Her a question for all you brain children ?

Question

would there be life on earth if our star was twice the size it is now; and where would be the sweet spot for life be

Answer 1

It really doesn't matter what size the Sun is, only how bright it is. Assuming twice the size means twice as bright, Earth would be too hot. Then the sweet spot would be about where Mars is now, because light obeys the inverse square law, twice as bright means you need to be the square root of 2, or about 1.4 times as far away to get the same amount of light on your planet, and 1.4 times Earth's distance is pretty close to Mars.

Answer 2

No, the earth would be too hot -- and the star's lifetime would probably be too short to allow life to develop anywhere.

Answer 3

Twice the size meaning twice the surface area, twice the mass, twice the diameter?

Assuming you meant twice the diameter, that would mean that the Sun would have four times the surface area and therefore generating 4 times as much light and heat. That would mean that the Earth would have to be about four times farther away from the Sun. However, because the sunlight would have more time to spread out and cool down before reaching the Earth, it would not receive as much heat per square mile.

Doing a quick calculation, the optimum distance would probably be about 3.5 times our current distance of approximately 93 million miles or about 325.5 million miles.