3. Universe
• defined as everything that exists,
everything that has exists and everything
that will exists.
• Includes planets, moons, minor planets,
stars, galaxies, the content of intergalactic
space, and all matter and energy.
4. SIZE OF THE UNVERSE
• The Universe is large in size and consists of billions
of galaxies, which in turn consist of billions of
stars.
Physical size of Universe
• The size of the Universe is immense. It is
estimated that the Universe is 156 billion
(156,000,000,000) light years across. Since light
travels at approximately 299,800 kilometers per
second or 186,000 miles per second, you can see
that the distance is very large.
5. Number of galaxies and stars
The Universe consists of
approximately 100 billion
galaxies. Each galaxy consists of
anywhere from 10 million to 1
trillion (1,000,000,000,000) stars
rotating around a center area.
Each star in a galaxy is a sun,
similar to our Sun. Some stars are
much larger than our Sun, while
others are smaller.
6. Our galaxy
Our Sun, the Earth and
planets in our Solar System
are part of the Milky Way
galaxy. It is called that
because, on a clear night, the
many stars in our galaxy
almost look like milk spread
across the sky.
7. Doppler Effect
• an increase (or decrease) in the frequency
of sound, light, or other waves as the
source and observer move toward (or
away from) each other.
• named after the Austrian physicist Christian
Dopple
8. An approaching source moves closer during period of the sound
wave so the effective wavelength is shortened, giving a higher pitch
since the velocity of the wave is unchanged. Similarly the pitch of a
receding sound source will be lowered.
9. The Doppler Effect
In Astronomy
In astronomy, the Doppler effect
was originally studied in the
visible part of the electromagnetic
spectrum.
• Inverse relationship of
frequency and
wavelength,we can describe
the Doppler shift in terms of
wavelength.
10. Astronomers use Doppler shifts to calculate
precisely how fast stars and other astronomical
objects move toward or away from Earth.
11. Red Shift
•the wavelength of the light is
stretched, so the light is seen as
'shifted' towards the red part of the
spectrum.
12. The radiation emitted by an object moving
away is stretched or red shifted.
Red shift' is a key concept for astronomers. The
term can be understood literally - the wavelength
of the light is stretched, so the light is seen as
'shifted' towards the red part of the spectrum.
13. Big Bang Theory
• is the leading explanation about how the
universe began. At its simplest, it talks
about the universe as we know it starting
with a small singularity, then inflating over
the next 13.8 billion years to the cosmos
that we know today.
14. A 2013 map of the background radiation left over from
the Big Bang, taken by the ESA's Planck spacecraft,
captured the oldest light in the universe. This information
helps astronomers determine the age of the universe.
Credit: ESA and the Planck Collaboration.
15. Steady State Theory
• is an alternative to the Big Bang model
of the evolution of the universe.
• the density of matter in the expanding
universe remains unchanged due to a
continuous creation of matter, thus adhering
to the perfect cosmological principle, a
principle that asserts that the observable
universe is basically the same at any time as
well as at any place.
16. • The term 'steady state' means a stable
condition that does not change over time or in
which change in one direction is continually
balanced by change in another.
• Also referred as the infinite universe theory of
the origin of the universe or continous
creation.
• Proposed by Hermann Bondi, Thomas Gold,
and Sir Fred Hoyle.
17. • states that our universe looks the same from
every spot in it and at every time.
