Made this when I was 12 for my group's report about astronomy. A presentation about Astronomy--Stars, Galaxies, Constellations, etc. I don't really see the point in just keeping it unused in my computer...
Beyond the SolarBeyond the Solar
By: Group 2By: Group 2
Astronomy is the study of the night sky-
from planets and moons to the stars and
galaxies. Shortly, astronomy is the study
of space and heavenly bodies.
Astronomy is the most ancient of all
sciences, dating back tens of thousands of
years. It came from the Greek words astro
meaning ‘star’ and nomia meaning law.
Astronomers are the people who engage
in astronomy. They use telescopes to
study objects far fainter and smaller that
cannot be seen with the naked eye.
Most astronomers work in observatories
far from city lights, where they can get a
very clear view of the sky.
Telescope and ObservatoryTelescope and Observatory
Billions of nebulae or external galaxies
make up the universe, which is believed to
be an infinitely old and large super
system. Galaxies are giant groups of
millions or even trillions of stars. Our own
galaxy is the Milky Way. There may be 20
trillion galaxies in the universe.
Only three galaxies are visible to the
naked eye from the Earth besides the
Milky Way – the Large and Small
Magellanic Clouds, and the Andromeda
Although galaxies are vast, they are so far
away that they look like fuzzy clouds. Only
in 1916 did astronomers realize that they
are huge star groups.
Classification of GalaxiesClassification of Galaxies
As classified by astronomer Edwin
Hubble, there are three basic types of
galaxies- spiral, barred spiral, and
elliptical. Another type, which is
considered rare, is the irregular galaxy.
Spiral GalaxySpiral Galaxy
• A spiral galaxy consists of a dense core at
the center surrounded by a flat disk, a
corona, and curved, spiraling arms. It
includes both old and young stars. Spiral
galaxies range in diameter from 20,000 to
more than 100,000 light-years. About 80%
of galaxies are of the spiral type.
Barred Spiral GalaxyBarred Spiral Galaxy
• A barred spiral galaxy consists of a long
bar of individual stars that passes through
the central region of the galaxy. Spiral
arms appear to extend from the ends of
the bar. Barred spiral galaxies are named
based on their general appearance.
Elliptical GalaxyElliptical Galaxy
• An elliptical galaxy is vast and very old, it
is the most common of all galaxies. It is
egg-shaped and has a smooth and round
appearance. It is made up of as many as
a trillion stars, therefore it has great mass.
Irregular GalaxyIrregular Galaxy
Irregular galaxies are galaxies with no
obvious shape. They may have been
formed from the debris of galaxies that
crashed into each other. It is full of young
• Stars are huge balls of hydrogen and
helium gas. It appears only like a tiny dot
in the sky because of its great distance
from the Earth. Stars twinkle because the
air above the Earth’s surface is always in
motion and the layers of the atmosphere
have different densities.
Properties of StarsProperties of Stars
Stars vary in brightness depending on
their size, temperature, and distance from
Color and Temperature
• The color of a star depends on its size and
temperature. Young stars are blue white
or white in color. They have extremely
high temperature. Old stars are red in
color and have low surface temperature.
The sun is a yellow star and has moderate
surface temperature compared to blue
white or white and red stars.
Temperature of Stars According to ColorTemperature of Stars According to Color
White and Blue White 30, 000 to 60,000 F
Yellow 10’000 F
Orange 6,000 to 8,000 F
Red 3,000 to 6,000 F
• The size and brightness of a star
depends on its mass – that is, how much
gas is made of.
Stars vary in size. A star may be a super
giant, a giant, or a dwarf.
• The average distance between the Earth
and the sun is about 150 million
kilometers. The value is equivalent to one
astronomical unit (AU). Another unit that
can be used to express distances in outer
space is the light-year. This is the distance
traveled by light ate the speed of 300,000
kilometers per second in one year. One
light year is equivalent to about 9.6 million
• The measure of a star’s brightness is
called magnitude. The brightest stars are
classified as first-magnitude stars. Stars
beyond the sixth magnitude can only be
seen with a telescope.
Some stars undergo regular periods or
phases of brightness and dimness. Such
stars are called variables. They expand
and contract, causing their light to pulsate.
Evolution of StarsEvolution of Stars
• Stars evolve from the hydrogen gases
found in interstellar mediums called
nebulae. Through the process of
contraction, the temperature rises
sufficiently to transform hydrogen gas
present in the mass of to helium. The hot
ball begins to glow brightly and gives rise
to a protostar.
Equilibrium in StarsEquilibrium in Stars
• The sun and majority of stars are in a
state of equilibrium. There is a mutual
gravitational attraction between the
masses of forces that tend to collapse the
star towards the core. The gravitational
force must be in equilibrium with its
internal force as shown by the fact that
stars, like the sun, have remained more or
less the same for billions of years.
• Hundreds or thousands of associated
stars are called star clusters. Star clusters
that are arranged in a definite pattern form
a constellation. Earth’s revolution around
the sun enables people to see different
constellations in the sky at different times
of the year. Constellations such as Ursa
Minor, Ursa Major, Draco and Cassiopeia
are always visible around the North Star.
The North StarThe North Star
• The North Star, also known as Polaris, is
located above the North Pole. It was first
noticed by William Herschel in 1780. As
seen through the Hubble Space
Telescope, it lies in the handle of Ursa
Minor. Travelers usually make Polaris as
their guiding star as it helps them in
determining direction. It is very close to
North Celestial Pole, making it a North
• You will notice that constellation are
usually named after mythical gods,
legendary heroes, and animals. These
names were given to the star patterns,
because their arrangements in the sky
outline the shapes of animals, heroes and
• A constellarium is a device that projects
the outlines of the constellations on
surfaces, such as ceilings and walls.