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How do astronomers know our universe is expanding?

Answer 1

In the 1930s, Edwin Hubble, an astronomer, detected hundreds of galaxies besides our own and some were very distant. He found that the light that reached Earth was mostly in the red part of the section. Thus, the REDSHIFT was discovered

When Hubble noticed that these galaxies were moving away from Earth and that their light was in the red part of the spectrum, he put forth the theory that the universe was expanding, which has since been shown to be true. The farther an object is from Earth, the more redshift its light will be.

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Answer 2

Hailey Alexander

The main way that astronomers determine that the universe is expanding is by observing far-off galaxies. They do this by measuring the redshift of the light from these galaxies, which shows that they are moving away from us. They also gather evidence for the expansion of the universe by observing the cosmic microwave background radiation.

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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.