2
votes
2answers
98 views

Is the Sun homogeneous?

Does the Sun have the same composition and density everywhee within it? How does it vary in other stars?
4
votes
1answer
105 views

How often do stars pass close (~1ly) to the Sun?

Interstellar exchange of massive objects is difficult across several light years. But as the stars orbit the galaxy the distances between them change. I don't find data for neighbor star distances ...
4
votes
1answer
86 views

Cooling of stars

If all stars suddenly stopped producing heat (or heating up) which stars would cool to absolute zero first and how long would it take?
3
votes
3answers
123 views

Does the Sun have hard radiation?

Does the Sun spread hard radiation waves around the Solar System? If so, why are we safe here (or are we even safe)?
5
votes
1answer
150 views

If we were to see the Sun with our naked eyes from the Orion belt, would all planets be encompassed inside the star? Is this calculable?

When we see a star it looks much bigger in diameter to us than it really is, this picture (extracted from here) explains what I mean: Notice that the point we see in the skynight, represented by ...
6
votes
1answer
58 views

How do large solar flares compare to flares on other stars?

Solar are violent releases of solar magnetic energy. Other stars are also known to have magnetic fields, in some cases much stronger than the Sun. How do the largest stellar flares compare to the ...