According to the arguments of Italian astronomers, the safest region of the universe is located in the middle of the Milky Way. The picture shows the sky over the Uruguayan countryside, about 185 kilometers north of Montevideo, on Feb. 5, 2021.
Italian astronomers have identified the safest region in the Milky Way galaxy, and the Earth is located just at its edge. According to this study, perhaps someday in the future, scientists will look for planets outside the solar system that are suitable for human existence based on this.
To find these habitable planets, it is necessary to first understand what characteristics they have.
Habitable planet characteristics
There are many conditions that must be met for a planet to be habitable. For example, planets need to be located in the “Goldilocks” region, where they are orbiting stars that do not have too much or too little heat and activity. And the planet also needs to be far from the deadly radiation in the universe.
These radiations can come from supernova explosions or gamma-ray bursts in the universe, which can not only kill all life as we know it, but can even strip away entire planetary atmospheres due to their release of dangerous high-energy particles that approach the speed of light. Scientists say that life is unlikely to survive on planets near the regions of these explosions.
Riccardo Spinelli, lead author of the new study and an astronomer at the University of Insubria in Italy, said, “The (impact of) intense cosmic explosions on life in the galaxy cannot be ignored.”
He told Live Science that life on planets very close to this big bang could be destroyed there.
The study points out that the Earth’s Ordovician extinction event, about 450 million years ago, may have been caused by a gamma-ray burst. Although there is no specific evidence linking a specific gamma-ray burst to this extinction event, the authors believe that this hypothesis is possible given Earth’s position in the galaxy.
A safe place to live in the Milky Way
Astronomers believe that a habitable place in the Milky Way would first have to be located in a region where there would be no massive radiation outbursts. According to astronomers’ calculations, this location is in the middle region of the Milky Way, and Earth is just at the edge of this region.
Each of the small pictures above (except the first one) shows in red the region of the universe where the Earth is located.
Astronomers point out that in the early Milky Way, the galaxy was affected by the violent movements of stars as they took shape, when violent cosmic explosions often occurred, but in the outermost regions of the galaxy, where stars are rare, the situation was much better, and big explosions occurred rarely.
Until about six billion years ago, most of the galaxy experienced explosions frequent enough to destroy life. But as the galaxy aged, such explosions became less and less frequent.
Today, the middle region of the galaxy, from 6,500 light-years from the galactic center to about 26,000 light-years, has fewer big explosions and is the safest region for life.
Outside of this region, near the center of the galaxy, life is less likely to survive in this region because violent explosions and other events from supernovae (near-terminal stars) are still common. Also the periphery of the intermediate region, where Earth-like planets (planets with silicate rocks as the main component, such as Earth) are rare and gamma-ray bursts are more frequent, is also uninhabitable for life.
The solar system is about 26,000 light years from the center of the Milky Way, just on the edge of the safe region of the galaxy referred to above.
Steven Desch, an astrophysicist at Arizona State University who was not involved in the study, told Life Sciences that at first glance, the conclusion seems reasonable.
“I’m pleased to note that they do seem to put [the study] in a rigorous framework and have realistic expectations of what a gamma-ray burst would produce. The study also explains factors that one might forget, such as the fact that gamma-ray bursts release energy and matter that varies in all directions.” Desch said, “I haven’t looked closely at their numbers, but at first glance they look reasonable.”
The new research was published in the March issue of Astronomy and Astrophysics. Perhaps in the future humans could search for habitable second homes in these regions of the galaxy.
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