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How do astronomers estimate how many galaxies are in the universe?

Answer 1

They typically count the galaxies in a very small region of the sky and extrapolate.

Other methods include multiplying up and estimating the mass in a cluster of galaxies based on their gravitational effects.

It is important to remember that, just a century ago, astronomers believed the Milky Way to be the entirety of the universe. This is a very young science, and as such, it is an extremely exciting field to study. The point is that nobody can possibly count all the galaxies; all figures are estimates that improve on previous values.

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Answer 2

Nova Adams

To get an estimate of the total number of galaxies in the observable universe, astronomers count the galaxies within a representative region of the sky using statistical techniques, and then extrapolate this count to the entire universe.

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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.