Planet

  • PLANETS : SOME IMPOTANT FACTS
  • MERCURY

Diameter

4846.6 km

Moons

None

Average distance of the sun

57.6 million km

Time to orbit the sun

88 days

  • Tiny Mercury slightly larger than earth’s moon, races along its elliptical orbit at 176000 kilometre (110000 miles) per hour. This speed keeps it from being drawn into the sun’s gravity field.
  • The created planet has no atmosphere: Days are scorching hot and nights, frigid.
  • Venus

Diameter

12032 kim

Moons

None

Average distances to the sun

107.52 million km

Time to orbit the sun

225 days

  • Earth’s twin in size and mass, scaringly hot. Venus in perpetually yield behind reflective sulphuric acid clouds.
  • Probes and radar mapping have pierced the clouds and carbon dioxide environment to revel flat, rocky plains and signs of volcanic activity.
  • Its surface temperature rises as high as 500* Celsius.
  • It rotates about its axis in opposite direction to that of the other planets.
  • Mars

Diameter

6755.2 km

Moons

2

Average distance to the sun

225.6 million km

  • The Viking probes failed to find any sign of life.
  • Beneath its thin atmosphere, it is barren covered with pink soil and boulders.
  • Long ago, it was more active. The surface is marked with dormant volcanoes and deep chasms where water once freely flowed.
  • Time to orbit about he sun once in 687 Earth-days (or 668 Mars-days).
  • Mars is 1.5 times farther away from the sun than earth, and it receives about half as much heat from it than the earth.
  • In the warmest season, the temperature reaches 15°-20° Celsius, but by the sunset, it drops to freezing temperatures and at night it falls to -100° Celsius or lower.
  • Jupiter

Diameter

141968 km

Moons

14

Average distance to the sun

772.8 million km

Time to orbit the sun

11.9 years

  • Jupiter is 300 times more massive than the earth.
  • The Lightest gases, hydrogen and helium, account for up to 40 per cent of Jupiter’s mass.
  • The temperature in the planet’s centre may be as high as 100,000° Celsius. (estimated).
  • At the same time, on the outside, due to heat losses, Jupiter may be as cold as we observe it from the earth-about minus 140° Celsius.
  • Jupiter’s rotation period is 9 hours 50 minutes.
  • Jupiter radiates 2.5 more heat than it receives from the sun.
  • Saturn

Diameter

119296 km

Moons

20 or more

Average distance to the sun

1417.6 million km

Time to orbit the sun

29.5 years

  • Specific gravity less than 1.0 (If a large ocean were available, Saturn would float in it).
  • The celebrate rings of the golden giant Saturn is composed of thousands of rippling, spiraling bands just 100 feet thick.
  • All the bright Saturanian moons, with the exception of Titan, revolve around it, facing it with the same side.
  • The most interesting saturn’s moon and PHOEBE, which moves in a retrograde sense, and TITAN, the only moon in the solar system with an atmosphere of its own-it consists of methane with, perhaps, some ammonia.
  • Uranus

Diameter

52096 km

Moons

15

Average distance to the sun

2852.8 million km

Time to orbit the sun

84 years

  • Watery Uranus is the only planet that lies on its side, one pole, than the other, faces the sun as it orbits.
  • Voyager-2 found nine dark compact rings around the planet and corkscrew shape magnetic field that stretches for millions of kilometers.
  • Observation of its radio emission at a wavelength of 1.9 centimetres yielded an average temperature of -100°C and -170°C at 11 centimetres.
  • Uranus’s axis is inclined at 98° to its orbital plane, and so it rotates, as it were lying on its side.
  • The rotation period of Uranus is 10 hours 50 minutes.
  • Neptune

 Diameter

9,000 km

Moons

8

Average distance to the sun

4497 million km

Time to orbit the sun

165 years

 

  • Neptune’s atmosphere appears blue in colour.
  • It has no air and is very cold, dark and desolate.
  • Earth

Equatorial Circumference

39,843.00 km

Polar circumference

39,746.00 km

Polar Diameter

12,639.84 km

Equatorial Diameter

12,754.00 km

Equatorial Radius

6,377.00 km

Flattening

0.003367

Volume

1.83´1027 cu cm

Mass (weight)

598´1027 g

Mean Density

5.52 g per cu m

Sun to Earth Ratio

333,432 : 1

Earth to Moon Ratio

81.45 : 1

Superficial Area

510,100,500 sq.km

Land (Excluding Antarctica)

136,675,997.4 sq.km.

Total Land Surface

148,950,800 sq. km.

Total Water surface

361,149,700 sq.km.

Time of rotation on its own axis

23 h. 56 m. 4.09 sec.

Period of revolution round the sun

365 days 5 hours 48 min 45.51 sec.

Inclination of the axis to the plane of the ecliptic

23° 27’

Orbital Velocity

29.87 km per sec.

Escape Velocity

11 km per second

(that is, speed necessary to break away from the earth into outer space)

 

Speed of Rockets

8 km per sec. approx.

(that is, velocity required to counter earth’s gravity and to rise up into the atmosphere)

 

Distance from the sun

 

Aphalian (Maximum)

152 million km

Periphelion (Maximum)

147 million km

Mean*

149.8 million km

  • The mean distance from the earth to the sun (150 million kilometer) translated into flying hours means that a jet air craft capable of 1000 km per hour would need more than 17 years of non stop flying to reach the sun.
  • MOON
  • Circumference: 11,000 km. Diameter: 3475 km. Gravitational pull:1/6th of Earth.
  • Its orbit around earth is elliptical. The maximum distance (Perigee) is 364,000 km. the average distance is 3,82,200 km.
  • All other satellites (except Charon) have sizes below below 1/8th the size of mother planets. But moon is about 1/4th the size of earth.
  • Takes 27 days, 7 hrs, 43 min and 11.47 sec to complete one revolution around earth.
  • Rotates on its axis in exactly the same time as it takes to complete one revolution. That is why we see only one side of the moon (only 59% of its surface).
  • To our unaided vision, moon seems to be made-up of bright and dark patches. The bright parts are the mountains and highlands, while the darker patches are low-lying planes.
  • The highest mountains on moon are Liebnitz Mountains, which are 10,660 m high.They are situated at moon’s South Pole.
  • Moon has no atmosphere, no twilight and no sound.
  • Moonlight takes 1.3 sec to reach earth.
  • It has a low albedo (amount of sunlight reflected). It reflects only 7% and the rest is absorbed (Earth: 30%, Venus: 70%)
  • Neil Armstrong and Buzz Aldrin reached moon on July 20, 1969 on Apollo XI and set the foot on July 21, 1969 (landing spot is called Sea of tranquility).