MadSci Network: Astronomy

Re: Age of our Solar System verses the age of the universe

Date: Tue Feb 17 14:26:26 1998
Posted By: Dan Berger, Faculty Chemistry/Science, Bluffton College
Area of science: Astronomy
ID: 884580373.As

All the naturally occuring elements we have were created in what must have been a very large star. This star must have accreted from the far flung dust of creation (just H atoms?), organized,evolved and shifted through several stages before blowing up to disperse the material to make our sun (which must also be mostly heavier elements?). All this gathering, fusing, dispersing must have taken a very long time. Our sun is estimated to be 5 billion years and yet, assuming we are the very first generation with planets, the universe is thought to be only 15 billions or so. This does not seem to be enough time. What is the estimate of time for a star to accrete from nebula?

There was never too much problem with the idea of the age of the universe vs. the age of the solar system. The scenario as I have always understood it is this:

So picture this: a few million years to form a big star from a cloud of primordial hydrogen and helium; then a lifetime of not more than a few million years, followed by a violent explosion which synthesizes all the elements up through who-knows-what -- at least to uranium, probably further. Finally, another few million years to reform and condense into our solar system, which has an age of some 4.5 billion years.

Total time elapsed: less than a billion year, only a small fraction of the estimated age of the universe.

Actually, the problem has recently gotten worse and better at the same time. From the latest deep-field surveys, it looks very much like galaxies were forming quite a lot earlier (maybe less than a billion years after the Big Bang!) than anyone believed just ten years ago. So it looks like second- or even third-generation star-processed material was available much earlier than previously supposed. On the other hand, this does tend to play heck with theories of cosmic evolution... as usual, the theorists are being sent back to the ol' drawing board!

For more information about the latest estimates of the age of the universe and the ages of the oldest galaxies, check out back issues of scientific newsmagazines such as Science News, in your library. One such article is in Science, 23 January 1998, p. 479; it refers to another Science item, 4 April 1997, p. 36.

A caution: like most new and important information, these data which say that galaxies were forming so long ago have not yet been fully accepted by astronomers.

By the way, the Sun is not mostly heavy elements. The Sun is overwhelmingly made of hydrogen and helium in a ratio of about 4:1; the rest of the elements are no more than 1% of the total. The rest of the solar system is somewhat depleted in the light elements because most planets don't have enough gravity to hold 'em, but Jupiter and Saturn have elemental abundances estimated to be the same as those in the Sun.

You can find more information here:

  Dan Berger
  Bluffton College

Current Queue | Current Queue for Astronomy | Astronomy archives

Try the links in the MadSci Library for more information on Astronomy.

MadSci Home | Information | Search | Random Knowledge Generator | MadSci Archives | Mad Library | MAD Labs | MAD FAQs | Ask a ? | Join Us! | Help Support MadSci

MadSci Network,
© 1995-1998. All rights reserved.