The Cosmos
Cosmos is a term used in Astronomy as well as Physics. It refers to everything that exists from the smallest atoms to the huge heavenly bodies that are far away from us. This word has come down from the ancient Greek word-kosmos-which means well ordered Universe or world.
The Greeks believed that 'cosmos' was a homogeneous (uniform) system consisting of the Earth, the Sun, the Moon, stars, and other visible planets. However, today we know that the cosmos is far more larger than the one that the ancient people thought it to be The term 'cosmos' is another word for Universe indeed.
Stars come in different colours, hot stars give off blue light, and the cooler stars give off red light.
Cosmology
Cosmology means study of the origin, structure, development, behaviour and future of the cosmos(Universe)
Till the 17th century people believed that everything beyond the Earth's surface was not worth knowing at all.
But then Kepler proved that a number of heavenly bodies (planets) revolved around the Sun. Also Isaac Newton explained how gravity forced the planets to move along their fixed paths. It led the scientists to believe that the laws of Physics were applicable to the cosmic bodies as well.
In 1915. Fred Hoyle, suggested that the 'cosmos' (Universe) has always existed. New matter keeps
being created out of nothing to fill the empty spaces caused due to the expansion of the Universe.
But a few years later, Edwin Hubble put forth the Big Bang Theory regarding the origin of the Universe. This theory came to be accepted finally before long
These theories goaded the scientists and astronomers to take up a regular study of the 'cosmos as an independent branch of science. It is this very branch that has been named cosmology.
The astronomers of today are studying the Universe from various angles. So, new facts and theones sure to be put forth to replace the old ones in the near future.
None of the other planets of the solar system can support life besides Earth. So, life exists only on Earth. However, studies do reveal that a number of star systems may exist with planets capable of producing life forms somewhat similar to our own.
Stars with strong gravity cause themselves to become smaller and smaller and eventually turn into black holes.
What is Universe ?
People in the past thought that the Universe consisted of their own region and other far away regions which they had heard of along with the Sun, the Moon, the planets stars. As for the heavenly bodies, they believed them to be gods and spirits. It was during the 1400's and 1500's that astronomers like Nicolaus Copernicus made new discoveries.
Later on, the invention of Galileo's telescope shattered all the previous wrong beliefs about the Universe and its behaviour. Today, it is rightly believed that the Universe is the whole of space and time and everything in them matter, light, and all other forms of radiation and energy.
Thus, the Universe includes the entire solar system-along with our Earth and everything on it. All the stars including the Sun are the parts of the Universe too. The bodies in the Universe are big as well as small.
Bigger bodies
Billions of stars have formed large groups that are almost circular in shape. Our most powerful telescopes have located at least 10,000 million such 'stars-groups' which are generally called star-systems or galaxies. The galaxies in the Universe tend to form even bigger groups that are called clusters. These huge clusters are also spherical in shape.
That is, not all, indeed. The clusters of galaxies in their turn appear to be grouped into still larger groups which we call super clusters. These giant super-clusters are also circular in form.
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| Super-cluster |
SMALLER BODIES
The super-clusters are the largest coherent (united) bodies, discovered in the Universe so far.
Besides the stars, galaxies, clusters and super-clusters, there are other objects (bodies) too in the Universe. They include planets, satellites, asteroids, comets, meteors and meteorites. All these bodies are scattered' through the emptiness of the space.
Are there any other Universes outside our own? This question still awaits an answer. So, we can say that no other Universe has come to be known so far, except the Universe of which we are a part of it.
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| Galaxy |
Our galaxy has approximately 250 billion stars and it is estimated by astronomers that there are 100 billion other galaxies in the Universe.
This is the second part of the series study of the universe if you haven't read the first part also check it out Study of astronomy.
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