TEKS 8.8A describe components of the universe including stars, nebulae and galaxies, and use models such as the Herztsprung-Russell diagram for classification
TEKS 8.8B recognize that the Sun is a medium-sized star near the edge of a disc-shaped galaxy of stars and that the Sun is many thousands of times closer to the Earth than any other star
We live in a galaxy called the Milky Way. A galaxy is a system of stars, planets gas, dust and dark matter.
Within galaxies are star forming regions called nebula. A nebula is a
cloud of dust, hydrogen and helium gases.
It is in these clouds of gas and dust that
stars sometimes form.
A star is a large ball of gases that generates
its own energy through nuclear fusion.
Fusion is a process in
which hydrogen
and helium fuse to form
heavier elements.
This process generates
large quantities of
energy.
The energy is emitted from the
star in the form of heat
and light.
Stars undergo
many changes through
their evolution.
Depending on the mass of the star, its lifetime may be a few million years to trillions of
years. Lower massed stars can generate
energy for billions of years.
Stars that are very massive generate
energy for only a few million years.
Nebula with protostars
Stellar Evolution
Over the course of the star’s evolution
the energy generated by the star begins to decrease.
Ultimately, the star will
no longer have
enough hydrogen
or helium to continue to
radiate.
Our Sun is only one of many stars in the
universe.
It is considered to
be a medium-sized star near the
edge of our disc-shaped
galaxy.
So what will happen to our Sun?
At the end of the
sun’s life, it will
gradually brighten, as it has
been doing for the last
4 billion years.
Around 5,000,000,
000 AD, the
hydrogen in the
Sun’s core will run
out.
The sun will
expand into a red
giant about three times larger
than it is now.
The increased brightness will boil the oceans and raise our temperatures to over 1000 Kelvin.
Eventually, the Sun will shrink, but
then expand again,
charring the surface of the earth with solar prominences.