After the Big Bang occured ,how long did it take for the first planets to appear?

It took something like 300,000 years for the universe to cool down to the point where hot plasma could condense into neutral matter, forming atoms of mostly hydrogen & some helium -- and essentially no other elements. This gas began clumping under the influence of gravitation, producing the first generation of stars. These early stars would NOT have had planets due to the lack of other elements in the disks of gas from which they formed.

It would take the lifetime of these first stars -- at least several hundred thousand more years -- to forge elements heavier than helium, which takes place near the end of their lifetimes. The largest such stars (with the shortest lifetimes) would end their existence in cataclysmic supernova explosions, which spewed heavier elements into the interstellar medium.

It was THIS material, in a whole new cycle of star formation, that would condense into an accretion disk and eventually stars possibly bearing planets. So it would have been at least a billion or so years after the big bang before the first planets formed.

Our own solar system (including good ol' terra firma) didn't form until some 10 billion years after the big bang, from remnants of earlier supernovae. As Carl Sagan liked to say, we are literally made of star stuff.

Your answer is correct Prof. I must admit that I made a little mistake on this question.
But it turned out ok. It should have read:

After the Big Bang occured ,how long did it take for the first stars to appear?


How Old Is the Universe?

Hubble observations allowed astronomers to calculate a precise age of the universe using two independent methods. The findings reduced the uncertainty to 10 percent. The first method relied on determining the expansion rate of the universe, a value called the Hubble constant, to calculate the age. In May 1999 a team of astronomers obtained a value for the Hubble constant by measuring the distances to 18 galaxies, some as far as 65 million light-years from Earth. By obtaining a value for the Hubble constant, the team then determined that the universe is 12 to 14 billion years old.

"In the second method astronomers obtained an age by measuring the light from old, dim, burned out stars, called white dwarfs. The ancient white dwarf stars, as seen by Hubble, turn out to be 12 to 13 billion years old. Because earlier Hubble observations showed that the first stars formed less than 1 billion years after the universe's birth in the big bang, finding the oldest stars put astronomers well within arm's reach of calculating the absolute age of the universe."


Source

omg -- I didn't realize this was a trivia question or I would have been more careful to check facts before spouting off.

These new Hubble observations confirm and refine what was already known with some accuracy. After all, the basic info had already been digested into magazine articles that were read by me!

Nothing wrong with your answer, Prof, or the always-wanted additional information.