View Full Version : How long did the Sun take to form?
07-22-2009, 05:30 PM
From whatever nebula our solar system was formed from, how long did it take the gasses therein to form the sun? Also, how long did it take to form the Earth? I realize that it is constantly acquiring mass, but was there a period where it picked up most of its bulk?
07-22-2009, 10:04 PM
Not sure where you start counting from.
If the sun is 4.5 billion years old and the age of the universe is 13.5 billion years old then it took 9 billion years to form.
Ok, not fair you might say and I agree.
However, there were a few stars prior to our sun forming that were born, lived then blew up to provide the stuff for our sun.
So, do you count from when the last star (or several stars) blew up and produced the gas cloud our sun formed out of till our sun initiated fusion?
Not sure anyone can know that. Could depend on so many things (density of the original cloud our sun formed from which would depend on what created it in the first place as well as other gravitational effects and so on).
I certainly could be wrong but I think this is unknowable.
07-23-2009, 09:36 AM
Well, I said our Sun, but I just want to know what kind of time scale we are talking about to go from dust cloud to star.
07-23-2009, 09:58 AM
According to this:
"Over about 100,000 years, the competing forces of gravity, gas pressure, magnetic fields, and rotation caused the contracting nebula to ... form a hot, dense protostar (a star in which hydrogen fusion has not yet begun) at the centre."
"Within 50 million years, the temperature and pressure at the core of the Sun became so great that its hydrogen began to fuse"
So 100,000 years to become a star, 50 million to become a star as it is now.
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