does it simply mean that the distance between objects in the universe is expanding, while the size of the objects remains the same, or would the objects in the universe increase in size at the same rate at which the distance between such objects expands?

and also if the former is true, at some point wouldn't the distance between for example, the earth and our sun, increase to such a distance at which the earth would no longer be inhabitable due to the decrease in temperature?

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