We are used to the fact that on Earth day follows night, then day comes again. And in general, they are approximately equal in duration. But what if we change the conditions a little? Eternal day or eternal night, light and darkness only on one side of the planet. What will life be like in these worlds?
The first planet where the day does not end was invented by Isaac Asimov in the story “Nightfall”. The story actions take place on a planet called Lagash, where the day does not even last forever, but for two whole millennia. And only once every 2049 years does night fall on this planet.
The idea of the story itself was born during a conversation between Isaac Asimov and the editor of one of the most famous science fiction magazines, John Campbell. They discussed a quote by the famous American poet Ralph Emerson about what would happen if the stars appeared in the sky only once every thousand years.
Asimov’s idea caught on and in 1941 he wrote “Nightfall” – a story about a world where humanity has long calculated the date of its death. That’s just about the reasons for the destruction of civilization, people do not know anything, over the years they have forgotten everything. In this world, there is eternal day and one of the scientists finds out that the cause of the impending death of mankind will be the onset of darkness, which is unknown to people.
Many consider Asimov’s story one of the best in his work and it’s hard to believe that it was written by him at the age of 21, when the writer was just starting his creative career. In 1990, Asimov and Robert Silverberg developed the idea to a full-fledged novel and in 2000 the image of Lagash appeared in the “Black Hole” movie.
But back to the planet itself. Lagash is located in the system of six stars and only in very rare cases do the luminaries converge so that one of the hemispheres of the planet plunges into darkness.
Could such a planet really exist?
Asimov, like a real science fiction writer, still inspires scientists to conduct research. Last year, astrophysicist Sean Raymond, a US scientist, decided to investigate the Lagash system. Sean is not just an amateur – he has a dissertation on the formation of Earth-like planets and the dynamics of planetary systems, so he knew from which side to approach the issue.
As a result, he first realized that the model of the six-star system shown in the story could create conditions for a continuous day lasting only a couple of months, and not a couple of thousand years. He began to experiment, creating with the help of a computer system after system, similar to the one shown in the “Black Hole”.
And it turned out that a planet with an eternal day may well exist, only for this it is necessary to have in the system just a black hole.
The whole point is that not only the planet must circle around the star, it must also be inside the ring of six stars. But also all together they must circle around the black hole located in the center of the system. This is what Asimov’s world might look like:
But with such an arrangement, night could never come in this world at all. In general, Raymond came up with 5 versions of the Black Hole star system and realized that for the arrival of night in the story and the movies, two large satellites, similar to our Moon, must rotate around the planet.
Under this condition, once every several hundred years, depending on a plurality of factors, night could fall on the planet.