I’ve spent many years extolling the virtues of life on a cold brown dwarf moon. Similar to the Galilean moons of Jupiter, a moon orbiting a sub-brown dwarf would be warmed internally by the tidal forces generated by its proximity to such a powerful gravitational force. Additionally, the sub-brown dwarf itself might provide some local heating, or at least an abundance of charged-particle strewn local magnetic fields to energise the sub-stellar environment. So, a habitable environment on a moon seems a likely scenario. If a cold, dark sub-brown dwarf were to be found orbiting the Sun at a great distance, then it neatly provides the grounding for extraterrestrial life on our doorstep (1).
This seems to me to be the simplest scenario for life in a sub-brown dwarf system. There are complexities – tidally-locked moons (2), lack of light, and so on. But the basics are there.
Another exotic possibility is that the sub-brown dwarf itself might harbour life. The complex cloud systems in these failed stars can contain layers which are at room temperature, and abundant in water and other chemical goodies which could form the building blocks of life. A team of astronomers from Edinburgh University have been considering this very point, wondering whether very simple life might be able to get going in the clouds of a cold brown dwarf (3). This life might arise in two ways – either somehow evolving from scratch in the cloud environment, or originally being seeded into it by an impacting asteroid or comet. Either way, conditions for life might be good, except for the lack of a solid surface to dwell on:
“Floating out by themselves in the Milky Way galaxy are perhaps a billion cold brown dwarfs, objects many times as massive as Jupiter but not big enough to ignite as a star. According to a new study, layers of their upper atmospheres sit at temperatures and pressures resembling those on Earth, and could host microbes that surf on thermal updrafts...Observations of cold brown dwarf atmospheres reveal most of the ingredients Earth life depends on: carbon, hydrogen, nitrogen, and oxygen, though perhaps not phosphorous.“ (4)
These ideas build upon work done by the late, great Carl Sagan (with his Cornell colleague E. E. Salpeter) on the potential for life in the clouds of the gas giant Jupiter, first considered back in the 1970s (5). They envisioned giant ‘floaters’ filled with hydrogen bobbing through the Jovian atmosphere, tiny ‘sinkers’ and self-propelled ‘hunters’ which had evolved from the lazy floaters (6). All very speculative, but presented in Dr Sagan’s inimitably compelling fashion. Read More…
Book review: ‘The Sagan Conspiracy’ by Donald Zygutis
Subtitled “NASA’s Untold Plot to Suppress the People’s Scientist’s Theory of Ancient Aliens”
New Page Books, 2017
Carl Sagan was one of my heroes when I was growing up. His hit TV show ‘Cosmos’ was truly inspiring. Probably one of the reasons why I was drawn to science in the first place. My copy of his eponymous book was a school prize, still on my shelves. He came up with some great ideas, many of which were highly imaginative and, let’s be honest, pretty speculative. It was part of his broader appeal to push the boundaries of possibility, particularly regarding the potential for extraterrestrial life.
Later in his life, he seemed to become more conservative, more sceptical, more apprehensive about the darkness of superstition. These are natural changes as people age, of course. I assumed that Sagan had lost that early zest, but I was wrong. Having read this revisionist book, I realise now I was wrong about several things.
I always knew that Sagan had collaborated with the Russian scientist I. S. Shlovskii on a book entitled “Intelligent Life in the Universe” back in 1966, but I was unaware of the so-called Stanford Paper, which is the central plank of Zygutis’s book.
The full title of Sagan’s 1962 Stanford Paper is “Direct Contact Among Galactic Civilizations by Relativistic Interstellar Spaceflight”. It pre-dated Erich von Däniken, and beat Zecharia Sitchin’s 1976 book “The Twelfth Planet” by a country mile. How could that possibly be important, given the way Sagan seemed to vilify pseudo-scientists later in his life? Read on…