We can have an intuition of what we would have over our heads on a clear night if in the summer months we look towards the east, where the Milky Way cuts the horizon: we will be contemplating the heart of our galaxy, located in the constellation of Sagittarius.
The truth is that, as in the cities, the tranquility of the outer neighborhoods contrasts sharply with the frenetic activity of the center. In this case, we have it densely populated with stars and gas clouds that move at speeds that reach more than three and a half million kilometers per hour and that are at 10 million degrees Celsius. At such a temperature the gas emits a large quantity of X-rays . If it were not because the possibility of developing cancer drastically increases, we would have free X-rays for life … But this would not be the least of our problems. We know that there are almost a thousand X-ray sources in a space of 400 by 900 light-years, mostly white dwarfs, neutron stars, black holes, and extremely hot gas clouds.
Now, even if it turned out to be the paradise of astronomy, we would not last an hour alive on the surface. Gamma radiation – which we create in nuclear reactors – floods space with an energy 250,000 times greater than that of visible light. It is radiation that comes from the annihilation of an electron with its antimatter twin, the positron, at an inconceivable rate: ten billion tons of antimatter are consumed every second. Such a “monster” has been dubbed the Great Annihilator.
We do not know what it is, although that antimatter factory is probably a black hole hidden behind a huge gas cloud. If we look carefully – and quickly – we can even see where it is: just where, in opposite directions, two matter geysers 5 light-years long are emerging.
