Why did it take so long for the existence of other galaxies to be established?

n the early 1900s, astronomers were debating the makeup of spiral nebulae — cloudy, spiral-shaped objects found throughout the night sky. Were they gas clouds located within our Milky Way galaxy, or were they vast groups of stars located far beyond our galaxy?

In 1919, American astronomer Edwin Hubble tackled the question. His keen astronomical knowledge was combined with a powerful tool – the Hokr telescope with its 100-inch mirror, on top of Mount Wilson in California. Hubble used the telescope’s resolution and light-gathering power to take a series of photographs of the great nebula in Andromeda. For the first time, the images revealed faint stars in the nebula.

Hubble now knew the Andromeda nebula was a collection of stars, but how far away was it? To find out, he used a known method for calculating distance based on very bright variable stars.

explanation:

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