What is solar system? Theories behind the formation of solar system? Some important facts about solar planet

            

       

                                                               

The universe consists of billions of galaxies, trillions of stars, and so on. These galaxies contain billions of planetary systems. Our galaxy, Milky Way has also billions of planetary systems. But the name of our planetary system is the Solar system. The word solar came from a Latin word that means sun.

      Their many theories related to the formation of our solar system, which can be divided into two categories: -

•        Evolutionary Theories: the theories which suggest that the planets were formed during the evolution of the sun are called an evolutionary theory.

For example –

      Nebular Hypothesis: - This theory was proposed by Kant, the German philosopher in 1755, and Laplace, the French mathematician in 1796.

             There was a large, hot, gaseous nebula in the universe, which rotate along its axis. Since it was hot so it had lost energy or heat to radiation and became cooler. As a result, the nebula was contracted and its speed of rotation increased due to conserving angular momentum. Because of conserving angular momentum, the centrifugal force was also increased. Finally, a stage came when the centrifugal force became greater than the gravitational force of attraction which acted inward. As a result, a ring separated from the nebula. The above process was repeated again and again and successive rings were separated out from the nebula. Slowly these rings were condensed into planets and the central mass of the nebula continued to shrink and finally, our sun was formed.

Defect of Nebula Hypothesis: -

1)      It was not able to explain the energy distribution within the solar system.

2)      According to this theory the sun which possesses most of the mass of the solar system, should have gathered maximum angular momentum. But 98% angular momentum is conserved by the planet and the rest of the 2% angular momentum is present in the sun.

 

·         Catastrophic theory: these theories are those theories that imagine that the planets were formed by special accident, such as close approaches of two stars or by the collision of two stars. For example:

         Planetesimal Hypothesis:  this theory was proposed by Chamberlin and Moulton in 1904

According to this theory, the sun existed before the formation of the solar system. A large star close approached the sun, Due to the strong gravitational pull of the passing star, a giant mass of gas was torn from the surface of the pre-existing sun. This giant mass of gas was broken into small chunks which on cooling give rise to solid particles, called Planetesimal. Planetesimal started flying as cold bodies around the sun and in the plane of passing stars. By collision and gravitational force of attraction, this Planetesimal breaks again into small nine pieces and our planets were formed.

Defect of the Planetesimal hypothesis:

1)      Most of the material which was ejected from the pre-existing sun would come from the interior. It would be so hot that the gas would disappear in the space rather than condense into planets

2)      Although the angular momentum imparted the planets by close approached star would greater than the produced rotation of nebula, the amount is still less than that observed.

 

Gaseous Tidal Hypothesis: This hypothesis was proposed by Jeans and Jeffrey in 1925.

According to this hypothesis, a large star close approached the sun. Due to the gravitational pull of the star on the surface of the sun, a gaseous tide was separate from the surface of the sun. When the star passed near to the sun, the size of the tide increased. As a result, the shape of the tide looked like a spindle being thickest in the middle and thinnest in the ends. This spindle gaseous mass soon broke into ten pieces due to collision and other events of the universe, nine of which condensed into planets and the remaining one further broke into small pieces, forming a group of planetoids.

Defect of this hypothesis:

1)      Most of the material which was ejected from the pre-existing sun would come from the interior. It would be so hot that the gas would disappear into space rather than condense into planets, now there are eight planets in the solar system. The ninth planet, Pluto was declared as a dwarf planet in 2006 by International Astronomical Union (IAU). The planets are rotating on their axis and revolving on their orbits around the sun, which is present in the center of our solar system. The 99.85% mass of our solar system is occupied by the sun and the rest of 0.15% by the planets. The planets in the order of increasing distance from the sun are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. On the basis of location, the planets are divided into two groups:

1)      Inner group: Mercury, Venus, Earth, and Mars. The inner planets are also called terrestrial planets because their surface is solid.

2)      Outer group: Jupiter, Saturn, Uranus, and Neptune. The outer planets are also called juvenile planets because of their gas composition.

 

Mercury:

1)      It is the smallest planet in our solar system. It is slightly larger than Earth’s moon.

2)      It is not known that when was it discovered, although it was first observed through a telescope in the 17^th century by the astronomer Galileo Galilee and Thomas Herriot.  

