Download Universe, Earth, and The Solar System Characteristics of Stars

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Characteristics to classify stars include color,
temperature, size, composition, and brightness.
The brightness of a star depends upon both its
size and temperature.
Scientists use light years to measure distances
between stars.
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All stars begin their lives as parts of nebulas,
large clouds of gas and dust spread out in a
large volume.
Gravity pulls the gas and dust together
eventually forming a protostar.
A star is born when the contracting gas and
dust become so dense and hot that nuclear
fusion starts.
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A star is born when nuclear fission starts.
The longevity of a star depends on its mass.
After a star runs out of fuel, it can become a
white dwarf, neutron start, or black hole.
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A white dwarf is only about the size of the
Earth but as much as mass as the sun.
A neutron star is the remains of high-mass
stars.
A black hole is an object with gravity so strong
that not even light can escape. These are
usually formed from the death of the most
massive stars.
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Most stars belong to star systems.
Galaxies can be classified as spiral, elliptical,
and irregular.
Our solar system is the Milky Way Galaxy and
it is a spiral galaxy.
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A spiral galaxy have a bugle in the middle and
arms that spiral outwards.
Elliptical galaxies look round or like flatted
balls.
Irregular galaxies do not have regular shapes.
Obtained from:
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According to the big band theory, the universe
formed instantly in an explosion over a billion
years ago.
Our solar system was formed from a giant
cloud of gas and dust that collapsed.
Astronomers believe the universe will likely
expand forever.
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Our solar system began as a gaseous cloud
called a nebula.
Collapse of nebula formed planetesimals. They
collided and grew larger sticking together to
form planets.
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Most gases escaped the gravity of the planets
that were forming and the inner planets,
Mercury, Venus, Earth, and Mars are relatively
small and rocky.
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Farther from the sun it was much cooler.
Gravity increased in this region and it was able
to capture much of the hydrogen and helium
gas.
This resulted in the outer planets, Jupiter,
Saturn, Uranus, and Neptune.
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Hubble discovered that galaxies are moving
away from us and from each other.
Evidence from this is the doppler effect and
cosmic background radiation. Cosmic
background radiation is the leftover thermal
energy from the big bang.
The doppler effect is red light left over from the
expansion.