The phrase, "out of this world," means not only "off planet Earth" but also,

figuratively,

A

on another planet's moon

B

going outside the atmosphere.

C

vie

visiting Mars and beyond.

(D

above and beyond the usual.

B. going outside the atmosphere.

Explanation:

Outer space, or simply space, is the expanse that exists beyond the Earth and between celestial bodies ... Intergalactic space takes up most of the volume of the universe, but even galaxies and star systems consist almost entirely of empty space. Outer space does not begin at a definite altitude above the Earth's surface.

No, they don't believe there's an end to space. However, we can only see a certain volume of all that's out there. Since the universe is 13.8 billion years old, light from a galaxy more than 13.8 billion light-years away hasn't had time to reach us yet, so we have no way of knowing such a galaxy exists.

Outer space is not completely empty-it is a hard vacuum containing a low density of particles, predominantly a plasma of hydrogen and helium, as well as electromagnetic radiation, magnetic fields, neutrinos, dust, and cosmic rays.