1) The Solar System consists of the Sun and objects that orbit it, including 9 planets. 2) The planets follow elliptical orbits around the Sun due to the balance between gravitational pull and inertia. 3) There are several theories for how the Solar System formed, with the most widely accepted being the Nebular Hypothesis where a large cloud collapsed and spun to form a disk that condensed into planets.

1. The Solar System

2. What is Solar System?
• The Solar System is the
gravitationally bound system
comprising the Sun and the objects that
orbit it, either directly or indirectly.
Our solar system is elliptical in shape.
That means it is shaped like an egg.
The Sun is in the center of the solar
system. Our solar system is always in
motion.

3. elliptical
Elliptical egg

4. What’s in Our Solar System?
• Our Solar System consists of a
central star (the Sun), the nine
planets orbiting the sun, moons,
asteroids, comets, meteors,
interplanetary gas, dust, and all
the “space” in between them.

5. How did the planets get their
names?
All of the planets, except for Earth, were
named after Greek and Roman gods and
godesses. Jupiter, Saturn, Mars, Venus and
Mercury were given their names thousands of
years ago. The other planets were not
discovered until much later, after telescopes
were invented. The tradition of naming the
planets after Greek and Roman gods and
goddesses was carried on for the other planets
discovered as well.

6. Mercury was named after the Roman god of travel.
Venus was named after the Roman goddess of
love and beauty. Mars was the Roman god of
War. Jupiter was the king of the Roman gods,
and Saturn was the Roman god of agriculture.
Uranus was named after an ancient Greek king of
the gods. Neptune was the Roman god of the
Sea. Pluto, which is now classified as a dwarf
planet, was the Roman god of the underworld.
The name Earth is an English/German name which
simply means the ground.

7. Inner and Outer Planets
• Inner Planets:
–Mercury
–Venus
–Earth
–Mars
• Outer Planets
–Jupiter
–Saturn
–Uranus
–Neptune
–Pluto

9. The Relative Size of the Planets
in the Solar System

10. The Sun
• The sun’s energy comes from
nuclear fusion (where hydrogen is
converted to helium) within its
core. This energy is released from
the sun in the form of heat and
light.
• Remember: Stars produce light.
Planets reflect light.
• A star’s temperature determines its
“color.” The coldest stars are red.
The hottest stars are blue.

11. The 9 Planets of the Solar
System
• Planets are categorized according to
composition and size. There are two
main categories of planets:
–small rocky planets (Mercury,
Venus, Earth, Mars, and Pluto)
–gas giants (Jupiter, Saturn, Uranus,
and Neptune)

12. Characteristics of Small Rocky
Planets
• They are made up mostly of rock and
metal.
• They are very heavy.
• They move slowly in space.
• They have no rings and few moons (if
any).
• They have a diameter of less than
13,000 km.

13. Mercury
• Mercury has a revolution
period of 88 days. Mercury
has extreme temperature
fluctuations, ranging from
800F (daytime) to -270F
(nighttime).
• Even though it is the
closest planet to the sun,
Scientists believe there is
ICE on Mercury! The ice is
protected from the sun’s
heat by crater shadows.

14. Venus
• Venus is the brightest
object in the sky after the
sun and moon because its
atmosphere reflects
sunlight so well. People
often mistake it for a star.
• Its maximum surface
temperature may reach
900F.
• Venus has no moons and
takes 225 days to
complete an orbit.

15. Earth
• Earth is the only planet
known to support living
organisms.
• Earth’s surface is composed
of 71% water.
– Water is necessary for life on
Earth.
– The oceans help maintain
Earth’s stable temperatures.
• Earth has one moon and an
oxygen rich atmosphere.

16. • Like Earth, Mars has ice caps
at its poles.
• Mars has the largest volcano
in our solar system:
Olympus Mons. Olympus
Mons is approximately 15
miles high.
• Mars appears red because of
iron oxide, or rust, in its soil.
• Mars has two moons and
takes about two years to
complete an orbit.
Mars

17. Pluto
• Pluto has only one moon
and takes about 249 years
to orbit the sun.
• Part of Pluto’s orbit passes
inside that of Neptune, so
at times Neptune is the
planet farthest from the
sun.
• Pluto was located and
named in 1930, but today
Pluto is no longer
considered a

18. Characteristics of Gas Giants
• They are made up mostly of gases
(primarily hydrogen & helium).
• They are very light for their size.
• They move quickly in space.
• They have rings and many moons.
• They have a diameter of less than
48,000 km

19. Jupiter
• Jupiter is the largest and
most massive planet.
• It’s diameter is 11 times
bigger than that of the
Earth’s.
• It takes about 12 years
for Jupiter to orbit the
sun.
• Jupiter has 16 known
moons.

20. Saturn
• Saturn is composed almost
entirely of hydrogen and
helium.
• Saturn has many rings
made of ice. Saturn’s rings
are very wide. They
extend outward to about
260,000 miles from the
surface but are less than 1
mile thick.
• Saturn has 18 known
moons, some of which
orbit inside the rings!
• It takes Saturn about 30
years to orbit the sun.

