The concept of cosmic pluralism is by no means a modern-day fantasy. It dates as far back as the ancient Greeks, with ancient scholars such as Anaximander and Epicurus who proposed the idea that there could be other worlds in the cosmos. It has also entertained the minds of Immanuel Kant, John Locke, and Benjamin Franklin.
In modern times, having entered space, landed people on the moon, and successfully sent drones to Mars, they have a much greater understanding of the galaxy and have found lots of potentially inhabitable planets in the solar system and beyond. Proxima B is a recently discovered planet and the subject of discussion among astrobiologists looking for life beyond Earth.
Discovery and Physical Attributes of Proxima B
Proxima Centauri B orbits the red dwarf star Proxima Centauri, the closest star to the sun. It is a similar size to Earth and about 4.2 light years away, making it one of the nearest exoplanets. It was discovered in 2016 using Doppler spectroscopy instruments.
The exoplanet orbits its sun every 11 Earth days and is around 20 times closer to its sun than the Earth is to the sun. It is unknown how old the planet is and there are no signs to indicate Proxima B has any moons.
Does Proxima B Tick All The Boxes for Sustaining Life
The planet has some interesting physical attributes. It is in a habitable zone, meaning that it is far away enough from its host star to allow water to pool on the planet’s surface. However, its equilibrium temperature is estimated at around -39 degrees Celsius, receiving around 65% of the Earth’s irradiation.
We don’t know what its physical surface features, whether it is fully covered in ice, has planet-wide oceans, has dry land, or a combination like people have on Earth.
Planetary Necessities for Life to Exist
There may be some planets that can accommodate life, but even then, there are varying degrees to what kinds of life forms the planet is suitable for. A planet in the habitable zone with forms of liquid can, at the very least, sustain partial microbial life.
These life forms include bacteria and microbes that are necessary to establish the conditions to allow animals and plants to evolve. It is estimated that the Earth was only habited by such microorganisms 3.7 billion years ago, a long time before animals and plants appeared.
Microbial life would have to evolve to form ecosystems that can nourish animals and human-like sentient forms of life. Before that could happen, though, there are certain conditions that must be met for microorganisms to develop and thrive on planets outside Earth.
Temperature and Planet Climate
Where there is a possibility for liquid water to form, there is a chance for life to develop. Celestial bodies can be covered in oceans or they can even have subterranean oceans such as Europa or Enceladus, moons of Jupiter and Saturn. Those two moons both have icy crusts with subsurface water bodies that could harbour life, but thus far there have been no indications either moon has had life forms.
The temperature will vary depending on the distance and how much radiation it receives from its host sun. The temperature will determine the climate and the landscape of the planet.
Atmosphere, Gravity and Protective Magnetic Fields
Another reason why Proxima B is not feasible for life is because it does not have a stable atmosphere. The atmosphere would protect the planet from excessive radiation and provide conditions for which essential elements such as Oxygen, Nitrogen, Hydrogen and Carbon can build. Without these elements, life is highly improbable.
If the celestial body has enough mass and radius, it will have a natural gravitational pull. The denser and larger the mass, the stronger the pull. This, alongside magnetic fields, will protect the atmospheric conditions and keep them stable.
Potential Suspects for Life Outside Earth
Studies have been made about numerous planets and moons in the Solar System that could support life. The moons of Europa and Enceladus, mentioned earlier, have been examined from afar by scientists in astrobiological studies for their potential to sustain life. Closer to home, Mars has also been the subject of much discussion.
Since 1996, there have been missions to Mars, and in 2021, the Ingenuity Mars Helicopter entered the surface of Mars and flew across the Red Planet. This breakthrough gave a greater understanding of the history of the planet and also revealed a potential biosignature for life on Mars.
Is Life Possible Beyond Earth – The Looming Question
Space exploration is not confined to studies and observations of astronomers. In recent years, space tourism has become extremely popular. You may have heard of companies such as SpaceX, Blue Origin, Axiom Space, and Virgin Galactic, run by Elon Musk, Jeff Bezos, Kam Ghaffarian, and Richard Branson. These companies have all entered the space tourism market, offering flights into space for the general public. Needless to say, such ventures are extremely expensive and will set you back a good $50 million, if not more, but it has made the idea of space colonisation more tangible.
The economic potential for space colonisation would be immense. If life were possible on a nearby planet, then there would surely be opportunities to mine valuable resources that could have a major impact on the world economy. It may be decades before astrobiologists can find a planet with the suitable conditions to sustain human life, but in the meantime, there will be more missions, and every decade seems to bring a breakthrough in space exploration.