On a different world with six Suns, darkness never falls. Such is the story of Isaac Asimov’s Nightfall.
Life around a single star is the only one known to us. It’s easy for us to believe that if we were to find life elsewhere in the Universe, it would be around a single star, Sun-like at an earth-like distance from it. That’s like finding a lost item beneath the only street light on the road because that’s where the light falls!
Science fiction is filled with life on planets in a multiple star system, the most notable being Star Wars featuring Tatooine, a planet with two host stars. Is this possibility so incomprehensible? Here are the latest headline discoveries in the last 5 years alone:
- Planet Like ‘Star Wars’ Tatooine Discovered Orbiting 2 Suns
- We’ve Discovered a Binary Star System Whose Planet Is in Stable Orbit
- The First Binary Star System With More than One Planet
- Twin Planets Found Around Twin Stars
- Wikipedia list (ever-growing!) list of discovered circumbinary planets
Pretty convincing, eh? In fact, when I found out that more than 50% of stars in our Galaxy are binary stars, I was thrilled. Binary stars are basically two stars orbiting each other. Heck, the nearest Sun-like star (second nearest star) is a part of a binary system. It doesn’t end there. NASA’s planet hunter space telescope Kepler has found more than a 1000 exoplanets, of which half the planets are around binary systems.
Detailed theoretical studies and simulations have found that binary systems may have a better chance of producing life on its planets than those in single star systems like our own. Now that this concept isn’t so strange anymore, let’s be bold and see what the six sun-system in Asimov’s Nightfall has to offer us.
Nightfall’s story takes place on a planet called Kalgash which revolves around six stars! At any given point of time and location on the planet, there is at least one Sun in the sky (in the worst case, which is rare itself), shining brightly. As you can imagine, people on Kalgash have never known a sky without a single sun in it. Therefore, they don’t know what darkness is!
They don’t even know what the stars and other planets are! The concept of darkness and stars are as abstract to them as nothingness is to us. They are truly terrified of the dark. However, based on the exact way the planet orbits around the six suns, the entire planet plunges into darkness every 2049 years and [spoiler alert] their civilization collapses into extreme madness. On the day before the nightfall, expecting the arrival of darkness, a scientist from the story comes up with this crazy idea of life around just one star. It goes somewhat like this briefly:
Scientist: Imagine there are other suns like ours in the Universe but so far away that they become faint and are outshone by the light of our mighty suns. But they can manifest themselves during the darkness which is bound to come tomorrow.
Others: That’s crazy. Our six suns, planet Kalgash, that’s all there is to the Universe!
Scientist: Perhaps not. But just imagine, if those other suns also had planets orbiting around them, much like ours. Imagine, if there is a planet around just a single star. And life exists on it.
Others: You are taking it too far. We know from our own planet that having six suns is the only natural way for life to exist. It can’t be!
Scientist: One example proves nothing. If such a planet exists around a single star, as it rotates, it will experience half a day of light followed by half a day of darkness!
Others: That’s just crazy. Life just can’t exist on such a planet, because it has constant periods of darkness in it. And we on Kalgash require a constant source of light to function.
Yet, here we are on planet Earth, around our dearly Sun. The above is the genius of Isaac Asimov, who used the story concept as grounding to explain to us how foolish we are to expect life to form on only Earth-like systems. Nature often works its magic in incomprehensible ways.
I started reading Nightfall and I was amazed at the six star system that was imagined by Asimov. The next day, I was attending my Astrophysics lecture, when suddenly the projector shone big & loud to read “Castor is a six-star system and the second brightest star in the constellation Gemini!” As I said, Nature is working its magic.
Now comes the best part:
PS: The featured image above shows an artist’s impression of a triple sunset seen from the super-Earth Gliese 667 Cc.
The brightest star is the red dwarf Gliese 667 C, which is part of a triple star system.
The other two more distant stars, Gliese 667 A and B appear to the right.
Astronomers have estimated that there are tens of billions of such rocky worlds orbiting faint red dwarf stars in the Milky Way alone!
The star Gliese 667 C could host at least 7 planets and 3 of those, all rocky planets (including Gliese 667 Cc), are potentially within the habitable zone i.e could host life!
*Imagination runs wild*