Written by: Yalam Dev Pradhan - 28014, Grade VII
Posted on: 31 August, 2022
The universe is all of space and time. It includes planets, stars and galaxies. It also has matter and energy. The big bang theory is the prevailing description of the development of the universe. According to the theory, space and time emerged together billions of years ago and the universe has been expanding since. The size of the universe is unknown. It is possible to be the size of the observable universe which is like the size of 93 billion light-years in the present day. The earliest models of the universe were made by the Ancient Greeks and the Indian Philosophers.
Galaxies:- A galaxy is a gravitationally bound system of stars, stellar remnants, gas, dust etc. The word is derived from the greek galaxias milky is a reference to the milky way galaxy that contains the Solar System. Galaxies range in size from Dwarfs and a few hundred million stars to giants with one hundred trillion stars.Galaxies are categorised according to their visual morphology as Spiral and Irregular objects. Many have Supermassive blackholes at their centres. The Milky Way's central black hole is known as Sagittarius. It also has mass four million times greater than the Sun's mass.
Solar System:- The solar system is a part of our galaxy. Our solar system consists of 8 planets. It used to be 9 but Pluto broke out of its orbit and is roaming around the solar system. The 8 planets in order are: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. It has many stars. The nearest one is the Sun. The 8 planets in order of their size by radius are: Jupiter(69,911KM), Saturn(58,232KM), Uranus(25,362KM), Neptune(24,622KM), Earth( 6,371KM), Venus(6,051.8KM), Mars(3,389.5KM) and Mercury(2,439.7KM).
Planets:-Planets are large astronomical bodies that are neither a star nor a stellar remnant. There are at least 8 planets in our solar system that still exist: the terrestrial planets:- Mercury, Venus, Earth and Mars and the giant planets:- Jupiter, Saturn, Uranus and Neptune exist here. They are separated by an asteroid belt.
The universe is everything. It includes all of space, and all the matter and energy that space contains.
