NASA recently announced that the Transiting Exoplanet Survey Satellite (TESS) has discovered a "super-Earth" numbered TOI-715 B, with a radius 55% larger than that of Earth and only 137 light-years from Earth. Analysis has revealed that it may have liquid water on it. Astronomers published their findings in the Monthly Notices of the Royal Astronomical Society [1].
According to the new study, the host star TOI-715 is a smaller and fainter red dwarf star than the Sun, with a mass and radius of less than a quarter of the Sun's and a surface temperature of only 2,800, which is 2,700 degrees lower than the Sun's surface. Since the star is relatively faint, if there is a planet with an orbital radius similar to that of Earth, it will inevitably not receive enough stellar energy and become a frozen planet.
The exoplanet TOI-715 b discovered this time is close enough to the star, at a distance of only 12.4 million kilometers, and it only takes 19 to make one revolution3 days. Operating in such an orbit, the TOI-715 B is just in the habitable zone, even according to the most pessimistic estimates.
Studies have shown that TOI-715 B has a mass of 1 of Earth's55 times, which means that it is a rocky planet, and the surface is mostly made of rock like Earth, so it is a super-Earth. Considering that this super-Earth orbits in a habitable zone, this means that its surface has the right temperature to sustain the presence of liquid water.
According to current theories, liquid water is considered to be the key to life. At present, human beings only know that there is life on Earth, and life on Earth originated in the ocean, so when we are looking for extraterrestrial life, we will pay more attention to exoplanets that may have a large amount of liquid water.
Analysis shows that the star TOI-715 is 6.6 billion years old, 2 billion years before the formation of the Sun. In such a long period of time, the super-Earth of TOI-715 B may have given birth to life, and there was plenty of time to form a civilization.
If there were sapient species on TOI-715 B, then their civilization level would have reached an extremely high level, far beyond the current level of humans. With the current technology of human beings, we can discover the existence of TOI-715 B, then the TOI-715 B civilization can also discover the existence of the earth, and even have the ability to visit the earth through interstellar navigation.
Cosmologist Stephen Hawking has always been cautious about extraterrestrial civilizations. Hawking believes that contact with extraterrestrial civilizations may lead to unwarranted disasters on Earth, just as Native Americans did with Europeans, and the result is misery.
Of course, it is also possible that TOI-715 B did not give birth to intelligent species, or even life, at all. The birth of life should be an extremely accidental event, and the emergence of intelligent life and civilization is even more accidental among accidents.
If time were to be repeated, there would not be intelligent species like humans on Earth. On Earth 65 million years ago, dinosaurs were the rulers of the earth, and the ancestors of humans were very weak mammals, living in the shadow of dinosaurs.
Later, a giant asteroid crashed into the Earth, causing a drastic change in the global climate and the extinction of a large number of animals and plants, including the dinosaurs that ruled the Earth for more than 100 million years. Only after the extinction of the dinosaurs did the human ancestors have more room to live and continue to evolve.
Or if the climate of the African continent had not changed, and the ancestors of human apes had not been forced to survive, they would not have left the forest and come to the ground, so they would not have learned to walk upright, their hands would not have been freed, and their brains would not have developed rapidly, so that later Homo sapiens and their civilizations would not have appeared.
At the moment, it is unrealistic for humanity to visit this super-Earth, 137 light-years away. The distance of 137 light years is equivalent to 1,300 trillion kilometers, and even at a speed of 100 kilometers per second, it would take up to 410,000 years. Even at a speed of 100,000 kilometers per second, it still takes 410 years, far more than a person's lifetime.
Interstellar travel will only become a reality when traveling at sub-light speeds. According to the time dilation effect of special relativity, if the spacecraft can travel at a speed of 86 of the speed of light6%, the time on board the spacecraft will be doubled, and for a spacecraft, it will take only 79 years to fly 137 light-years away.
If the speed of the spaceship can reach 99 of the speed of light9973%, for a spacecraft, it takes only 1 year to travel to 137 light-years away. But for people on Earth, the flight time of the spacecraft is almost 137 years. If the spacecraft arrives at TOI-715 B, which is 137 light-years away, and immediately turns around and returns home, when the spacecraft returns to Earth, the people on the spacecraft feel that only two years have passed, and the time on Earth is already 274 years later, which is the time dilation effect.
References
1] georgina dransfield, mathilde timmermans, amaury h m j triaud, et al. a 1.55 r⊕ habitable-zone planet hosted by toi-715, an m4 star near the ecliptic south pole, monthly notices of the royal astronomical society, 2024, 527, 35-52.