On Monday, October 16, 2017 at 2:03:28 PM UTC-6, Gerald Kelleher wrote:
there is another way to express the great event as the birth of a solar system
instead of the demise of a star.

Astronomers, through patient study of many stars out there, have been able to
determine regularities in the luminosity and spectral class of stars, allowing
them to chart what is known as the "Hertzsprung-Russel diagram".

Through this, and many other patient investigations, they have determined that
the birth of a star is a relatively quiet event - as gases in a nebula condense
under gravitational (! that word, again) attraction, leading to two important
things - ignition of fusion reactions, and an increased spin rate (as happens
when a skater pulls in her arms) leading to a disk around the new star from
which planets form.

But the death of a star is violent. Eventually, stars like the Sun burn up all
their hydrogen, from which they have made helium. Helium doesn't undergo a
fusion reaction at the same temperatures and pressures that hydrogen does, so
once the star is no longer heated by hydrogen fusion, it contracts some more.

But helium - and, indeed, all the elements lighter than iron - certainly _can_
yield energy from undergoing a fusion reaction. So after the star has
contracted, eventually it undergoes helium ignition.

If the star is big enough, there will also be carbon ignition and silicon
ignition as subsequent phases.

Of course, you don't believe in gravity, and you don't believe that the rules
about angular momentum apply to celestial objects. I wonder how you explain that
satellites can orbit the Earth just like the Moon orbits the Earth, while the
satellites follow physical laws, but the Moon instead follows celestial laws,
and yet both produce the same result.

John Savard