Question

some special notes on universe chapter!! pls don't give bad ansswer tommorrow is my exam

Answer 1

Universe is a huge space which contains everything that exists.
The width or extension of universe is about 100000 light years.
The distance between earth and sun is measured in astronomical unit
1AU=1.5*10"m
The distance travelled by the light in one year is called light year.
1 light year =9.5*10^15m
The distance at which mean radius of the earth sustends an angle of second of arc is called parsec
1 parsec =3.1*10^16m

Answer 2

The univere is all about spacetime(space and time) and its contenents which include planets , stars , moon , etc.It size is still unknown . 
TThe Big Bang theory is the prevailing cosmological description of the development of the Universe. Under this theory, space and time emerged together 13.799±0.021 billion years ago[2] with a fixed amount of energy and matter that has become less dense as the Universe has expanded. After the initial expansion, the Universe cooled, allowing the first subatomic particles to form and then simple atoms. Giant clouds later merged through gravity to form galaxies, stars, and everything else seen today. It is possible to see objects that are now further away than 13.799 billion light-years because space itself has expanded. This means that objects which are now 46 billion light years away can still be seen in their distant past, because at that time they were much closer to us.he earliest scientific models were developed by ancient Greek and Indian philosophers .Over centuries ,more precise and astronomical observations led to Nicolus Copernicus to develop the helioucentric model with the sun at the centre of the solar system .