Universe is the combination of Nebulas, Galaxies and free space. The study of the universe is known as Astronomy in the USA and Cosmology in Russia.
Universe formation theories are:
1 Geocentric theory,
2. Heliocentric theory,
3. Big Bang Theory,
1) Geocentric theory,
This theory was proposed by Ptolemy Earth and is Glayoko at the center, in 140 AD. According to this theory, earth is at the center, all the planets and sun revolve around the earth.
2) Heliocentric theory,
This theory was proposed by Copernicus in 1543AD. According to this theory, the Sun is at the center, all the planets and natural satellites revolve around the sun.
3) Big Bang Theory,
Big bang means a huge explosion. This theory was proposed by George Limator. It is the widely accepted universe formation theory. According to this theory, the Universe has been formed out of the explosion of primordial mass around 13-15 million years ago. Universe is expanding.
Galaxy :
It is a cluster of thousands of millions of starts in the universe. Each galaxy has billions of stars. The galaxy in which the Sun is a part is a Milky Way. And the largest galaxy in the universe is Hydra. The Chinese call the galaxy as the Astor River. Greeks call the galaxy the way to heaven.
Stars :
The birthplace of stars is Nebulas. Stars are self laminating cosmic bodies. The surface of stars is rich in Hydrogen (71%) and Helium (26%). The biggest star is Jetilglux. The nearest star to the earth after sun is Proximal century. The brightest star is Dog star.
Nebulas :
These are hot, revolving cosmic bodies. These are the birthplaces of stars. Nebulas were discovered by Huygens.
Free space: The space between nebulas and galaxies. 97% of the universe is free space.
Solar system:
It is the combination of
(a) Sun, Planets, Natural satellites, Asteroids and Comets
(b) Cooper's belt: this region is located next to Neptune. It contains Dwarf planets and Comets.
(c) Oort cloud region: this region is located next to Cooper's belt.
SUN :
The surface of the sun is of three types.
1 Photosphere:
The temperature on Photosphere is 6000 degrees centigrade. The black spots on this surface are sunspots. The temperature on sun spots is around 1500 degrees.
2 chromospheres :
The temperature on this layer is 32400. It is visible on dawn and dusk,
3. Corona:
The temperature of this layer is 271akh.
The age of the Sun is 5.5 billion years
It takes 8.2 minutes for a sun ray to travel from the Sun to the Earth,
The size of sun is 13 lakhs times of the size of the Earth
Its gravitational pull is 28 times more than that of Earth, Its rotation period is 25 days
Its revolution period is 250 million years
The distance between sun and earth is 149.5 million kilometers
The distance between sun and earth is 147 million kilometers on Perihelion day (On June 3rd) The distance between sun and earth is 152 million kilometers on Aphelion day (on July 4th)
Planets:
These cosmic bodies rotate around their own axis and revolve around the sun in an elliptical orbit. These planets get heat from the sun. Pluto was removed from the list of planets in 2006 by the International Astronomical union at Prague because it does not satisfy the characteristics of a planet.
Pluto is considered as Dwarf planet now.
The largest dwarf planet is Eris
The smallest dwarf planet is Ceres
There are 8 planets in the solar system, They are
l. Mercury
2 Venus
3. Earth
4. Mars
5. Jupiter
6. Saturn
7. Uranus
8. Neptune
Inner planets:
These planets have small size, high density; and high temperatures. These planets are rocks.
Outer planets:
These planets have large size, low density and are formed by gases.
You must be logged in to post a comment.