The document summarizes key facts about planets and other objects in our solar system. It describes the formation of the solar system 4.6 billion years ago and its composition including 8 planets, moons, asteroids and comets. The planets are divided into terrestrial planets like Earth and Mars that are rocky, and Jovian planets like Jupiter and Saturn that are large and gaseous. Each planet is then briefly described with details about their composition, atmospheres, interiors, moons and other characteristics.

1. EARTH
AND
SOLAR SYSTEM
Ajmal P
Department of Geology
University of Calicut

2. SOLAR SYSTEM
The sun,it’s eight planets and their moon together with smaller objects such as asteroid and
comets is commonly known as solar system.
Solar system were formed 4.6 billion years ago from the gravitational collapse of giant
interstellar molecular cloud.
Solar system consists 165 moons and 1 star (sun).
The eight planets were classified into two groups based on their composition and properties
that is ;
1)Terrestrial planets [inner planets]
2)Jovian planets [outer planets]

3. Terrestrial planets Jovian planets
↓ ↓
Mercury,Venus,Earth,Mars Jupiter,Saturn,Uranus,Neptune

4. TERRESTRIAL PLANETS JOVIAN PLANETS
Close to the sun Far from the sun
Orbits are closely spaced Orbits are widely spaced
They containing small masses Containing large masses
Small radius Large radius
Mainly consisted as rocky composition Mainly consisted as gaseous and ice
Solid surface No solid
High density Low density
Few moons Many moons
No rings Many rings

5. MERCURY
Smallest planet in the solar system.
It covered with circular craters
Equitorial radius 2439km
Mass 3.30*10²³ kg
Average density 5.43g/cm³.
Temperature and atmosphere:
Hottest surface
In equator noon temperature maximum 430ºc
night temperature maximum -730ºc cold.
Interior:
Silicate crust, iron rich interior.
Very high density.
Rotation:
Spins very slowly.It’s rotation period is 58.646 earth days.

6. VENUS
 It is the hottest planet in the solar system (867ºF).
 Venus is mostly like earth in diameter and mass.
 Equitorial radius 6051km
 Mass 4.87*10^24 kg
 Average density 5.24g/cm³.
Venus atmosphere:
• Carbondioxide(Co2) - 96 %
• Nitrogen - 3.5 %
• Very small amount of water vapour and other gases.
• Dense cloud covers the atmosphere, so it prevent us from ever seeing it’s surface directly.
• Clouds are composed of sulphuric acid droplets(volcanic activity).

7. Surface:
• Surface is low, less mountainous, gently rolling plains.
• Two major high land regions are ISHTAR and APHRODITE.
Interior:
Deep interior is similar to earth, an iron core and silicate mantle.

8. EARTH
 The third planet nearest to the sun.
 The shape is orbital spheroidal or geoid.
 Water system creates the environment to sustain life.
 Equitorial radius 6378 km, Polar radius 6356 km, Mean radius 6371 km.
 Ocean covers 70.8 % , land 29.2 %
 Average density 5.514 g/cm³, Diameter 12742 km.
 Mass 5.97*10^24 kg
Chemical composition:
Composed mostly iron (32.1%), oxygen (30.1%), silicon(15.1%), magnesium(13.9%),
sulfur(2.9%), nickel(1.8%), calcium(1.5%), and aluminium(1.5%).

9. Interior:
• Classified into mainly 3 layers that is crust, mantle, core.
• Three discontinuities are Conrad, Mohorovicic, Guttenberg.
• Crust is upper most layer and it is sub divided as oceanic crust (granite) and continental
crust(basaltic rocks).
• Mantle is composed of ultrabasic rocks such as peridotite(olivine and pyroxene).
• Outer core is liquid, Nickel and iron(Nife).

10. MARS
 Supported life 3.7 billion years ago, once had a watery surface.
 Named as roman god of war because of distinctly reddish orange color.
 Equitorial radius 3397 km
 Mass 6.42*10^25 kg
 Average density 3.39g/cm³
Atmosphere:
Martial winds sweep dust and patchy clouds(dry ice and water crystals). Generally clear
enough for astronomers to view it’s surface directly.
• Numerous dunes, craters are present.
• Olympus mons(25km),highest mountain in solar system.
• Dried river beds are present.
• Martial climate was once warmer and then cooled drastically.

