It seems you are referring not to any collapsed star, but a black hole. The "event horizon" is the area from which nothing can escape.
That refers specifically to black holes (there are other types of "collapsed stars"). This sphere is called the "event horizon".
Only around a black hole. There is a sphere around every black hole where light orbits the black hole.
No, it isn't. It's the ball of rock itself, the earth. We got "lithos" from the Greek for stone. The lithosphere is the stone sphere, or the earth.
No you can't. I've allready cleared the game and there is no light sphere.
Imagine a light bulb in the center of a sphere. It emits a fixed quantity of light. That's how much light will reach the sphere. The concentration of light per unit of area, on the sphere, will depend upon how large the sphere is. And the area of a sphere is proportional to the square of the radius of the sphere. So the intensity of the light will be inversely proportional to the square of the distance which it has to travel. It is effectively illuminating a larger sphere (even if there is no actual sphere, the principle remains the same).
A black hole.
The photosphere.
The photosphere.
Black holes are invisible because their gravity well pulls in any light around it, but technically they're not stars. They are the collapsed cores of stars.
a globe
The photon sphere is a sphere above the event horizon in which light orbits the black hole.
darkness is produced in absence of light darkness is produced in absence of light