Universe

Solar System

• The sun, eight planets, satellites and other celestial bodies (asteroids and meteoroids) form the Solar System
• The sun is at an average distance of about 93,000,000 miles (150 million KM) away from Earth.
• Aryabhata was a famous astronomer of ancient India.
• All nine planets move around the sun in fixed paths.
• Light travels at the speed about 300,000 km per second.
• The light of sun takes about 8 minutes to reach the earth.
• Our earth has only one satellite, that is moon which is about 3,84,400 km away from us.
• Neil Armstrong was the first man to step on the surface of moon on 20 July 1969

0. Sun

• Age: 4.603 billion years
• Radius: 695,508 km (43,450 miles)
• Surface temperature: 5,778 K
• Mass: 1.989 × 10^30 kg (Occupies 99.85% in solar system)
• Distance to Earth: 149,597,870 km (92,960,116 miles)
• Chemical Composition: 71% of Hydrogen, 26.5% Helium and 2.5% of other elements
• The sun rays take 8 minutes to reach the earth
• Sun's Gravity keeps solar system together (90 kg on Earth = 2,520 kg on Sun)

1. Mercury

• Romans named it after their swift-footed messenger god.
• Smallest planet.
• Closest planet to the sun.
• Surface Gravity: 3.7 m/s^2.
• It has magnetic field.

2. Venus

• Named for the Roman goddess of love and beauty.
• Second planet from the sun.
• Terribly hot (even hotter than Mercury), with toxic atmosphere.
• Venus and Earth are often called twins because they are similar in size, mass, density, composition and gravity.
• Magnetic field: 0.000015 times that of Earth's field.

3. Earth

• Third planet from the sun.
• Two-thirds of the planet is covered by Ocean.
• Rich in life-sustaining nitrogen and oxygen.
• It's not a perfect sphere (squashed sphere).
• The hottest spot is in Libya.
• The coldest place is in Antarctica.

4. Mars

• Named for the Roman god of war.
• Fourth planet from the sun.
• A.K.A Red Planet.
• Has both the highest mountain and lowest valley in solar system.
• It's a cold and dusty place.

5. Jupiter

• Named for Ruler of the Roman gods.
• Biggest planet in solar system.
• Fifth planet from the sun.
• Mostly gaseous world, mostly with hydrogen and helium.
• Has Great Red Spot, a giant storm which has raged for hundreds of years.
• Has a strong magnetic field.
• Has dozens of moons.

6. Saturn

• Named for Roman god of agriculture
• Sixth planet from the sun.
• It is known most for its rings made of ice and rock.
• The gaseous planet is mostly hydrogen and helium.
• It has numerous moons.

7. Uranus

• Named for personification of heaven in ancient myth.
• Seventh planet from the sun.
• It's the only giant planet whose equator is nearly at right angles to its orbit.
• Methane in the atmosphere gives Uranus its blue-green tint.
• It has numerous moons and faint rings.

8. Neptune

• Named for Roman god of water.
• Eighth planet from the sun.
• Known for strong winds.
• It is far out and cold.
• Discovered in the year 1846.

# Planets Summary:

	Orbit (Earth's)	Day (Earth's)	Distance (AU)	Radius (Earth's)	Mass (Earth's)	Rotation (Earth's)	Moons	Orbital Inclination	Orbital Eccentricity	Obliquity	Density (g/cm3)
Sun	-NA-	-NA-	0	109	332,800	25-36*	9	-NA-	-NA	-NA-	1.410
Mercury	88 Days	58.6 Days	0.39	0.38	0.05	58.8	0	7	0.2056	0.1°	5.43
Venus	225 Days	241 Days	0.72	0.95	0.89	244	0	3.394	0.0068	177.4°	5.25
Earth	365.24 Days	23 hrs, 56 min	1.0	1.00	1.00	1.00	1	0.000	0.0167	23.45°	5.52
Mars	687 Days	24 hrs, 37 min	1.5	0.53	0.11	1.029	2	1.850	0.0934	25.19°	3.95
Jupiter	11.9 Yrs	9.8 Hrs	5.2	11	318	0.411	16	1.308	0.0483	3.12°	1.33
Saturn	29.5 Days	10.5 Hrs	9.5	9	95	0.428	18	2.488	0.0560	26.73°	0.69
Uranus	84 Yrs	18 Hrs	19.2	4	17	0.748	15	0.774	0.0461	97.86°	1.29
Neptune	165 Yrs	19 Hrs	30.1	4	17	0.802	8	1.774	0.0097	29.56°	1.64
Pluto	248 Yrs	6.4 Days	39.5	0.18	0.002	0.267	1	17.15	0.2482	119.6°	2.03

Note:

• AU = astronomical unit - The average distance from the Earth to the Sun; 1 AU is 149,597,870 kilometers (92,960,116 miles).