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What would happen if the sun was half its size? What would happen if it was double its size?

Answer 1

That depends on its mass.

Before our sun shrinks to less than half its current size, it will double in size in another 3–4 billion years, making life on Earth impossible in each scenario.

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Answer 2

Levi Acosta

If the Sun was half or double its mass it would still be a star but a different type.

Our Sun is a G class star with a surface temperature of about #6,000^@K#.

If the Sun had half of its mass it would be a K class star with a surface temperature of about #4,000^@K#. It would be considerably less bright having a luminosity of maybe #10%# of that of the Sun. The Earth would need to be closer to the Sun to receive the same amount of solar radiation.

If the Sun had double its mass it would be an A class star with a surface temperature of about #10,000^@K#. It would be considerably brighter having a luminosity over 20 times that of the Sun. The Earth would need to be further away to receive the same amount of solar radiation.

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Answer 3

Levi Alexander

Half the size of the Sun would make it a smaller, colder star, producing less energy and lowering Earth's temperature; twice the size of the Sun would make it a larger, hotter star, possibly raising Earth's temperature and changing its habitability.

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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.