Hello my name is Michael Burton and
welcome to Armagh Astrobytes, the weekly
show from the Armagh Observatory and
planetarium where we bring you stories
about astronomy in bite-sized chunks
today's Astrobyes continues with our
tour of the solar system we return from
the frozen comets of the Oort Opik cloud
at his edge to its fiery center the Sun
our local star. The Sun is by far the
dominant member of our solar system
making up ninety-nine point eight
percent of its entire mass. The Sun is
the bringer of light to our planet, it is
the ultimate source of the energy that
drives the ecosystems that sustain us
from the day/night cycle that forms the
basic rhythm to our life to the seasonal
cycles that drive the light cycles of
biological systems to the climatic zones
that determine what kind of life can
flourish
the Sun is conductor the light on planet
Earth. The Sun is also our local star a
ball of hot hydrogen gas whose engine is
driven by nuclear fusion in its core let
us take a closer look at our local star
this yellow ball that we see in the sky
each day shows us the sun's photosphere
it is where the lights and the Sun
escapes from to then arrived at the
earth eight minutes later it's not a
solid surface but simply the place where
the Sun becomes transparent by reaching
the edge of a bank of fog here the
temperature is about 6000 degrees
where the spectrum peaks in the yellow hence the suns colours, notice
the blemishes on the photosphere
these are sunspots. We now zoom into
one of these sunspots a typical spot is
about the size of the Earth, the central
Umbra looks dark because the
temperature is about 1,500 degrees
cooler than the surrounding photosphere
so emitting relatively less light, strong
magnetic fields are suppressing the flow
of heat from the sun's interior this is
transported in convection cells as can
be seen in the dappled pattern around
the sunspot, the number of sunspots
varies in a 11-year long solar cycle
a minimum few if any spots can be seen. A maximum
many giant spots are seen spread across
the face of the Sun. Above the
photosphere lies the tenuous
chronosphere and then the corona the
sun's atmosphere here we can see solar
flares powerful storms that are the
sounds weather systems driven by flows
of heat and convulsions in the magnetic
field they release huge amounts of
energy in particles the latter stream
out of the solar system as the solar
wind.This is a solar prominence a loop
shape great element of gas extending out
from the photosphere into the solar corona
they can rise to hundreds of thousands
of kilometres above the chronosphere
driven by magnetic forces the white
circle marks the size of the earth see
how small it is in comparison. Prominences are major eruptions in the
Sun and can give rise to coronal mass
ejections where vast numbers of
particles stream out from the Sun at
speeds of hundreds of kilometers per
second they can result in violent space
weather if they encounter the earth
damaging satellites in orbit and even
knocking out power grids. The energy
which creates these Titanic outbursts is produced in the core of the Sun by the
process of nuclear fusion. In the Sun's
core temperatures exceed 15 million
degrees hot enough for hydrogen to be
converted to helium. This process
involves
protons the nuclei of hydrogen atoms
colliding and bonding together to form a
helium nucleus this fusion process takes
place in several steps involving the
temple formation of nuclei like
deuterium along the way before ending up
as helium. The mass of eight helium
nucleus is slightly less than the mass
of the four protons on which it was
formed the difference is converted to
energy the amount given by Einstein's
famous e equals mc-squared formula, it is produced in the form of gamma ray protons
these work their way up to the Sun
surface in a random walk taking tens of
thousands of years to complete while
degrading to lower energies as they do
once the photons reach the photosphere
they can escape this is what we see as a
brightly shining star. Every single
second about four million tons of matter
is converted into energy through nuclear
fusion the Sun has been doing this for
nearly five billion years now and will
continue doing so for as long again this
is a daily light of our Sun our local
nuclear fusion reactor. Thank you
 
you
