How long is a sun lifespan?

Question

How long is a sun lifespan?

Answer 1

A star like our own lasts for about 10 billion years!

Answer 2

When you say "A Sun", i'm assuming you're talking about our sun, Sol, which is the G2V class star at the center of our solar system.

And lifespan would depend on at which phase of our sun's life you would consider the star "dead".

If you consider the sun "dead" when it begins to expand and renders earth uninhabitable when our atmosphere and oceans boil off into space, that would be in about 3-4 billion years from now, or 7-8 billion years old.

If you consider the Red Giant phase to be "dead", when the sun grows large enough to mercury, venus, and maybe earth, then that will be in 5-6 billion years from now, or about 10 billion years old.

If you consider the "White Dwarf" phase dead, when the sun is no longer burning fuel but cooling off from when it was burning it's fuel, and about the size of the earth, that would be in about 7-8 billion years, or around 11-12 billion years old.

If you consider the final phase, a "Black Dwarf" to be dead, when the sun finally cools to a temperature of 5 degrees Kelvin, that will be in about 1,000 trillion years from now (10^15 years).

It's a really long time :)

Answer 3

Untill tomorrow

Answer 4

A "main sequence" star will vary in lifespan based on it's mass.  

http://outreach.atnf.csiro.au/education/...

If you are referring specifically to our sun, however, it should reach red giant phase somewhere in the vicinity of 5 billion years from now, in which case, the sun will still be alive, but it wil "swell" so large, that it will encompass the earths orbit.  Not to worry, though, living conditions should be obliterated a while before that due to a loss of atmosphere in the stages just prior to that.

Answer 5

  About 10 billion years.