Download Section 14.7: The Sun

Section 14.7 The Sun: An Important Star
 A star like the ones we see “twinkling” at night, but its
closeness to Earth makes it look much bigger and brighter,
and we can even feel heat coming from it
 So bright that you can’t see other stars until the sun has set
 Provides energy needed by all plants and animals
 Its gravitational pull keeps us in our steady orbit
 1.4 million km across (the earth is only 13000 km across)
 To compare sizes, if the Sun is a basketball, the Earth
would be the head of a pin
Where does the Sun’s energy come from?
• Sun produces energy through Nuclear Fusion
• Nuclear Fusion: A process during which substances fuse to
form new substances, releasing huge amounts of heat, light, and
other forms of energy
• The pressure and temperature inside the Sun are so high that
hydrogen nuclei fuse to form helium nuclei.
• Scientists estimate the sun will continue to produce energy for
another 5 billion years before it runs out of fuel.
Parts of the Sun:
Corona: The hot outer par of the sun where the gases reach
temperatures of about 1 million degrees Celsius.
Chromosphere: The inner atmosphere
Photosphere: The surface of the sun made of churning gases
(not a solid surface); average temp is about 5500 degrees Celsius
Solar Flare: A sudden eruption of hydrogen gas on the surface of
the sun, usually associated with sunspots and accompanied by a
burst of ultraviolet radiation that is often followed by a
magnetic disturbance.
Core: Where nuclear fusion produces the Sun’s energy (15
million degrees Celsius)