21. Uranus
• Uranus is blue in
color due to
methane gas in its
atmosphere.
• Uranus has 11 dark
rings surrounding
it.
• Uranus has 21
known moons and
takes 84 years to

22. Neptune
• Neptune has the
fastest winds in the
solar system: up to
2,000 km/hr.
• Neptune is also blue
in color due to
methane gas in its
atmosphere.
• Neptune takes 165
years to orbit the sun
and has 8 moons.

23. Isaac Newton
Planet in their orbit around the
sun . It was Isaac Newton who
unraveled the mystery of orbital motion
with his Universal Law of Gravitation.
According to Newton, two forces hold
or keep the planets in their orbit around
the sun.
1. Gravitational pull- the force of attraction
exerted by the sun to the planets to be drawn
towards it.
2. Force at Inertia- The force exerted by the
body to throw itself off into space.

24. How the Solar
System Evolved?

25.  PLANETISIMAL
Georges Comte de Buffon, a French
scientist, proposed in 1778 this theory.
According to the theory, ages ago, the sun
collided with another star.The collision
caused large masses of materials from the
two stars to be thrown off into space.
Eventually, the materials cooled and
condensed to form smalll bodies that in the
caourse of time, became planets.

26. PLANETISIMAL

27.  THE COMPANION STAR
THEORY
Fred Hoyle, a British astronomer,
proposed this theory. According to the theory,
the sun once had a companion star. This star
exploded when it collided with the sun and its
materials were held by the sun's gravitation.
From these materials , various planets and
other bodies in the solar system were formed.

28. THE COMPANION STAR
THEORY

29.  THE NEBULAR
HYPOTHESIS
Marquis De Laplace, a French astronomer,
proposed the theory in 1796, According to this
theory, the source of the material of the solar
system was a vast, saucer-shapped nebula
similar to a protostar. This nebula was swirling
slowly in space. The swirling nebula eventually
cooled and shrank, causing it to spin faster in
space. The spinning caused rings of materials
to break away from its outer edge. The rings
gave rise to planets, and the center of the
nebula condensed and became the sun.

30. THE NEBULAR
HYPOTHESIS

31.  GASEOUS OR TIDAL
THEORY
Gaseous or tidal theory by Sir James
Hopwood Jeans and Harold Jeffreys,
proposed in 1917 is a modification of
Planetesimal Theory. According to this
theory, another sun passed in our own sun.
Some parts of our sun is absorbed by the
another sun. The absorbed parts are cooled
and become a planets and satellites.

32. GASEOUS OR TIDAL
THEORY

33.  BIG BANG THEORY
Lemaitre explained his
hypothesis that is Big Bang Theory,
that the universe began when a fiery
material called the primordial fireball
suddenly exploded in the sky. As a
result of the explosion. The material
consists of hot items were spread and
become planets and stars.

34. BIG BANG THEORY
Primordial Fireball

35.  ENCOUNTER HYPOTHESIS
One of the earliest theories for the formation of
the planets was called the encounter hypothesis. In
this scenario, a rogue star passes close to the Sun
about 5 billion years ago. Material, in the form of hot
gas, is tidally stripped from the Sun and the rogue
star. This material fragments into smaller lumps
which form the planets. This hypothesis has the
advantage of explaining why the planets all revolve
in the same direction (from the encounter geometry)
and also provides an explanation for why the inner
worlds are denser than the outer worlds.

37. 1. He is a French Scientist that proposed the
Planetisimal Theory.
2-3. What are the two forces hold or keep the planets
in their orbit around the sun.
4. It is the gravitationally bound system comprising
the Sun and the objects that orbit it, either directly
or indirectly.
5. It is the shape of our Solar System.
6. Where is the sun’s energy comes from?
7. Venus was named after the ___________________.
8. According to this theory, ages ago, the sun collided
with another star.
9. Marquis De Laplace, a French astronomer,
proposed the Nebular Hypothesis in _____.
10. How did the planets get their names?

38. 11. One of the earliest theories for the formation of the
planets.
12. It is the largest and most massive planet.
13. Give one Characteristics of Small Rocky Planets.
14. According to this theory, another sun passed
in our own sun. Some parts of our sun is
absorbed by the another sun. The absorbed
parts are cooled and become a planets and
satellites.
15. Our Solar System consists of a __________.
 ( GIVE ATLEAST TWO EXAMPLE )

40. 1. Georges Comte de Buffon
2-3. Gravitational pull and Force of
Inertia
4. Solar System
5. elliptical
6. nuclear fusion
7. Roman goddess of love and beauty.
8. Planetisimal
9. 1796
10. Planets get their names after Greek
and Roman gods and godesses

41. 11. Encounter Hypothesis
12. Jupiter
13. They are made up mostly of rock and metal.
• They are very heavy.
• They move slowly in space.
• They have no rings and few moons (if any).
• They have a diameter of less than 13,000 km.
14. Gaseous or Tidal Theory
15 . - sun - meteors
-nine planets - interplanetary gas
- moon - dust
- asteriod - all the space
- comets