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The diagram above shows a
cross-section of our Sun. Beginning deep in the centre, the
core, we find a very high temperature indeed. You may think
it's hot outside sometimes with the Sun blazing down from
the clear blue sky. For the British Isles, we find anything
above 30 degrees (or so) Centigrade almost unbearable. I don't
think we would survive the Sun's core then, with temperatures
around 15 million °C! Here, under intense pressure and heat,
the hydrogen gas is forced together to make another gas, helium.
This process produces a small (but very important) amount
of energy - including heat and light. The Sun loses 4 million
tonnes of mass every second in this conversion, but still
has enough fuel to continue happily shining away for about
5,000 million more years.
Meanwhile, back in the core...
all this heat and stuff is trying to get out of the Sun, first
through the RADIATION zone - a solidy type of area made of
compressed gas. Next it finds the CONVECTION zone, where currents
of hot gas are constantly rising, as they are heated from
below, and falling as they let out the heat and energy out
into space.
The bright visible bit of
the Sun we see is called the PHOTOSPHERE. The temperature
here is just under 6000 degrees Centigrade. Then the energy
flies though the atmosphere, zooming through the CHROMOSPHERE
and, further out, the CORONA, the tenuous atmosphere of the
Sun only visible during a Total Solar
Eclipse.
Because the Sun is a big ball
of gas it actually rotates at different speeds. The equator
rotates faster at 25 days, while the poles are slowest at
about 35 days.
 At
times, on the bright photosphere, darker lower temperature
patches called Sunspots can appear. Their position and number
change with the rotating Sun and with the eleven year Solar
Cycle. At the start of each cycle spots appear at the higher
latitudes (near the poles) but as the cycle moves on newer
spots are seen slowly working their way towards the equator.
The number of spots on the Sun increases over this time as
well. This Solar Cycle is all to do with the action of magnetic
fields as they weave, warp and smash their way through the
Sun. Sunspots can appear on their own, but more commonly appear
in pairs and in groups lasting anything from a few days to
a few weeks. As for observing these sunspots, please remember
the Sun is very dangerous. You can feel the heat and see its
brightness on a sunny day, just imagine how this is strengthened
through a telescope or binoculars:
NEVER LOOK AT THE SUN DIRECTLY
THROUGH ANY OPTICAL INSTRUMENT - THE FOCUSED HEAT AND LIGHT
WILL DAMAGE YOUR EYES PERMANENTLY
The safest way to look at
the Sun is to project the Sun's image down the telescope onto
a piece of card. You can line up the telescope approximately
by watching the telescope's shadow on the ground. When the
shadow is at its smallest, the Sun's image will be coming
down the scope - although you may need to 'wobble' the scope
a little to get the perfect position. Where your eyes would
have been you place a piece of white card. The further the
card from the eyepiece the larger the image, of course. After
focusing, you and all your excited friends can see the sunspots,
plus this makes it very easy to draw any sunspots.
Some cheaper telescopes are
supplied with sun filters that fit onto the eyepiece. Throw
these away immediately, they are very dangerous because they
take the full focused power of the Sun and could shatter.
DO NOT USE EYEPIECE SUN FILTERS.
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 The
temperature at the centre of the Sun is around 15 million
degrees Centigrade.
The
Sun is losing 4 million tonnes of mass every second.
One
square centimetre of the Sun's surface shines with the brightness
of 60,000 candles.
The
Sun's diameter is 109 times that of the Earth.
It
would take you over 2,100 years if you wanted to walk to the
Sun.
 What
do you call someone who is born on our Sun?
How to safely
Observe the Sun
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