Or if they entered a region of dust or gas that had a temperature differential to the sphere.
If fact, I just realized that if any such structures like Ringworlds existed, they would be trivially easy to spot if they were at the right aspect to us. It would look like a star with either a band across it, or like the star had a single ring. The ring on the far side of the star would also be tremendously bright (if angled to our solar system slightly) and much easier to spot with a telescope that blocked off the light of the central star.
Stars are too bright and too far away and the ringworld too thin (at least I think there would be stability problems if they were built too wide, but I don’t know enough). Worse, I thought the way we were trying to detect planets these days was by looking at the gravitational effect the planet has on the star. But wouldn’t a ringworld balance out its own gravitation effect on the star?
Might we be able to see them if they went in front of galaxies or other highly luminous body?
Come to think of it, wouldn’t they look a lot like black holes?
Not really. The black hole might have hawking radiation it should also gravitationally lens the surroundings more than a dyson sphere.
It might also have an accretion disc.
Or if they entered a region of dust or gas that had a temperature differential to the sphere.
If fact, I just realized that if any such structures like Ringworlds existed, they would be trivially easy to spot if they were at the right aspect to us. It would look like a star with either a band across it, or like the star had a single ring. The ring on the far side of the star would also be tremendously bright (if angled to our solar system slightly) and much easier to spot with a telescope that blocked off the light of the central star.
Just an OT thought.
Stars are too bright and too far away and the ringworld too thin (at least I think there would be stability problems if they were built too wide, but I don’t know enough). Worse, I thought the way we were trying to detect planets these days was by looking at the gravitational effect the planet has on the star. But wouldn’t a ringworld balance out its own gravitation effect on the star?
The Kepler Observatory also detects planets by masking the light from the star and then looking for any bright spots (Coronal Masking).
Even more advanced telescopes will use this technique in combination with the gravity wobble. There are also diffraction and coronal masking.
http://www.iop.org/EJ/article/0004-637X/662/1/738/65461.web.pdf
http://spie.org/x24241.xml?ArticleID=x24241
why did I get down voted on that post?