DeeVas

  Light Year: Light year is an astronomical unit. It is used to express the astronomical distance between the celestial objects . A light year is the distance travelled by the light in vacuum in one year. It has nothing to do with the time, it is the measurement of length. It is represented by the symbol ‘ly’ One light year is equal to 9.46 trillion kilometers (9.46×10 12  km) and  63241.1 AU . Calculation of 1ly: The velocity of light is  299 , 792 , 458   m s -1 Which means, the light travels  299 , 792 , 458  m  every second. For 1 second = 299,792,458 m for 60 seconds =  60 × 299 , 792 , 458  m   for 60 minutes =    60 × 60 × 299 , 792 , 458   m for 24 hours =  24 × 60 × 60 × 299 , 792 , 458   m   for 365.25 days =  365.25 × 24 × 60 × 60 × 299 , 792 , 458  m Therefore, 1 LY =  9.461 × 10^ 15   m. While dealing with the galaxies and the stars the measure of their distances if c...

The birth and death of various stars occurs every second in the universe. In our previous blog we saw about “Nebula -the nursery of stars”. Stars are the building blocks of the galaxies. So now let’s see how stars comes into existence from the nebulae. The nebula is made of 99% hydrogen . After nebula formation the interstellar materials starts to cool . Due to this, atom, ions and particles comes together (formation of clumps) and compression occurs. Owing to this the nebulae contracts and splits into separate clumps of different masses. Each clump will try to evolve as an individual star. Since the density of clumps is high the temperature will eventually increase. Because of it’s high mass gravitational force starts to play it’s role. This clump will undergo further contraction. Eventually the temperature and density of the clumps will increase and thus they are recognized as a protostar having a developed photosphere. In case if the mass of the clumps is too small, then it wi...

  An illustration of one of the brightest and most energetic supernova explosions ever recorded. Image credit: NASA/CXC/M.Weiss A star that suddenly increases greatly in brightness because of catastrophic explosion that ejects most of it’s mass. The first ever observation of the supernova on earth was by the Chinese astronomers and skywatchers in 185 A.D., which is known as “guest star” that was visible for eight months.                                                         Stars are alike lives that dwell on Earth. They are born, live and finally die. The stars having the mass more than 1.40 times the mass of the sun undergoes supernova explosion. Generally, a star is stable because it’s gravitational inward force is balanced by the outward pressure created by the nuclear fusion that takes place in it’s core. But when the core turns i...

Nebula is a stellar object which is also known as the ‘star nursery’ (birth place of stars).   The nebula was first recorded by Ptolemy in his book ‘Almagest’ around 150 AD. With the parallel advancement in optics, several nebulae were observed and reported. What is Nebula: Our universe is filled with random gas and dust particles which are collectively known as Interstellar Medium (ISM) . Nebula is a spot where a giant cloud of dust and gas in space. More than one nebula is known as nebulae. It is originated from a Latin word ‘nebula’ which means “mist, vapour, fog, smoke, exhalation”. Birth of Nebula: Some nebulae are formed by gravitational collapse of interstellar medium Some nebulae are formed by supernova explosion . Types of nebula: Nebula is classified into four types. Diffuse Nebulae: Most of the nebulae fall under this category and it is further divided into two categories based on their response to the visible light.     1.Emission nebulae: ...