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Sun,
closest star to Earth. The Sun is a huge mass of hot,
glowing gas. The strong gravitational pull of the Sun
holds Earth and the other planets in the solar system in
orbit. The Sun’s light and heat influence all of the
objects in the solar system and allow life to exist on
Earth.
The Sun is an average
star—its size, age, and temperature fall in about the
middle of the ranges of these properties for all stars
. Astronomers believe
that the Sun is about 4.6 billion years old and will keep
shining for about another 7 billion years.
For humans, the Sun is
beautiful and useful, but also powerful and dangerous. As
Earth turns, the Sun rises over the eastern horizon in the
morning, passes across the sky during the day, and sets in
the west in the evening. This movement of the Sun across
the sky marks the passage of time during the day. The
Sun’s movement can produce spectacular sunrises and
sunsets under the right atmospheric conditions. At night,
reflected sunlight makes the Moon
and planets bright in the night sky.
The
Sun provides Earth with vast amounts of energy every day.
The oceans and seas store this energy and help keep the
temperature of Earth at a level that allows a wide variety
of life to exist. Plants use the Sun’s energy to make
food, and plants provide food for other organisms. The
Sun’s energy also creates wind in Earth’s atmosphere.
This wind can be harnessed and used to produce power.
This
information has brought it to you from Encarta 2002
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