Question

How is the size of the universe estimated?

Answer 1

46.5 billion light years according to Wiki
https://en.wikipedia.org/wiki/Observable_universe

Explanation:

This means that if you were to jump in a spaceship that could travel at the speed of light (which none can do now) it would take you 46.B billion years to cross the universe - truly ginormous! But its continuing to expand too.