the universe is filled with countless other worlds among the thousands of exoplanets discovered beyond the solar system none can yet be considered more hospitable to us than Earth with some melted by the unbearable heat of nearby Stars others are forever encased in ice or scorched by devastating radiation but among the many inhospitable worlds there are others that are quite different there are Great Waters of oceans and rivers on their surface clouds float across their sky and showers and thunderstorms rage in their atmosphere perhaps these worlds can become the cradle for beautiful and unique life as has once happened on the earth and today we're going to visit some of the most remarkable of them [Music] it can hardly be disputed that life is one of the most amazing complex and mysterious phenomena in the universe despite the fact that we' have been studying it for thousands of years many important questions about it still remain unanswered and the greatest among them is how widespread is biological life beyond our planet at this point we cannot yet say with a satisfying degree of certainty whether the Earth's biosphere is a unique phenomenon or whether it has emerged as a natural and logical result of continuous Evolution it is hardly surprising that the search for life beyond Earth is one of the most important fields in science and in order to identify the most promising celestial bodies in this respect the so-called Earth similarity index or ESI is used it is based on two main parameters the level of gravity on the surface of a Celestial body and its equilibrium temperature it is these parameters according to scientists that determine how much the other world can be similar to Earth and how favorable the conditions on its surface are for hypothetical life the undeniable advantage of the ASI is its Simplicity because when an exoplanet is discovered you can usually determine its approximate orbit mass and size and this information is just enough to calculate the basic parameters of the [Music] index however for all its appeal it does not take into account many factors critical for sustaining life therefore we will allow ourselves to be as presumptuous as to formulate our own evaluation system taking the ESI as the basis and supplementing it with several important parameters the activity of the parent star can be singled out as one of them it is known that frequent flares and stellata ejections characteristic of red dwarves can adversely affect the stability of the atmosphere and radiation background of the nearest exoplanet [Music] nevertheless red dwarves are considered more favorable than large stars like Sirus or Vega because the lifespan of giant stars is too short and the radiation is too destructive leaving no chance for potential life to develop the most favorable ones are orange and yellow dwarves including our sun the probability of tidal locking is another significant factor to be reckoned with this probab ility depends on the distance between an exoplanet and its star celestial bodies located too close to their Stars permanently face them with one side only as a consequence there is a large temperature difference between their day and night hemispheres too great a distance from the source of heat and light puts the planet outside the habitable zone which drastically reduces the chances of the Genesis of life it is also necessary to consider the type and chemical composition of a given exoplanet because in order to develop hypothetical life requires a certain set of chemical elements in combination with characteristic relief such conditions can be seen on Rocky terrestrial type planets or super Earths many Neptunes meanwhile do not have Solid Surfaces and ocean planets are deficient in many elements [Music] thus the set of parameters we have specified allows us to comprehensively assess how favorable the conditions on a given exoplanet are for hypothetical life for example in a scheme like this the earth looks extremely attractive against these parameters being the natural Benchmark for other objects at the same time Mars although it has the highest similarity index to our planet in the entire solar system has a number of obvious disadvantages it is too cold too low mass and demonstrates a significant water deficit Venus on the other hand despite appearing very similar to Earth on the face of it is too hot because of the strong Greenhouse Effect and although most of its parameters are in the green zone the extremely high temperature is a critical disadvantage of the planet effectively cancelling out all its advantages thus there are no planets within the solar system sufficiently similar to Earth to be considered favorable for life however Beyond its boundaries more than 5,000 other worlds orbiting distant stars have already been discovered and in many respects some of them can be considered similar to our planet one of these objects closest to us is an exoplanet known as gisa 1002b it is located just 15. 2 light years from our planet it was discovered in 2022 using the radial velocity method this method is effective for finding relatively close exoplanets and involves capturing subtle fluctuations of the parent star caused by the movement of space objects around it the exoplanet is located near a small and dim red WF known as gisa 1002 its radius is only 14% that of the Sun and its mass is 8 times smaller than that of our star given that gisa 102 has a surface temperature of just 3,000 Kelvin or about 2,730 de C it is not surprising that it's Luminosity is extremely weak it's about 700 times weaker than the sun's observations also show that the object is quite Serene which is unusual for stars of this class due to the low Luminosity of this red dwarf its habitable zone has an extremely small radius and width however the object gisa 1002b is located near its Outer Edge and can be considered potentially habitable according to observations this Celestial body completes a full orbit around the center of its system roughly every 10 Earth days consequently the average radius of its orbit is clearly very small and is about 0. 