Origin and Evolution of the Earth
UNIVERSE
(13.7 billion years old)
Billions of
Galaxies
Milky Way
Galaxy
Solar System
(4.5 billion years
old)

George Lemaitre, a Belgian
priest and a physics
professor proposed The Big
Bang theory which explains
the origin of the Universe
and its expanding nature

The theory explains that the Universe originated billions
of years ago in a rapid expansion from a single point of
nearly infinite energy density. This single point violently
exploded, approximately 13.7 billion years ago, which
led to the expansion of the universe

Edwin Hubble, an American astronomer provided evidence to prove the
expanding universe in the 1920s.
Astronomers are able to
detect an “echo” from the
Big Bang in the cosmic
microwave background
radiation (CMBR). The
CMBR is the remains of
the thermal energy from
the Big Bang spreading
thinly across the whole
Universe. It can be
detected with a radio
telescope. The discovery
of the CMBR is the first
evidence of the Big Bang
The discovery of red-shift in
light from distant galaxies
also led to the development
of the Big Bang theory. Red-
shift of galaxies in general
means the light from
galaxies shifts to longer
wavelengths (redder), which
is why it is called ‘red-
shifted’. Red-shift data
provides evidence that the
Universe, including space
itself, is expanding.
The abundance of
hydrogen and helium
in the Universe
suggests that these
elements were first
formed during the Big
Bang. These lighter
elements are the
precursors for all
other elements.
Evidences

According to Big Bang Theory
1. Whole universe was made up from singularity.
2. singularity- a tiny ball like structure, smaller than atom with infinite temperature and
density
3. About 13.7 billion years ago, that tiny ball exploded and led to formation
of universe.
4. With explosion, universe started to expand (rapid expansion at beginning,
then slowed down)
5. Rate of expansion of universe is not decreasing but increasing.

Difference between big bang theory and solar nebula hypothesis
solar nebula hypothesis
1. The Nebular Hypothesis is an
explanation for the formation of solar
systems.
big bang theory
1. The Big Bang Theory explains the
origins of this universe
2. believes that all bodies in our solar system evolved
from an enormous rotating cloud called the solar
nebula.
2. everything in the universe was once
compressed into a single point.

Formation of Different Planets
• Terrestrial/Rocky Planet (Inner Planets) : Mercury, Venus, Earth and Mars.
These planets were mostly formed from heavy compounds such as
iron, nickel, aluminum and rocky silicate.
• Jovian Planets-Jupiter-like-planets : Jupiter, Saturn, Uranus and Neptune.
These planets are formed from the gases and Icey beyond the frost
line.
Where volatile compounds such as water, ammonia, methane,
carbon dioxide and carbon monoxide to condense into solid ice.