A
summary of the physical and chemical nature of life must begin, not on
the Earth, but in the Sun; in fact, at the Sun's very center. It is here
that is to be found the source of the energy that the Sun constantly
pours out into space as light and heat. This energy is liberated at the
center of the Sun as billions upon billions of nuclei of hydrogen
atoms
collide with each other and fuse together to form nuclei of helium, and
in doing so, release some of the energy that is stored in the nuclei of
atoms. The output of light and heat of the Sun requires that some 600
million tons of hydrogen be converted into helium in the Sun every
second. This the Sun has been doing for several thousands of millions of
years. The nuclear energy is released at the Sun's center as
high-energy gamma radiation, a form of electromagnetic radiation like
light and radio waves, only of very much shorter wavelength. This gamma
radiation is absorbed by atoms inside the Sun to be reemitted at
slightly longer wavelengths. This radiation, in its turn is absorbed and
reemitted. As the energy filters through the layers of the solar
interior, it passes through the X-ray part of the spectrum eventually
becoming light. At this stage, it has reached what we call the solar
surface, and can escape into space without being absorbed further by
solar atoms. A very small fraction of the Sun's light and heat is
emitted in such directions that after passing unhindered through
interplanetary space, it hits the Earth
No comments:
Post a Comment