The Sun
•Characteristics
•How it compares to other
stars
•How we have studied it
•It’s evolution history
•It’s projected future
Characteristics
The sun is actually a medium sized star. it only appears
larger because it is so close to the earth.
The distance from earth to the sun varies
from91,377,000 miles to 94,537,000 miles.
Its diameter is approximately 865,400 miles.
The suns average density is 1.41.
It has a temperature of about 10 to 20 million degrees
Celsius & a pressure of I billion atmospheres.
Properties of the Sun


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The suns volume can hold over one
million earths.
A particle traveling at the speed of
light takes 8 minutes and 20
seconds to travel between the sun
and earth.
Its mass is 745 times greater than all
the planets together.
The suns interior temperature is as
high as 15,000,000 degrees Celsius.
How the Sun Compares to
Other Stars
sun
star
How the Sun Compares to Stars…

The smallest stars can be smaller
than the earth, but the largest stars
can be over 2,000 times the diameter
of the sun.

The sun’s temperature is about
5,500 degrees Celsius. Stars that are
blue, have a temperature of
approximately 30,00 degrees
Celsius. Red stars’ temperatures are
How the Sun Compares to
Stars…
Betelgeuse is one tenmillionth as dense as the sun
Betelgeuse is red, the sun is
yellow, and Sirius is blue.
Blue is hotter in temperature
and red is cooler.
How the Sun has been Studied
Early Chinese astronomers studied the sun while it was red
and dim during sunset and sunrise.
Galileo studied the sun with a telescope and his eyes, which
in his later years caused him to become blind.
In 1859, astronomers used a spectroscope and were able to
prove that lines in the suns spectra were connected to
specific chemical elements.
How the sun has been studied
A solar telescope had been designed to view
the sun in a safer way. It projects a large
image of the sun into a dark room
underground. With special glasses,
astronomers can observe the sun and its
changes.
Satellites are used to observe the sun without
interfering with the Earth.
The suns evolution history
The sun’s evolution history

Started with an advancing contraction of gas by self-gravitation, which
sometimes can be interrupted by thermonuclear burning. After certain
types of nuclear fuel (hydrogen, helium) are exhausted, the
contraction-burning cycle will start over with higher temperatures. The
sun’s evolution stages are from primitive solar nebula contraction to
the black dwarf stage. The sun spent a major part of it’s life in the
main sequence. Then it went to the movement of the black-dwarf
evolution stage, which is the final stage in it’s evolution.
The suns projected future

The sun is said to last for about another 5
billion years.
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In about 250 million years the sun will
grow 100 times larger and 500 times
more luminous.
The sun’s projected future
•Eventually, the suns hydrogen resources with be used
up.
•The fusion energy will no longer inflate the sun.
•Gravity will compress the sun’s core.
•After the fusion reaction has changed the hydrogen to
helium, the pressure will then start nuclear reaction of
helium.
•Now, the sun will change into a red giant.
•The sun will only remain a red giant for
approximately 700 million years.
•Finally, the interior of the sun will contract into a
white dwarf about the size of earth and then cool down
to a black dwarf. This will be the end of the sun.
Interactive websites

click here to see the how the sun and other stars
evolve

click here to watch the animation of the sun
within the last 48 hours