Section Links:

History and Genealogy

HISTORY
  Big Bang
  Galaxies etc.
  The Earth
  Continents
  Ice Epochs
  Life
  Precambrian
  Paleozoic
  Mesozoic
  Cenozoic
  First People
  Europeans

GENEALOGY
  Genpics

  Database

LINKS

Galaxies, Stars and Planets

© 1985 by Andrew J. Morris

So the universe had cooled to about 5,000 degrees some 7,000 years after the Big Bang, or 14,999,993,000 years ago. The universe consisted of a hot cloud of hydrogen and helium atoms. These atoms were not perfectly evenly distributed, and as the universe continued to cool, local concentrations of matter began to contract as they were pulled closer together by gravitational forces. Eventually there came to be millions of these local concentrations, separated by vast stretches of void. We call these local areas of concentrated matter galaxies.

Within the galaxies, matter formed into even denser local concentrations. These small concentrations within the galaxies condensed sufficiently to support thermonuclear reactions -- atomic fusion -- and thus the stars were born. Stars go through a life cycle, burning bright while their fuel lasts, then dying out. The lifespan of a star depends on its size, but generally lasts from about a billion to 100's of billions of years. The process is an ongoing one, there are new stars still being born today.

So in our galaxy, which we call the Milky Way Galaxy, there has been sufficient time for almost fifteen generations of the shorter lived stars to come into existence, burn their atomic fuel, and snuff out. One type of massive, short lived star ends its lifespan with an explosive fury that has important consequences for us. When these stars explode, the event is called a super-nova. When a star goes super-nova it becomes so bright that it may give off more light and energy than all the other stars in the galaxy combined. This event lasts for only a few days, but it can have important consequences.

We said earlier that soon after the Big Bang all of the matter in the universe consisted of hydrogen and helium, very simple elements. The normal process of atomic fusion that powers the stars can produce other, more complex elements, but not the full range of elements we find in the world today. Super-novas, on the other hand, produce enough energy to form even the most complex elements found in nature. At the same time, super-novas provide the mechanism to distribute these heavy elements through the galaxy, since as they explode they spew matter out into the surrounding area.

It is also thought that super-novas may actually trigger the formation of other stars. The energy waves coming from these stellar explosions may compress nearby clouds of interstellar gas sufficiently to trigger the condensation that eventually leads to the formation of a new star. Fed by the materials created out of the super-nova, these new stars will have more complex elements than their predecessors. It is probable that just such a chain of events lead to the formation of our solar system, some five billion years ago.

As our solar system formed, it took the shape of a spinning disk of matter with a concentration of material bulging in the center. In fact, it formed a miniture version of the entire galaxy, which is also disk shaped with a bulging center. This is the natural shape for such condensing matter, and can also be seen in the planet Saturn, the rings of which form the remnants of an outer disk.

The large bulge of matter at the center of our solar system condensed to form the sun, while outlying matter condensed into planets at varying distances from the sun. The four inner planets, Mercury, Venus, Earth and Mars, were heated by the sun enough that many of the lighter elements were driven off (in a process similar to evaporation), during the formation of the planets. Thus these inner planets are small, dense, rocky places. On the four outer planets, Jupiter, Saturn, Uranus and Neptune, the gassy elements remain in greater concentrations, so these planets are much larger and less dense than the inner planets. Pluto, the outermost planet, is thought to have once been a moon, perhaps of Jupiter or Saturn, that escaped its original orbit and began instead to orbit the sun.

Visit our Genealogy section to find Larimer County ancestors, or see our Employment department to find a job!