The movie “Interstellar” — one of the most successful sci-fi movies in history — depicts the journey of Dr. Cooper through the boundless space to find a new habitat for mankind.
At first glance, the movie, featuring a light-speed spacecraft and an artificial planet, seems exotic and implausible; turning back our perspectives to our real world, however, Cooper’s journey may not just be an improbable sci-fi movie. The dramatic climate changes, rapid depletion of natural resources and extinction of organisms that our generation is undergoing all seem to reflect the devastated Earth that Cooper lives in the movie.
So what are the solutions? Should scientists send audacious astronauts to the distant, undiscovered space, to find our new Earth?
The answer: No, considering that we in 2020 do not have a light-speed spacecraft or an AI space pilot.
Yet, looking for habitable exoplanets like the ones in the movie is still possible and fascinating. Among numerous exoplanets that NASA has found, there are three planets that have the highest chance of life: which I am about to introduce for the future Dr. Coopers.
Gliese 887b, 887c
To begin with, the two planets in the Gliese 887 solar system, Gliese 887b and Gliese 887c, were found to be in the goldilocks zone — the ideal position of a planet to inhabit life — and thus have a great chance of being inhabitable.
Discovered by the RedDots team of the University of Göttingen, the Gliese solar system is located 11 light-years away from our sun, placing itself in one of the closest habitable planets from the Earth. According to the team, the central star, Gliese 887, is a red dwarf that is much dimmer and has a size half of that of our sun, meaning that the goldilocks zone is much closer than the distance from the Earth to the sun. Gliese 887b and 887c are the second and third closest planets of the system, which have orbital periods of 9.3 days and 21.8 days, respectively.
There are two distinct features that make these two planets an ideal choice for our new habitat. Most notably: lack of starspots. Unlike our sun, Gliese 887 has only a few starspots, indicating that it is mostly inactive.
Since the planet is mostly inactive, it rarely sends out a strong stellar wind that may sweep out the planets’ atmospheres. Thus, the researchers from the RedDots team suggest that there is a high chance that the planets will retain, or even have thicker atmospheres than the Earth.
In addition, the planets’ brightness is almost constant, according to the RedDots team. Such properties allow scientists to observe the atmospheres of the planets with greater ease, using the James Webb Space Telescope.
In addition to the Gliese solar system, Ross 128b has a great chance of life due to its similarity to our own Earth.
The planet is relatively new to our knowledge: it was only discovered in 2017 using the radial velocity detection method. According to Amber Jorgenson, a reporter from Astronomy.com, Ross 128b is only 11 light-years away from the Earth, a relatively close distance compared to other Earth-like planets. The close distance, however, is not the only thing that makes this planet so fascinating.
In the research done by Diogo Souto and his fellow researchers, Souto used the APOGEE spectroscopic instrument to analyze the chemical composition of the planet. The team identified the star’s abundance in aluminum, calcium, carbon, iron, magnesium, oxygen, potassium and titanium, according to Jorgenson.
Moreover, Souto used the data to estimate the core composition and the radii of the planet, which turned out that the planet has a larger solid core and a smaller radius than that of the Earth. The planet’s large core and relatively small size make it highly likely to have a rocky surface and lack a gaseous envelope, increasing the chance of life.
In addition, scientists have also claimed that Ross128b is highly likely to have a temperate climate, due to its location in its system. According to the data gathered from ESO’s High Accuracy Radial velocity Planet Searcher, the planet has the second-closest temperature to that of our Earth. The researchers further elaborated that “though the planet is 20 times closer to the sun than our Earth, the red dwarf star’s low temperature prevents it from having extreme temperatures.”
Finally, Kepler-452b, so-called the “Earth’s cousin,” holds its spot as one of the most likely planets to be habitable. As its name suggests, Kepler-452b was first discovered in 2015 by the Kepler satellite.
According to the Encyclopedia Britannica, the planet’s radius is only 1.63 times that of Earth, making it likely to have a rocky surface. However, scientists have also suggested a possibility that the planet may instead have a gaseous envelope like Neptune, which will significantly reduce its mass and thus gravity.
The star the planet is orbiting around, Kepler-452, is also similar to our system, as it is only 20% brighter and 1.5 billion years older than our own sun. Despite its similarities in its size and the host star, what makes the planet so intriguing is its distance and orbital period. According to Gregersen, the planet orbits around its sun at a distance of 156.5 million km, which is strikingly similar to our own planet’s distance from the sun, 149.60 million km.
As a result, Kepler-452b only receives 10% more solar energy than our Earth does. In addition, due to such similarity, Kepler-452b has an orbital period of approximately 384.8 days.
Scientists have suggested that the planet’s similarities in the orbital patterns and distance from the host star make it a strong candidate for our next habitat. Still, there exist some limits.
Most notably, the planet is 1400 light-years away from us, making it impossible for mankind to approach. In addition, Gregerson further implied the possibility that the rising luminosity of the host star, Kepler-452, may cause the “greenhouse effect,” depleting all liquid water on the planet.
Traveling to the three planets mentioned above may not be a matter of a close future. However, the perpetual efforts of scientists to discover and analyze new exoplanets will undoubtedly help us explore our vast, mysterious universe and further understand our home, the Earth.