Btukfyl

Dust cloud.

The star may be residing in a dust cloud with no other stars nearby. This interstellar dust will create a faint nighttime glow, and can be thick enough that no other star's light can be visible on the planet.

Perhaps their planet is on the inside of a giant Dyson sphere that was created by an ancient civilization.

This would be a vast solid shell that surrounds their entire solar system, the inside of which is covered with solar panels in order to collect as near as possible to 100% of the energy output of their sun. Naturally, this would block their view of the rest of the galaxy as well.

As for why the ancient civilization who built it left this one planet on the inside, that's up to you to decide. Maybe they saw that it had some life forms that might potentially develop intelligence some day and didn't want to just kill them off, so they left them where they were, while dismantling all the rest of the planets in the system to build the spere?

One possibility is for the surface of the planet to be covered in highly luminous matter. Perhaps all the surface is an interconnected network of bioluminescent life.

There is no moon (assumed because you make no mention) and the high levels of light pollution at night will blot the stars out.

You could combine with a naturally hazy atmosphere and cloud cover to a) further blot the stars and b) reflect all that light pollution back to the surface, further brightening it at night.

Normal urban terrestrial light pollution (before and during the great 2003 Northeast Blackout) to give you an idea:

there are many ways. especially if it's just you don't see the stars.

there could be a constant storm like on Jupiter and in 'All Summer In a Day' by Ray Bradbury.

Venus has an atmosphere made up mainly of carbon dioxide, and thick clouds of sulfuric acid completely cover the planet.

basically, clouds covering the entire planet would do the trick.

'light pollution' would also make it so the stars can't be seen because the ground is so bright.
Night Sky in Las Vegas Which is always full of light especially at night

vs the Idaho dark sky preserve

The sun takes up about half a degree in Earth's sky. Stars are less than one ten thousandths of that. If atmospheric blurring were to blur a star one hundredth of a degree, their light would be spread over an area hundreds of times larger, making them practically invisible, while the effect on the sun will be minuscule.

It is never night.

https://www.tripsavvy.com/midnight-sun-in-scandinavia-1626397

Your people live on the north pole of a tidally locked planet. Like the countries near the north pole on our planet, in summer the sun never sets. It is always summer for your people.

Why do they only live near the pole? Maybe it is hot farther south. Maybe there are scratchy monsters. Maybe there is no land to live on.

Maybe they are afraid of the dark.

The laziest answer is to just wait a while. If you wait an incomprehensibly-long while, eventually the expansion of the universe will move all currently near-by light generating bodies outside of our visual distance.

In other words, civilizations in the far-future may never realize that anything other than their own sun exists, because nothing else is close enough to interact with anymore. This video has a nice overview:

https://www.youtube.com/watch?v=Qg4vb-KH5F4

It's part of a rogue solar system ejected from any galaxy, somewhere in the middle of a large intergalactic void.

No stars would be visible until the inhabitants developed sufficiently powerful telescopes to be able to see the faint light of distant galaxies.

Is it possible for a planet in our part of the galaxy to have a night without stars?

It depends on what you mean by "our part" of the galaxy. If you point yourself in the direction of Sagittarius and travel a mere 2600 light years you will find yourself smack in the middle of the Great Rift, which is the dark patch you see covering the Milky Way.

https://earthsky.org/clusters-nebulae-galaxies/the-great-rift-in-the-milky-way

This is an area where new stars are formed, but obviously the dust is thick enough that we cannot see through it in the visible spectrum. It seems plausible that there could be star systems in that large area where the dust is thick enough that no other star is visible.

Note that the "thick" dust is by Earth surface standards extremely dilute and would be considered a high-quality vacuum. It's only the fact that there are light years of the stuff that make it hard to see through.

It is the basis for a society that develops into the modern age without an interest in outer space.

You might wish to research how the "space cloud" and "planet that doesn't know about space" tropes have been done before. https://tvtropes.org/pmwiki/pmwiki.php/Main/SpaceClouds and https://hitchhikers.fandom.com/wiki/Krikkit may be useful.

The sun is a star, but I know what you mean. Here are some other options:

• Multiple suns (such as Asimov's "Nightfall")


• One sun, and many moons


• Large amounts of very white (or reflective) dust, which reflects sunlight around the atmosphere.


• Underground or underwater societies.


• Regular volcanic eruptions causing volcanic ash in the atmosphere (or anything else in the atmosphere)


• Monsters that come out at sunset


• taboo/superstition/religion


• Your planet might be near a black hole, causing gravitational lensing, an accretion disk, unusually high speed orbits, and jets coming from the poles.