of the event, the distance to the star is too great for the outbreak to cause significant harm to the biosphere.
However, if a potential supernova is significantly closer than Betelgeuse, for example, three to five light years from Earth or closer, an explosion with a 99% probability will destroy at least all terrestrial life.
A nearby supernova explosion is likely to destroy much of life on Earth.
True, the chances that the Earth will be so close to the Supernova in the foreseeable and even quite distant future are extremely low!
The likelihood of supernovae in the Galaxy is estimated at one or two per century or even lower. The probability that this will happen close to Earth is orders of magnitude lower.
At least something close enough (at a distance of 200-300 light years), judging by the traces of iron-60 in the sediments, exploded as much as 3 million years ago.