STARS
Stars are giant spinning balls of hot gases. Like massive nuclear power stations, they produce vast amounts of energy in the form of heat and light, which they radiate across space as they shine.
They may look like tiny points of light in the night sky, but many stars are incredibly big. Betelgeuse, in the constellation of Orion, is 800 times the size of the Sun, our local star. Stars vary enormously according to the amount of light they emit. Some of the most powerful give off more than 100,000 the light of the Sun, while others are 100,000 times weaker.
Stars are born when clouds of dust and gas in space, known as nebulae, compress together under the force of gravity to become dense “blobs”, called protostars. It is not certain why this happens. Maybe the pressure of an exploding star nearby at the end of its life triggers the process.
After a star has formed it becomes a stable “main sequence” star. The Sun is a typical star of average brightness. More massive stars, like Rigel (also in Orion), glow blue-white, while at the other end of the scale, a white dwarf, the collapsed core of an old star, is no bigger than the Earth.
A star begins its life as a dense mass of gas and dust called a protostar (1). The core becomes so hot that nuclear reactions start deep inside it. Gas and dust are blown away (2), although some remain in a disc surrounding the new star. Planets may form here (3). The star is now a main sequence star (4). When the fuel it uses to produce energy runs out, the core collapses and the star swells into a red giant (5). A massive star will become a supergiant that will blast apart in a mighty explosion called a supernova (6). It ends its days as a neutron star or a black hole (7). A red giant will puff away into space, leaving behind a white dwarf.
Picture Credit : Google