This is a drawing by my daughter which inspired one of the elements in my story/world:
The perspective is a little bit mixed here (certainly I don't have a 15 meter-high volcano in this world), but for the sake of this question let's assume that such planet is between 1 and 2 kilometres in diameter or 500-1000 meters in radius. Planets like this are sold by various agencies in the world of my story.
Given the fact that the whole story is set in exactly the same universe, as ours (only a little bit into the future), with exactly the same physics and other laws, the question is, if such planet:
- could exists naturally (what are the limits here) or
- these companies are selling artificial creations.
What is the smallest possible planet that can exists naturally in our universe? Must I assume that such small planets cannot exist naturally?
Edit: Here are some answers to the questions given in comments. In short, think about compressing Earth to as smallest size as our current physics allows.
- The planet must be habitable, with gravity as close to Earth's one as possible.
- Any round rock orbiting the sun or other stellar body does the trick. Meeting IAU's or other definitions is not needed.
- Buildings required. Other stuff as well. Full recreation of Earth's look & feel very welcome. This should be private planet as we now understand a private island.
- Escape velocity and other physical, chemical or geological parameters as close to the Earth as possible. So, again, a rock in space, not a small gas body.
- Again, circling the Sun or other stellar body. No comets lost in space, please. Light and day-night conditions and yearly seasons as close to Earth as possible, please.
- No rain, snow or clouds needed, though nice to have. Breathable atmosphere is a must.
- This should be a habitable planet, but for a single person or a small group of people. As you can see in the image, we don't need more than 3-5 story buildings. So the fact that breathable atmosphere would be as thick as 500-1000 m above the ground isn't necessary a problem.
- Extremely dense core sounds like a good idea, but that might ruin the "as close to Earth physics as possible", if I am not mistaken. And it would also most likely fail under "habitable", as we would need some underground water sources etc.
- A black hole in a center of a planet certainly sounds good as long as above conditions are met.
- Asteroid might work as well as long as above conditions are met.
The planet must be habitable and easily accessible. So, if by any mean, planet's atmosphere would be filled with some orbiting rocks or other space trash, disallowing any easy navigation and landings, then this is out of question.
The company wants to sell a fully-featured product, where you can spend the rest of your life. Not just a rock in space, that you can show off on your pictures, but that you cannot land on and live on.
