Biohabitable zone
People often ask: Is there life not only on the surface of our earth, but also under the warm crust and on the top of the cold iceberg, but also outside the earth? Scientists believe that the answer should be yes. They called places of life outside of Earth "life settlements" and believed that life colonies could only occur on Earth-type planets and corresponding moons, such as Mars, Europa, Europa, Enceladus, Enceladus, and Titan in the solar system.
The term "livable zone" first appeared in 1959. In 1992, James Kestin of Pennsylvania elaborated on it: the living zone is the space region around the star, and the surface of the planets in the area should have liquid water, and such an area can only exist on the planets around the "solar-type star". In our solar system, the inhabited area is located between Venus and Mars, which is not too hot or too cold, and is the "golden orbit" zone. Planets closer to Venus are too hot, too dry, and not too far away, and planets like Neptune are too cold for life to survive.
The location of the inhabited area depends on the size and temperature of the star with the planetary system, and is generally located outside the star. The hotter the star, the farther away the habitation area is, and the wider it is. The habitation zone also depends on the planet's atmosphere, and if there is a large amount of heat-trapping greenhouse gases around a planet, such as carbon dioxide, the planet can be maintained farther away from the star. In addition, it is also hoped that there are disks of gas or dust around the star, otherwise there is no "raw material" for forming planets. Planets also need to have a long-term stable climate and an appropriate proportion of chemical composition after formation, as well as a magnetic field to protect themselves from deadly high-energy particles from other planets in space. For Earth-sized planets, life may also require a massive planet as a "gravitational vacuum cleaner" to clear the way for Earth-sized planets to avoid cosmic impact events like the 1994 "Sumek-A-Ray Star" impact on Jupiter.
For the origin and survival of life, it is necessary to maintain continuous habitability on geological time scales.
For this reason, astronomers choose only low-mass main-sequence stars as habitable planets. Such stars are like the sun, so life's Noah's Ark should go around "sun-type" stars. More than 130 planets have been discovered outside the solar system, but unfortunately, apart from Earth, not a single planet with a living shoulder has been found. It is estimated that within the Milky Way, there are 1 million to 1.5 million stars with planetary systems around them, and these stars are not immutable, and stars will age due to evolution. As the star gets older, the luminosity increases, which pushes the habitation zone outward.
In extreme cases, the entire settlement could be moved outside its location, leading to the misfortune of all life on planets that had already formed an inhabited area! Fortunately, during most of the star's life, star aging has little effect on the inhabited area, does not affect the existence of the inhabited area, and does not change much even when their inner and outer edges change with their luminosity.
Human understanding is in tune with the times, and so is the thinking of scientists. In the second half of the 20th century, a series of discoveries were made in the study of life in the universe, which challenged conventional wisdom and gave scientists a leap forward in their understanding of residential areas. 10 years ago, scientists discovered microbes on the seabed, which were considered incapable of life, including exotic crabs, clams and strange tubeworms, as well as bacterial colonization. Here are some super heat-loving microorganisms,
It lives around or in hydrothermal fluids at 117°c near submarine craters, and relies on scaly luminescents erupting from craters. They are resistant to extremely high pressures and highly corrosive acids, and can withstand high doses of radiation exposure. In addition to the presence of strange organic matter on the seabed, a variety of primitive life, including superherost microorganisms, have been found beneath the warm crust of several meters deep and on the top of the cold iceberg. Superherost microorganisms, unlike organic matter that breathes oxygen, get energy in that they don't need organic molecules or sunlight, but instead get their energy by temporary metabolic action. There are cellular molecules of RNA in all organic matter on Earth, and each RNA has a unique chemical sequence, and the two relatively close RNA have a similar RNA sequence.
Therefore, based on a large number of more representative organic matter, scientists can make a familiar "tree of life" on Earth, and surprisingly, the "roots" and lowest "branches" of the tree of life are occupied by super-heat-loving microorganisms. This gives scientists an inspiration: life may originate from super-heat-loving microorganisms, and under harsh life conditions, tenacious organisms can survive. So outside of traditional settlements, liquid water can also support life; if a giant planet has a lot of internal energy to provide heat, it does not need to be close to the sun, and it can have enough energy to maintain biomass on a surface without light.
Even if all of the above is available, after the discovery of an Earth-sized planet in an appropriate orbit, careful consideration of the habitation area of the new world will need to be considered. Therefore, while searching for new planets outside the solar system, it is also necessary to conduct in-depth research on the life of Noah's Ark that has been discovered. Some people expect that the mission to discover new planets will be basically over in 10-25 years, and because of the long distance of extrasolar planets, ground-based telescopes cannot see items the size of 1 meter there, so the second mission falls on the heads of space scientists. Space scientists are preparing to launch large space telescopes, including the European Space Agency's Darwin (DARWIN) and NASA's Earth-type Planet Discoverer (t=pf).