3)      It is named after the Greek god Hermes, translated into Latin Mercurius Mercury, god of commerce, the messenger of God, a mediator between God and mortals.

4)      Demeter of mercury is approx. 4879.4 km.

5)      The rotational period of it is 58dayss, 15 hours, 30 minutes.

6)      Revolution period of mercury is 88days

7)      The density of mercury is 13.6 gcm^3. It is the second densest planet.

8)      The distance of mercury from the sun is 55.636 million km approx.

9)      The distance of mercury from the earth is 204.51 million km.

10)   Mass of mercury 3.29 * 10^23 kg. It is approx. 0.06 times greater than earth mass.

11)   Surface temperature difference from -173 to 427 degrees Celsius

12)   It does not have any moon and rings

13)   Because of the weak gravitational pull of mercury from the earth, there is a 38% weight difference on the surface of mercury than the surface of the earth.

14)   One day on the surface of mercury = 176 days on the surface of the earth.

15)   As the iron core of the mercury planet cooled and contracted, the surface of the planet became wrinkled. The scientist has named these wrinkles, Lobate Scarps. These Scarps can be up to a mile high and hundreds of miles long.

16)   It is the second hottest planet in our solar system

17)   Owing to its proximity to the Sun, Mercury is a difficult planet to visit. During 1974 and 1975 Mariner 10 flew by Mercury three times, during this time they mapped just under half of the planet’s surface. On August 3rd, 2004, the Messenger probe was launched from Cape Canaveral Air Force Station; this was the first spacecraft to visit since the mid-1970s.

 

Venus:

1)      It is the second – brightest nature object that shines in the night sky after the moon.

2)      Venus was observed by ancient astronomers from different cultures many times however, the first accurate observation was in 1610 by Galileo Galilee.

3)      The diameter of Venus is  12,104 km

4)      The rotational period of Venus is 243 days. It takes a long time to rotate in its axis than other planets in the solar system.

5)      The revolution period of Venus is 224.7 days. Its revolution period takes less time than its rotation period.

6)      The density of Venus is 5.24 g cm^-3

7)      Distance from the sun is 108.46 million km.

8)      Distance from the earth is 118.22 million km

9)      It does not have any moon.

10)   Venus is sometimes called the earth's sister planet because of its similar size, mass, and bulk composition.

11)   Although mercury is present close to the sun, Venus is the hottest planet in the solar system because its thick atmosphere traps heat in a runaway greenhouse effect, making it the hottest planet in our solar system with surface temperatures hot enough to melt lead.

12)   The mass of Venus is 4.87*10^24kg. the mass difference between earth and Venus is 0.82 earth

13)   It does not have any ring and moon

14)   One day on the surface of mercury = 117 days on the surface of the earth.

15)   The surface temperature of Venus is 471 degrees Celsius

 

 

Earth:

1)      Earth formed over 4.5 billion years ago.

2)      Earth revolution period 365 days.

3)      The rotational period is 1 day (23.93 h)

4)      The diameter of the earth is 12,742

5)      Density 5.51 g cm^-3

6)      Distance from the sun is 151.26 million km (1 au)

7)      The name earth is derived from the English and German word “eor (th) e/ertha and erde” which means ground.

8)      Earth-mass 5.92*10^24kg

9)      Surface temperature -88 to 58 degrees Celsius

10)   Earth has a strong magnetic field due to the nickel-iron core. This field protects the Earth from the effects of solar wind.

11)   It has only one natural satellite that is the moon.

12)   It is the only planet not named after a god.

13)   It is the densest planet in our solar system.

 

Mars:

1)      It is the second smallest planet in our solar system

2)      It is called a red planet because of the presence of a lot of iron minerals in its atmosphere.

3)      Olympus Mons which also known as nix Olympia is a site of mars which are the largest volcano and highest known mountain on any planet in our solar system.

4)      One of the largest canyons in the solar system is known as Valles Marineris is also present on Mars.

5)      It has two moons Phobos and Deimos.

6)      Mariner 4 was the first unmanned spacecraft launched by NASA on 24^th November in 1964 who visit Mars.

7)      The rotational period is 1 day, 0 h, 37 min.

8)      The revolution period is 687 days.

9)      Distance from the sun is 208.36 million km

10)   Distance from the earth is 80.078 million km.

