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Why was the parsec invented?

Answer 1

AU is defined as Earth-Sun average distance. On the contrast, Parsec is more general, relating parallax with AU. 1 parsec is the radius of a circle with 1 AU arc subtending 1" at the center.

The conversion from parsec to light year units is 1 parsec = 206264.8 AU, or nearly 3.28 light years.

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Answer 2

Asher Cohen

A convenient way to express the vast distances between stars and galaxies in the universe is to use the parsec, which was created as a unit of measurement for astronomical distances beyond the solar system. It is defined as the distance at which one astronomical unit subtends an angle of one arcsecond.

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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.