(Continues along the premise of this question: Creating a second earth: How to make a continent?)

So, thanks to their helpful team of ask forum buddies, 😉 the terraformers designing New Earth have completed the continents and made the planet habitable. Hooray!

BUT, when they look up into the sky on their first night, OH NO!!! The stars are all wrong! Remember, New Earth is an exoplanet in a different solar system than earth, and therefore its view of the night sky is entirely different. So, given that the inhabitants of this world need to find it indistinguishable from the old world, what can be done to make the night sky resemble that of old earth when seen from the surface?

  • $\begingroup$ Wouldn't this only be an issue for migrants? locally born residents would know no other sky. This same issue would be experienced by people migrating on earth from say Europe to Australia. $\endgroup$ Feb 2, 2023 at 21:26
  • $\begingroup$ Are we looking to be accurate enough to fool astronomers, or just good enough that the average person won't be put off? $\endgroup$
    – jb6330
    Feb 3, 2023 at 17:25

3 Answers 3


Artificial sky dome

The people can create an artificial sky dome with the proper star constellations and brightness to match the night sky seen from the Earth.

This can be done by using a combination of projectors and lighting systems to simulate the appearance of stars and other celestial objects.

It would also be important to simulate the motion of the stars and adjust for the planet's position in its own solar system.

The artificial sky dome could be designed to cover the entire visible sky from the surface and match the changing night sky over time, creating a seamless illusion for the inhabitants.

Space-based mirrors or reflective materials

Another solution would be to use space-based mirrors or other reflective materials to direct and reflect the light of specific stars in the direction of the surface. This would allow for a more natural-looking night sky, as the light from the stars would appear to come directly from the stars themselves.

Additionally, the position of these mirrors could be adjusted over time to simulate the changing night sky. Another option could be to install planetarium-style domes in various locations on the surface, which could project the desired night sky for viewing by the inhabitants.

Combination of lighting systems and computer simulations

A more realistic solution would be to use a combination of lighting systems and computer simulations to recreate the night sky.

The lighting systems could be positioned and calibrated to mimic the appearance of stars, with the brightness and position of each light source adjusted to match the desired constellation patterns.

Computer simulations could be used to accurately track the positions of the stars and other celestial objects, and to provide a realistic representation of the changing night sky over time.

This solution would require a significant investment in technology and infrastructure, but would provide a realistic and convincing representation of the night sky for the inhabitants.


You are trying to solve a non-problem.

The vast majority of human population today lives in cities, where the night sky is obfuscated by artificial lights. A random sample of these people will have no or very little memory of what the sky looks like back home, and they won't notice.

And defining the shapes and names of the new constellation can actually make them feel more home, similarly to what we do when we hang a poster or place a plant in a new house.

  • $\begingroup$ Well, quite a lot of people still know what is Ursa Major and how to find the Polar Star with its help. Even if this would take place in a very distant future where constellations would change from their current shape, some people would still notice that there's no polar star at the sky's northern pole. Thus a conspiration theory would arise, I read the question as a means to avoid the mob from ever producing a conspiracy theory that could be proven by observations. (For that though, he'd need to emulate/replace palaentological fossils and more, not just the starry sky.) $\endgroup$
    – Vesper
    Feb 2, 2023 at 13:39
  • 1
    $\begingroup$ Despite the night sky being obfuscated by artificial lights, it doesn't mean no stars are ever visible. Stars are, even in cities. And even in many stars aren't visible in cities, many people still travel to places with less light pollution. Whether it's for vacation, or just because their jobs take them outside of the cities outside daylight hours (farmers, sailors, truck drivers, etc). And even if 99.9% of the people would never notice, that 1 in 1,000 which does can be a major problem if the goal is that no one is going to notice. $\endgroup$
    – Abigail
    Feb 2, 2023 at 19:23
  • $\begingroup$ The other question is about terraforming and sculpting a planet to superficially resemble Earth, not about making it precisely identical in every detail to Earth. As far as most people are concerned, just having a sky with a similar distribution of stars meets a similar standard. For those few who are able to see the difference...so what? They can at least come up with new constellations, unlike the geologists, paleontologists, archeologists, etc, who are stuck with artificial landforms carved out of a dead planet. $\endgroup$ Feb 3, 2023 at 0:25

Augmented Reality

Place implants in the heads of the inhabitants. Those implants generate altered perceptions of reality, from the user interface for cars, microwaves or the Internet up to changing the perception of the heavens. You just edit the real night sky out of their perception and add the "real" night sky in. If you are worried that people might find it creepy, don't. The memories of the existence of the implants can be removed as well. So can their appearance in any scan. If a new child is borne, the automated implant factory sends an implant and hijacks nearby medical staff to implant it. You don't even have to be clandestine about that, just make everyone witnessing the operation not care and forget about it afterwards.

This tech will help you with many more problems you will encounter. Archiological digs? Paleontology? Your perception tells you that your ground penetrating radar found Roman ruins, you and everyone sees the artifacts and everyone can see them in museum. Win-win-win.

Why not go for a fully digital world? Good question, but either your group is eccentric or it just doesn't matter resource wise or this is cheaper computationally.

I'll let you work out the other implications of mind machine interfaces with write read access yourself.


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