046 astronomical units it is assumed that because of the extreme proximity to the parent star the exoplanet is likely to be tidily locked facing it with one side at all times calculations show that the celestial body receives 1 and a half times less energy from from its star than Earth does from the Sun and its average surface temperature could be approximately 230 kelv or 43° C below zero incidentally it is slightly warmer than Mars given tidal locking and a possible greenhouse effect this means that liquid water could be found on the exoplanet surface and thus there may be conditions for sustaining life at least some terrestrial organisms are able to survive in such conditions calculations also show that the mass of glya 102b is 8% greater than that of our planet and the radius exceeds the Earth's radius by only 3% using the data it is not difficult to determine the acceleration of Freefall on the surface of the celestial body it practically does not differ from the value way used to thus the combination of all known factors suggests that gisa 1002b is a rocky planet most of which is covered with ice due to its size which is very near to that of the earth it has a rather High ESI of 86 and in our scheme this object would look like [Music] this at the same time modeling of the planet's climate shows that its illuminated hemisphere can receive enough energy to Port an ocean of liquid water with archipelagos of islands or even fully fledged continents also tidal deformations caused by the nearby star warm up the planet's interior so the existence of an ocean hidden under the ice even on its night side shouldn't be ruled out incidentally gisa 1002b is not the only planet in the system it was discovered alongside another object dubbed gisa 1002 CA which is located a little further away namely at a distance of 074 astronomical units from Center a full annual rotation takes this exoplanet 21 days and its mass exceeds the Earth's by about 36% the object receives four times less energy from the parent star than our planet does from the Sun so the temperature on its surface is quite low just about 188 82 K or 91° C below 0 if we use the previously developed scheme then this exoplanet will look like this it can be assumed that the conditions on the surface of giso 1000 and 2C are close to those observed on the satellites of Jupiter or Saturn increased volcanic activity caused by the planet's high mass could lead to the formation of a hidden ocean with warm and salty water rich in many chemical compounds hypothetically life could also develop in such conditions possibly in highly unusual and unexpected forms of course among the great variety of known exoplanets much warmer and more favorable worlds can be found such for example is the planet k272 e located 27 1 light years away it orbits a small red dwarf about four times less massive than our star its radius is 33 of the solar radius and its temperature is relatively low reaching 3,360 K or about 3,100 de C observations made by the Kepler orbiting telescope showed that the exoplanet crosses the disc of the parent star every 20 24 days this means that the radius of its orbit is very small and is about 0.
1 astronomical units which implies that the celestial body is located within the habitable zone and can be considered potentially favorable for harboring life according to the received data it is also suggested that k272 may be tidily locked or in orbital resonance like Mercury despite the star low Luminosity the exoplanet receives 11% more energy than Earth does from the Sun assuming that the atmosphere of k272 e is similar to Earth's the average temperature on its surface should be about 295 K or 22° C above zero which is slightly warmer than on our planet at the same time it is worth remembering that if the celestial body is tidily locked there is a high probab ility of extreme temperature variations between the day and night hemispheres in addition to this it must be taken into account that its parent star like most other red dwarves is erratic and is often observed to flare up and emit great amounts of Stellar matter which can be detrimental to the atmosphere and surface of nearby space objects calculations show that k272 e is 29% larger in diameter than the Earth and is about 2. 2 times more massive knowing this we can calculate the level of gravity on the surface of the celestial body it is about 32% higher than we're used to thus with all the known data taken into account we can assume that this exoplanet is more likely than not a rocky superar where liquid water and a dense atmosphere can be found its Earth similarity index is quite High and is . 87 and in our scheme this object will look as follows planets of this type are expected to have a wide variety of chemical elements and their relief should be smooth and favorable for the origin of Life undoubtedly the frequent flares of a nearby star pose a tangible threat to the atmosphere but a powerful magnetic field will hypothetically deflect Stellar Wind particles and the oceans will protect the their inhabitants from this destructive radiation in this case we can assume that on K2 72e it is possible to observe incredible auroras by far more impressive ones than on our planet as for the hypothetical biosphere that could develop on such a planet it would likely be markedly different from Earth's a different spectrum of incident light might Force local plants to use alternatives substances of photosynthesis so their leaves would likely be purple or reddish in color in addition excessive radiation hazards may be an obstacle for life forms to venture on land alternatively it may lead to the evolutionary formation of Defense adaptations such as thick skin or specific cellular structures similar features are known to manifest themselves in some terrestrial organisms such as tardigrades ARA and some fungi meanwhile in addition to this planet so attractive in many respects three other planets have been discovered in the system two of them dubbed k272 B and k272 C are located very close to the parent star and are slightly larger than our Earth it is assumed that due to the emissions and Stellar Wind of the nearby star they are devoid of any atmosphere and are similar to Mercury the third planet K2 72d is estimated to be comparable in size to earth and its orbit has a radius of about 08 astronomical units it completes a full orbit around the center of the system approximately every 15 days and is located near the inner edge of the habitable zone because of its high temperature conditions on its surface are likely to be close to conditions on Venus and the probability of the Genesis of life is extremely low in any case research on this system is still going on which means we have much to learn about it in the future incidentally all the objects we have looked at here are similar in size to the Earth however life is known to be able to adapt to a wide variety of conditions including High Gravity which is inevitable on massive planets if we travel about 1,800 light years away from the solar system we can find a yellow dwarf with parameters very similar to those of our sun it's called Kepler 452 and it's a main sequence star just 3.
7% more massive and 11% larger than the sun in 2015 an extremely remarkable exoplanet named Kepler 452b was discovered near this star using the TR Transit method High Precision measurements allowed us to calculate that is located at a distance of 1. 04 astronomical units from the center of the system and completes a full annual rotation every 385 days this location renders the probability of tital locking of the celestial body extremely low which is undoubtedly a favorable factor according to the available data the object Kepler 45 2 B is about 5 times more massive than our planet and its radius is about 1. 5 times bigger than Earth's this means that the acceleration of Freefall on the surface of the celestial body is 2.
