You'll never get across the universe.

The light astronomers study is billions of years old: it takes a long time to reach us from such great distances.

Because you can never travel faster than the speed of light, you will never be able to get to the source of a star's light before it reaches us here.

Many of the stars astronomers study have exploded and no longer exist, but their light hasn't reached us yet. We can never physically travel to those locations as we perceive and understand them because it means we would need to go backwards in time.

We can never catch up to the expanding edge of the universe.