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Do astronomers know how many galaxies are in the universe?

Answer 1

No,they don't.

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#.

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Answer 2

Luke Allen

Indeed, the number of galaxies in the observable universe is estimated by astronomers to be over 100 billion.

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Answer from HIX Tutor

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.