Solar systems are the smallest of the three systems in question. A solar system consists of a star such as the sun and the objects affected by its gravity.
A star is a luminous ball of gas mostly hydrogen and helium
A Nebula is a cloud of gas and dust in outer space, visible in the night sky either as an indistinct bright patch or as a dark silhouette against other luminous matter.
stars die because they exhaust their nuclear fuel. Really massive stars use up their hydrogen fuel quickly but are hot enough to fuse heavier elements such as helium and
there is no upside-down in space you can't go upside down in space
