Dealing with huge space scale

I am working on a 3D space game and I would love to be able to go to new planets, stars and maybe even galaxies without changing scenes. Now one brilliant program that does this is Space Engine.

I've been trying to fit a star system inside the limits of unity world space, but even at a small scale, the outer planets are too far away from the center.

I wonder if someone knows how programs like space engine deal with huge scale and if it is possible in Unity