Scientists confirmed Earth is not our ultimate home since the discovery of superhabitable planet so-called ‘Kepler 442b’ announced by NASA in 2015.
It is pretty reasonable to assume that Earth is the ultimate Eden the universe that can flourish the emergence and evolution of living things. We’ve got a thick atmosphere filled with oxygen and nitrogen that we can breathe. The planet is large enough that it’s still molten in its core, with a rotating ball of iron that maintains the planetary magnetic field. After all, not only it is the only planet we know life has evolved, but it’s also considered our home, the place where many ancient histories have been conserved for millennia. However, as it turns out, Earth is merely a known example of an inhabited planet among the immense universe, so many astronomers have been focusing on the Earth-like planet for the search for alien lives. But what if there are alien worlds that are even more habitable than our Earth. These so-called ‘superhabitable planets’ are intriguing many astrobiologists, especially Rene Heller at McMaster University in Hamilton, who is specialised in exoplanet detections, planet formations, and planetary habitability.
A superhabitable planet is a hypothetical type of exoplanet that may be better suited than Earth for the existence of mortal beings. The concept was launched in 2014 by Rene Heller and John Armstrong. They stated that a circumstellar habitable zone on superplanets is not enough to define a planet’s habitability, in which a planetary surface that is capable of supporting liquid water will give an adequate atmosphere to accommodate life. While still assuming the world requires water, they hypothesised that Earth may not represent the most optimal planetary habitable condition for the maximum biodiversity. Whereas they define a superhabitable world as an extra-terrestrial planet could support the flourishing and reproduction of diverse flora and fauna than there are on earth.
Furthermore, Heller and Armstrong clarified one of the key factor underlying habitability, which is the amount of tidal force caused by the gravitational pull from neighbouring moons and the sun. Tidal heating can drive plate tectonics, accumulate excessive carbon dioxide, and produce the kind of deadly greenhouse atmosphere that found on Venus. Indeed, tidal heating can be great enough to melt the super-Earth, or at least forming volcanism on par with Jupiter’s moon, lo. Researchers found that tidal force is also capable to fully disintegrate the crust on planetary rocky body. “Dimming their prospect for habitability,” Jackson said.
Other worlds might have more surface area and greater mass than that of Earth, processing wrinklier surface or larger diameter. For sizes, it is required to be about two times of Earth’s mass, and 1.3 times of Earth’s radii, in which to provide an optimal size for the plate tectonics. With the larger in dimension, it would have a greater gravitational attraction that would increase the retention of gasses during the process of planetary formations. It is therefore likely that they have a denser atmosphere, thus offering a greater concentration of oxygen and greenhouse gases. A heavier atmosphere will raise the average temperature to optimum levels for the maintenance of plant life, 25 °C (77 °F), also influence the surface relief by decreasing the volume of the ocean basin, which would improve the diversity of marine life in shallow waters.
Heller and Armstrong proposed that to identify a habitable planet, the environmental conditions should be more suitable for biocentric rather than anthropocentric. The optimum temperature for Earth-like life is unknown, although it appears that Earth organism diversity has been better in warmer periods. It is, therefore, possible that exoplanets’ atmospheric temperature is slightly higher than that of the Earth, which is more hospitable for species’ lives.
Other factors to consider are the classification of the central star in the system. Studies suggested that Earth lies near the inner edge to the habitable zone of our Solar System, and that may harm its long-term liveability. The size and luminosity of our main-sequence star (the Sun) increase over time that has been pushing the habitable zone outwards. K-type stars are less massive than the Sun, and are stable in the main-sequence for a longer time (20 to 70 million years, compared to 10 billion for the Sun of G-class star), thus giving more time for the emergence and evolution of life.
Kepler- 442b is a super-Earth, an extrasolar planet that was described as being one of the most Earth-like planets in term of temperatures and conditions, yet found. The planet was discovered by NASA’s spacecraft using the transit method, in which the periodic dips of distant star brightness are resulted from exoplanets regularly passing by. According to the discoveries of two investigators, Kepler 442b would likely be larger, warmer and older than the Earth, orbiting K-type main-sequence stars.
It was announced as being located within the habitable zone of its star, a region where liquid water could exist on the surface of the planet. Kepler- 442’s axial obliquity, in which case it would not have tilt-induced seasons as Earth and Mars do, its orbit is perhaps close to circular, hence it also lacks eccentricity-induced seasonal changes like those of Mars. “One review essay in 2015 concluded that Kepler-442b, along with the exoplanets Kepler-186f and Kepler-62f, was likely the best candidates for being potentially habitable planets.” (Wikipedia, 2020)
The researchers concluded that the superhabitable planet Kepler 442 will tend to orbit the Orange Dwarf star in Alpha Centauri B system, which is estimated slightly older than our 4.6 billion years Solar system at anywhere from 4.8 billion to 6.5 billion years old. If life on planets or moons surrounded Alpha Centauri has evolved similarly as it did on Earth, the primitive form of life has been possibly flourishing there earlier on.
So far, astronomers have sought to conclude based-conditions of the superhabitable Earth-like planet to determine Kepler-442b as being our neighbouring extrasolar planet. However, they have not yet detailed any data about the world’s plate tectonic or its general ocean-land fractions. All in all, the researchers have still been detecting another potentially liveable place for the next human migration, yet, they still need solidary supports from the public and Congress.
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Available at: https://en.wikipedia.org/wiki/Kepler-442b[Accessed 11 July 2020].
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