11)   The density of Earth is 3.93 g cm^-3

12)   The mass of Mars is 6.39*10^23 kg. the mass difference between earth and Venus is 0.11 earth

13)   The surface temperature of Mars is -87 to-5 degrees Celsius

14)   Only the 18^th mission to Mars have been successful

15)   It has the largest dust storm in the solar system.

16)   Sunset on Mars is blue.

17)   November 2016, NASA reported finding a large amount of underground ice in the Utopia Planitia region of Mars which is a sign of water on Mars.

Jupiter:

1)      It is the largest planet in our solar system.

2)      It is one of the third brightest planets in our solar system which is visible to the naked eye in the night sky after the moon and Venus.

3)      Jupiter has 79 known moons, including four large Galilean moons discovered by Galileo Galilee in 1610.

4)      Ganymede is the largest moon of Jupiter. Its diameter is greater than the planet Mercury.

5)      It’s the fastest spinning planet in our solar system.

6)      The Diameter of Jupiter is 139,820 km.

7)      The Rotational period is 10 hours.

8)      The revolution period is 12 years.

9)      The density of Jupiter is 1.33 g cm^-3

10)   Distance from the sun is 729.58 million km

11)   Distance from the Earth is 653.37 million km

12)   Jupiter has 4 sets of known rings. The name of these rings is the halo ring, main ring, The Am althea gossamer ring, Thebe gossamer ring.

13)   The mass of Jupiter is 1.90*10^27 kg. Its mass is 318 times massive than earth's.

14)   The surface temperature of Jupiter is -108 degrees Celsius.

15)   It has the shortest day on the entire planet.

16)   Jupiter has unique cloud features. The upper atmosphere of Jupiter is divided into cloud belts and zones. They are made primarily of ammonia crystals, sulfur, and mixtures of the two compounds.

Saturn:

1)      It is the second-largest planet in our solar system.

2)      It has at least 82 moons.

3)      Titan is the largest moon of Saturn and the second-largest moon in our solar system.

4)      We cannot stand on the surface of Saturn because it does not have a solid surface. Here the temperature and pressure gradually fall down when we close to the troposphere.

5)      From the inner to outer, the name of Saturn rings are D, C, B, A, F, G, and E

6)      The diameter of Saturn is 116,460 km

7)      The rotational period is 10.2 hour

8)      The revolution period is 29.46 years.

9)      Distance from the sun is 1.4941 billion km

10)   Distance from the earth is 1.3698 billion km

11)   The density of Saturn is 687 kg m^-3

12)   The most common nickname of Saturn is the ringed planet.

13)   It has the fastest wind of any other planet in our solar system.

14)   It is the least dense planet in our solar system.

15)   It appears a pale yellow color because its upper atmosphere contains ammonia crystal

16)   The mass of Saturn is 5.683*10^26 kg

 

Uranus:

1)      Uranus is officially discovered by Sir William Herschel in 1781.

2)      It is called an Ice giant planet. Because its rocky, ice cores are proportionally larger than the amount of gas contained. The gas giants- Jupiter and Saturn contain far more gas than rock or ice. So it is called Ice giant.

3)      Uranus has 27 know moons. Its five name moons are – Veranda, Ariel, Umbriel, Titania and Oberon.

4)      Titania is the largest moon of Uranus and the eighth largest moon in our solar system. 

5)      The diameter of Uranus is 50, 724 km

6)      The rotational period of Uranus is 17 hours 14 min

7)      Revolution period is 84 year

8)      Distance from the sun is 2.96 billion km

9)      Distance from the earth is 2.89 billion km

10)   The mass of Uranus is 8.681*10^25 kg

11)   The surface temperature of Uranus is -195 degrees Celsius

 

Neptune:

1)      It is the fourth-largest planet in our solar system.

2)      It was subsequently observed with a telescope on 23^rd September 1846 by Johann Gale.

3)      It has 14 known moons.

4)      It is the smallest gas giant.

5)      It has a sixth faint ring

6)      The diameter of Neptune is 49,244 km

7)      The rotational period is about 16 hour

8)      The revolution period of Neptune is 164.8 years

9)      Distance from the Sun is 4.47 billion year

10)   Distance from the earth is 4.33 billion km

11)   Mass of Neptune is 1.024*10^26 kg.