11. Interior:
same as earth (crust, mantle, core). Mars global surveyor suggest mars core
may be partly molten.
Moons:
Two tiny moons, Phobos and Deimos.
Phobos
Deimos

12. JUPITER
 It is the fifth planet in the solar system.
 To the ancient romans Jupiter was the king of god.
 Largest planet in the solar system form of radius and mass.
 Equitorial radius 71492km
 Mass 1.90*10^27 kg
 Average density 1.33g/cm³, Diameter 139822 km.
 Mainly composed of gas giants.
Atmosphere:
Mainly consisted hydrogen, helium, hydrogen rich gases such as methane, ammonia and
water.

13. Moons:
• More than sixty known moons are present.
• The four large satellites discovered by Galileo, they are
o IO(3242km diameter)
o Europa(3138 km diameter)
o Ganymede (largest moon in the solar system, 5268 km diameter)
o Callisto (4806km diameter)
IO EUROPA GANYMEDE CALLISTO

14. SATURN
 It is the planet in the solar system.
 Second largest planet.
 Diameter nine times larger than earth (116464 km).
 Surrounded by lovely ring.
 Equitorial radius 60268km, polar radius 54364 km, mean radius 58232 km.
 Mass 5.68*10^26 kg
 Average density 0.7g/cm³
 Mainly composed gas giants.
 Interior:
• Iron nickel core and rock(silicon and oxygen compounds).
• Wind speeds can reach 1800 km/h, higher than Jupiter but not as those on Neptune.

15. Saturn ring:
Ring were first seen by Galileo. Ring are very wide. The main band is 70000 km, lessthan
100m thick, ring are not solid structure.
Moons:
Titan (largest moon in the solar system). Diameter is 5000 km , slightly larger than Mercury.
Very cold.
TITAN

16. URANUS
 It is the seventh planet in the solar system.
 It was god of heaven.
 Equitorial radius 25559 km
 Mass 1.20*10^25 kg
 Average density 1.32g/cm³
 It is composed with ice giants.
 It have similar composition of Neptune.
Atmosphere:
• Rich in hydrogen and methane
• Methane gives deep blue color to the planet.
• When sunlight falls Uranus, methane gas strongly absorb red light and remaining light blue scatteres
into cloud.

17. NEPTUNE
 It is the last planet in the solar system.
 Farthest planet from the sun.
 Similar to Uranus size.
 Mean radius 24622 km.
 Mass 1.02*10^26 kg.
 Named as Roman god of sea.
 Not visible to unaided eye, planet found by mathematical prediction rather than by empirical
observation.
 Composition is ice giants.
Atmosphere:
Primarily of hydrogen and helium along with traces of hydrocarbons and possibly nitrogen, but it
contains a higher proportion of ices, such as water, ammonia and methane.

18. METEORITES
A fragment of solid matter entering to the earth’s atmosphere from the outer space is called
meteoroid (tiny particles).
Small rocky or metallic body in outer space.
Range in size from small grains to one-meter-wide objects.
Meteor is thin trail of light. Left after vaporization of a meteoroid during penetration into the
atmosphere.
Larger meteoroids reach the surface even if they are partially vaporized. Such solid object from
planetary space that has fallen to the earth surface are called meteorites.
Falling by a brilliant flash light(fire ball)
Meteorites is also referred as shooting star.
Nearly 8 billion meteorites entering to the earth surface daily.
Composition:
• Iron and nickel composed(nickel range from 4%-20%)
• Stony material consisting silicate minerals (olivine and pyroxene) 20% less nickel-iron.

19. ASTEROIDS
They are true planets of the sun with small sizes.
Also calles as minor planets.
Composition vary from nickel-iron silicate rocks.
Total number may exceed 50000, majority in between Mars and Jupiter.
The four largest asteroids are:-
1. Ceres (1018 km)
2. Pallas (629 km)
3. Vesta (548 km)
4. Hygiea (450 km)
COMETS
 Small planetary bodies revolving around the sun.
 They are strangest bodies in solar system(invisible)
 Range from near sun to beyond Neptune.
 Composition made up of water, ice, dust and other carbonaceous materials.