 |
In the above diagram the numerical values are represented in Astronomical unit. 1 Astronomical unit(AU) is equal to 150 million kilometre.
In the image shown above, the region after Neptune and before Termination shock is known as Kuiper Belt and everything found in this region naturally are called Trans-Neptunian Objects or Kuiper belt objects.
Kuiper Belt Object or Trans-Neptunian Objects: They are the celestial objects beyond the Neptune orbiting the Sun, it extends from nearly 34AU to 55AU. It is known to have 4 dwarf planet. In addition it is known to have short period comets.
Termination Shock: It is region where solar system comes to an end. It can be considered as the boundary of solar system.
Heliopause: It is even beyond termination shock and is a region where effect of sun comes to an end.
Oort Cloud: It extends from nearly 5000AU to 1 lac AU. It is basically a nebula. Long period comets are set to originate from oort cloud and said to take about 30 million year to complete revolution.
Alfa Centauri: Is currently the closest star to our solar system.
SUN
The sun is the star at the center of solar system. Sun consist of about 92% of hydrogen and 8 % helium. That means some of the hydrogen is already converted into helium. It has six regions named as Core, radiative zone, convective zone, photosphere, chromosphere and corona.
- Core: Temperature in the core of sun is around 1.5 * 10^7 degree Celsius. Hence thermonuclear reaction takes place here in core where the hydrogen is converted into helium.
- Radiative Zone: It is the zone between the core and the outer convective zone. Energy generated in core moves out to this zone through radiation and light radiates from this zone.
- Convective zone: Heat is transfered from core through convection.
- Photosphere : This zone is what we see as a sun. This is only part of the sun from where light is emitted. Thickness of this zone is around 500km and light takes 8min to reach the earth from here. This zone is also relatively cooler than other region and temperature here is around 5500 degree Celsius. On photosphere, we have the sun spots. These are regions of high magnetic field and low temperature, here light emit is dim and it appears as a dark spot. Sun spot has a cycle of 11 years.
- Chromosphere: It is the second most outer layer of the sun. Temperature here gain increases upto 2 million degree celsius. It is relatively transparent and hence photosphere appears to be as the sun. This region also emit light but the light is so dim compared to photosphere and hence we are unable to see this region.
- Corona: It is the outer most region of sun. It becomes very hot and leads to coronal mass ejection. This region also emit light but the light is so dim compared to photosphere and hence we are unable to see this region.
Planets and Exo-Planets
The IAU(International Astronomical Union) redefined the term planet in year 2006 to have the following characteristics:
- Planet should revolve around the sun in an fixed orbit.
- It should not be a natural satellite.
- It should have sufficient mass to attain a nearly round shape i.e Hydrostatic Equilibrium.
- It should have cleared its orbital neighborhood of any other object. Simply means that in an orbit of the planet, no other object must follow that orbit or no overlapping orbit.
Pluto fulfilled 1st three condition but failed to satisfy the fourth condition as it had overlapping obit with Neptune and so it lost its planetary status.
The 1st four planets of our solar system also called inner planets are Terrestrial Planet i.e solid surface planets. The outer four planets are called Jovean Planets i.e Gaseous Planet. Out of these outer four planets, the last two planet (Uranus and Neptune) are called Ice Giants. These all planets are said to be formed with the formation of the sun. Jupiter is known to have a Great Red Spot. Great red spot is a storm like condition where the wind velocity is extremely high. There are also white oval shaped storms which are also called string of pearls.
Most of the planet in our solar system rotate and revolve anticlockwise i.e Prograde motion( West to East) when seen from north. Venus and Uranus rotate clockwise i.e Retrograde motion (East to West). Uranus is 1st to be discovered from a telescope and its axis is tilted so much that it seems that it is rolling on its orbit.
Exo-planets are the planets beyond are Solar System. Most of the exo-planets are found by Kepler's Telescope. Many of the exo-planets called as Hot Jupiters have been found, they are called so because of their size similar to Jupiter but are hot due to their proximity as they are very close to their star.
There is an exo-planet named as Gliese 581g which was found in 2010 in Goldilock Zone of another star. Goldilock zone is the region around a star which is habitable and hence the planet in this region could be possibly habitable, goldilock zone of our sun extends upto 1.34AU.
Dwarf Planet: These are planet like objects which just do not fulfill the last condition of planet according to IAU. Pluto is now a dwarf planet. As of now, there are confirmed five dwarf planet in our solar system named as Pluto, Iris, Haumea, Makemake and Ceres. Ceres is dwarf planet in Asteriod belt and the largest asteroid in the asteroid belt. Pluto, Iris, Haumea, Makemake are also called trans-neptunian objects as they are beyond Neptune.
Minor Planets or Asteroids: These are rocky remnants left over after the formation of the solar system. They are found between mars and Jupiter. They orbit around the sun in an asteroid belt. These can be big as 1000 km to a less than 1 km in length. They have an irregular shape.
Atmosphere
Mercury has a very thin atmosphere. Venus has very thick CO2 rich atmosphere. Earth's atmosphere is rich in nitrogen and oxygen. Mars atmosphere is rich in CO2. Jupiter and Saturn atmosphere rich in hydrogen and helium. Uranus and Neptune are rich in ammonia and methane.
Planetary Rings
Initially the planetary ring were known to Saturn only but now every outer planet has planetary ring. Jupiter has 1 planetary ring and Saturn has 7 planetary ring. Uranus has 13 rings and Neptune has 6 ring.
 |
| Saturn planetary ring |
Magnetic Field
Almost all planet have magnetic field except Venus and Mars. Magnetic field of planet is created by magnetic material core for example earths core consist of Nickle-Iron core. Magnetic field create a magneto sphere around a planet which protect the planet from any charge particles or solar winds from sun.
Earth's magnetic field loop is not full and has a opening from where some of the charged particle get into the atmosphere and react with atmosphere to create a lightning kind of phenomenon i.e moving light phenomenon called Aurora. Aurora in northern hemisphere is called Aurora Borealis and Aurora in southern hemisphere is called Aurora Australis.
 |
| Aurora |
Meteoroid, Meteor and Meteorite
Meteoroid: They are the celestial object which under the influence of a planet or satellite or comet travel towards these. They are called meteoroid till they enter the atmosphere of respective object.
Meteor: When meteoroid enter into atmosphere and get burned up completely before landing, they are called meteor. Their ash reaches earth as space dust.
Meteorites: It is the meteoroid which land on the planet, satellite etc and hence create an impact. Example Barringer meteorite crater in US.
Natural Satellite
Mercury and Venus has no natural satellite. Earth has 1 natural satellite called Moon. Mars has two natural satellite named as Phobos and Deimos. Jupiter has 67 natural satellites and the largest one is named as Ganymede. Ganymede is the largest natural satellite of our solar system. Saturn has 62 natural satellite and largest one is named as Titan. Titan is 2nd largest natural satellite of our solar system. Uranus has 27 and Neptune has 14 natural satellites. Even the Dwarf planets has natural satellites. Pluto has 5, Iris has 1 and Haumea has 2.
Comet
A comet is a celestial object which revolve around the sun, in a non-concentric orbit i.e orbit overlaps orbit of other planet. Comet while travelling very close to sun warms up its gases in the process creating a tail which always points opposite to direction of sun. Comets from Kuiper belt are called short period because they will not take more than 200 years to complete a revolution.
0 Comments