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How do scientists estimate the number of galaxies in the universe?

Answer 1

We have counted them using optical ground-based and space telescopes. However we will never know how many galaxies there are outside of the observable universe.

Using telescopes such as the Hubble space telescope we have seen the most distant of galaxies scraping the edge of the light horizon. The light horizon is the where beyond it light has not has reached us,

Scientists also use the density of the universe to estimate the amount of galaxies in our observable universe.

Right now scientists estimate that there are #200# billion galaxies in the observable universe. However we may never know how many galaxies in the universe, because light from the galaxies have not reached us yet and may never will due to the rapid expansion of the universe.

I hope that helps!

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Answer 2

Claire Anctil

By using telescopes like the Hubble Space Telescope to conduct sky surveys and analyze the distribution of galaxies across different regions, scientists are able to estimate the total number of galaxies in the observable universe by counting the number of galaxies within a small portion of the sky and extrapolating 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.