Extraterrestrial civilization may be traveling in space on a 'rogue planet' without using a spacecraft
interstellar navigation in which humans and aliens with advanced civilization move between stars may appear, but with the technological capabilities of the earth civilization at the time of writing the article, it moves from the solar system to another planetary system . Takes an enormous amount of time. Regarding such interstellar navigation, Irina Romanovskaya, an astronomical scientist at Houston Community College , said, 'It is possible that advanced extraterrestrial civilizations are navigating interstellar using'free floating planets ' instead of spacecraft. There is. '
In science fiction works,
Migrating extraterrestrial civilizations and interstellar colonization: implications for SETI and SETA | International Journal of Astrobiology | Cambridge Core
Civilizations Don't Even Need Space Ships to Migrate From Star System to Star System --Universe Today
Humans have rapidly developed their technological capabilities, but it still takes five years for the spacecraft to reach Jupiter's orbit with the technological capabilities at the time of writing the article. Interstellar navigation is a very long story, as even Proxima Centauri , the closest star to the solar system, is at a distance of four years, even if it travels at the speed of light. In a study that considered 'How many crew members are needed to send a manned spacecraft to a Proxima Centauri planet?', A spacecraft made with technological capabilities as of 2018 will take 6300 years to reach the planet. The results showed that at least 98 crew members needed to connect generations on board the spacecraft.
However, Romanovskaya said that highly developed extraterrestrial civilizations may use 'rogue planets' that are gravitationally freed from stars and other celestial bodies, rather than using spacecraft for interstellar navigation. Insist. 'We suggest that extraterrestrial civilizations may use rogue planets as an interstellar vehicle to reach, explore, and colonize the planetary system,' said Romanovskaya. ..
Rogue planets away from stars, such as the Sun, for the Earth are often considered dark, cold, and uninhabitable due to the lack of light and heat of the stars. However, in some cases, geothermal heat is generated due to the decay of radioisotopes even on rogue planets, and there is active geological activity, and there is a possibility that liquid water and atmosphere are maintained on the surface of the planet. Romanovskaya also points out that advanced civilizations can deliberately change the environment of rogue planets and develop energy sources to make them suitable for sustaining life.
study suggests that there could be as many as 50 billion rogue planets throughout the galaxy, with particles in addition to the cases where the original planets are released by stellar gravitational events. In some cases, it is formed by accretion that accumulates on heavy celestial bodies. It is also possible that planets are emitted from celestial bodies located outside the planetary system, such as the Oort cloud in the solar system.
Romanovskaya proposes 'four scenarios' in which extraterrestrial civilizations use rogue planets for interstellar navigation.
◆ 1: Use a rogue planet that happened to pass by
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In fact, Scholz's Star , 17-23 light-years away from the solar system, is calculated to have passed outside the Oort cloud about 70,000 years ago, and it is possible that another celestial body will grab the edge of the planetary system. It's possible. If there is an advanced extraterrestrial civilization exposed to some extant threat, predict the location of rogue planets around the planetary system and board when passing relatively close to interstellar navigation. It is not impossible to use it.
Sedna , a trans- Neptunian object with a very long orbital period of 76 astronomical units even at the near future , as an example, and uses a celestial body with a very long orbital period to go out of the planetary system. Claims that there is also. 'This would be possible for a very advanced civilization that is already exploring the planetary system to a distance of at least 60 astronomical units from the stars,' said Romanovskaya.
◆ 2: Bring rogue planets close to their planet
A well-technical extraterrestrial civilization can also select prominent planets from the Oort cloud-like celestial bodies and use propulsion systems to guide them closer to their inhabited planets. If you have enough time, you can build underground shelters and other infrastructure, change the atmospheric composition, or create from scratch to make rogue planets more livable.
Of course, if you forcibly pull a distant planet into the planetary system, the orbits of other planets may be confused. However, if the expansion of the star has already begun and the civilization has moved to the outside of the planetary system with the change of the habitable zone, the effect may be mitigated.
◆ 3: Use a dwarf planet with a very long orbital period
◆ 4: Use celestial bodies ejected from the planetary system
When a dying star expands, at some point celestial bodies on the outer edge of the planetary system may escape the gravitational constraints of the star and be released out of the planetary system. If advanced extraterrestrial civilizations can accurately predict the timing, they can prepare in advance to board a rogue planet and search for another star away from the dying star.
All of the above scenarios do not consider rogue planets as 'permanent homes', but rather lifeboats. 'In all of the above scenarios, rogue planets may not serve as a permanent means of escaping existential threats,' said Romanovskaya. 'As internal heat production declines, such The planet will eventually be unable to maintain a sea of liquid water. '
Rogue planets are ejected from the planetary system, so they have less resources available than planets that orbit around stars, and there are no seasons or day and night. 'Therefore, instead of making rogue planets a permanent home, extraterrestrial civilizations use them as an interstellar means of transportation to reach and colonize another planetary system,' Romanovskaya said. increase.
There may also be extraterrestrial civilizations that colonize the entire galaxy by repeating interstellar navigation by rogue planets, not just to escape existential threats such as star death. In this case, the parent civilization will create a unique and autonomous child civilization in different planetary systems.
Romanovskaya said that if extraterrestrial civilizations use rogue planets for interstellar navigation, there are some technical traces such as cyclotron radiation and unnatural infrared radiation due to the interaction between the solar sail and the interstellar medium. Pointed out the possibility that there is. Romanovskaya argued that it might be possible to know the existence of extraterrestrial civilization by detecting these traces from rogue planets.
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