Originally Posted by googlechrome

Qurban Bhai and seniors I am stuck once again. Can you add something in outline. That would be very kind.



Man’s Place in universe
Outline
Universe size
Discoveries
Habitable universe
Our place in universe

Introduction
Universe expands beyond our imagination. When we think about a limit, a question about limit blinks in our minds. We ask ourselves what would be out of the limit. This iterative questioning about limits has never been solved by humans. Humans had to bear with the vista of our vast universe with dozens of questions in mind. In dark nights they would look at moon and stars, comets and planets and meteors and wonders of eclipses. For centuries question of our place in this limitless universe of lord bamboozled us. Humans created theories about our place.
In early time of human civilization we had very few knowledge about universe. We said we are the in the centre of universe and everything else revolves around us. Later in 17th century the idea surfaced that this is not the case. Further with the discovery of laws of orbits we depicted solar system and came to the conclusion that we are part of a star-planet system. Now we know that we are a part of Solar system that himself is a part of Milkeyway which is further a part of local-group of galaxies.
According to Earth-Sky blog our galaxy contains nearly 100 billion stars. Nearly 20% of them have a habitable zone where planets orbit. These planets may nourish life. Man has successfully stepped onto moon. Similarly man is near to walk on mars. Presence of water on Martian surface has been conformed although none of the water molecules found till date.
Even today we are not able to answer the question but another version of the same question. What are our immediate surroundings? This is the result of tireless efforts of astronomers and scientists. We are a part of solar system third in number from Mercury to Pluto, the last dwarf planet. We have a moon having its radius almost 1/4th of that of Earth. Solar system sits in the Orion Spur which is a minute arm of Milkeyway between Pursues and Sagittarius arms. Milkeyway is a middle sized galaxy with 100 billion stars. These stars are in variety of sizes, radiations and luminosity. Milkeyway is a member of Local group of galaxies.