The source of life
Without the sun, there could be no life on earth.
Energy pours up out of the raging hot atomic furnace that is the center
of the sun. It moves up to the sun’s seething, boiling surface and
rushes out into space as waves of light.
The waves of sunlight spread out in all directions. They travel at the
tremendous speed of 186,282 miles (299,792 kilometers) per second. Most
of them speed on into the endless darkness of space. But some head
straight toward a small, bluish planet that lies in their path. It is
earth.
The waves of sunlight pass through earth’s atmosphere and travel down to
the planet’s surface.
There, the light waves strike the leaves of green plants—trees,
bushes, and blades of grass.
Green leaves are made of millions of tiny cells, like little bags. In
each cell there are little blobs of green stuff called chlorophyll. When
sunlight passes into a leaf, the little blobs of chlorophyll catch and
hold tiny bits of the light—sparks of the sun’s energy.
Plant cells are like factories, where the plant’s food is made. Using
the captured sunlight for power, the green blobs of chlorophyll turn
water and carbon dioxide gas into a kind of sugar. This sugar is stored-
up energy. The plant uses the stored-up energy for the
power to grow. Without energy from the sun, the plant couldn’t grow or
live.
A steer moves slowly through a field of grass. Each plant it eats has
some of the stored-up energy. The energy is taken in by the steer’s body
and used for the power to make the steer live and move. Without the
stored-up energy it gets from the plants it eats, the steer could not
stay alive.
The steer is part of a herd being fattened for market. In time, the
steers’ bodies will be turned into steaks,
roasts, and hamburgers for people to eat. The energy in the steers’
bodies will go into peoples’ bodies, where it will be used to keep them
alive. And, of course, people also eat many kinds of plants for the
energy that’s in them.
All living things must take in energy in order to stay alive. And nearly
all energy comes from the sun. So the sun gives us much more than just
light and heat. It truly gives us life.
