"The Sun is a huge, glowing ball at the center
of our solar system. The sun provides light,
heat, and other energy to Earth. The sun is made
up entirely of gas. Most of it is a type of gas
that is sensitive to magnetism. This sensitivity
makes this type of gas so special that
scientists sometimes give it a special name:
plasma. Nine planets and their moons, tens of
thousands of asteroids, and trillions of comets
revolve around the sun. The sun and all these
objects are in the solar system. Earth travels
around the sun at an average distance of about
92,960,000 miles (149,600,000 kilometers) from
it.
The sun's radius (distance from its center to
its surface) is about 432,000 miles (695,500
kilometers), approximately 109 times Earth's
radius. The following example may help you
picture the relative sizes of the sun and Earth
and the distance between them: Suppose the
radius of Earth were the width of an ordinary
paper clip. The radius of the sun would be
roughly the height of a desk, and the sun would
be about 100 paces from Earth.
The part of the sun that we see has a
temperature of about 5500 degrees C (10,000
degrees F). Astronomers measure star
temperatures in a metric unit called the Kelvin
(abbreviated K). One Kelvin equals exactly 1
Celsius degree (1.8 Fahrenheit degree), but the
Kelvin and Celsius scales begin at different
points. The Kelvin scale starts at absolute
zero, which is -273.15 degrees C (- 459.67
degrees F). Thus, the temperature of the solar
surface is about 5800 K. Temperatures in the
sun's core reach over 15 million K." -
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