Question

Do astronomers know how many galaxies are in the universe?

Answer 1

No,they don't.

Explanation:

Because there far too many galaxies in the universe. All the telescopes, even the most powerful ones can only look up to the outskirts of the observable universe which is just `1/5` parts of the universe. There are simply too many to know the exact number, plus many are hidden in the dark matter, or behind other galaxies. There are too many parallax errors so there can only be a rough estimate which is `10^22` to `10^24`.