A more thorough explanation:

universus

Universe means everything that exists, including all matter and energy, the planets, stars, galaxies, and all the contents of intergalactic space.

• The universe is vast and contains billions of galaxies.
• Scientists are still trying to understand the mysteries of the universe.
• Our solar system is just a tiny part of the universe.

The examples illustrate the definition of universus by showing that it refers to everything that exists, from the smallest particles to the largest galaxies. The universe is all-encompassing and includes everything we know and everything we have yet to discover.