SOLAR SYSTEM

Detailed explanation-1: -Galaxies. A galaxy is a giant, spinning object made of gas, dust, and stars held together by gravity. Galaxies come in different shapes and sizes and can contain billions of stars. Most occur in groups that are also held together by gravity.

Detailed explanation-2: -A nebula is a giant cloud of dust and gas in space. Some nebulae (more than one nebula) come from the gas and dust thrown out by the explosion of a dying star, such as a supernova. Other nebulae are regions where new stars are beginning to form.

Detailed explanation-3: -Stars form in the densest regions of the interstellar medium, or ISM, called molecular clouds. The ISM is the name given to the gas and dust that exists between the stars within a galaxy. It is 99% gas and 1% dust, by mass. Properties of ISM gas in our region of the Milky Way Galaxy: 70% hydrogen.

Detailed explanation-4: -The word is derived from the Greek galaxias (), literally ‘milky’, a reference to the Milky Way galaxy that contains the Solar System.

Detailed explanation-5: -Galaxy: A group or cluster of stars is called a Galaxy, e.g., The Milky Way. Approximately billions of galaxies are there in the Universe. Universe: A limitless vacuum having millions of stars, planets and satellites is called Universe. There is only one Universe.