Astronomy is not just about the stars. Astronomy is about the constellations, the nine planets, the sun and the moons. The solar system is very complex and has many extraordinary objects.
There are four different types of stars: Protostars, Bright Stars, Red Giants, and White Dwarfs. Protostars are stars that are on the verge of being born. They are glowing clouds of dust and gas. Gravity pulls on every atom moving them towards the center of the cloud of dust, which causes the Protostar to collapse. Over a period of twenty million years the star begins to form and 10 million years after the pocket of gas was formed, a star is born.
The second types of stars are called Bright Stars. They are formed when the new star has completed about 35 million years of its life cycle. A star’s life cycle is a lot like a human’s life cycle, except a star’s years are in millions. When a star is about 10 million years old it is in the same stage on average as a regular human that is about twenty years old. The birth and death rate of stars is called Stellar Evolution. A Bright Star is made when nuclear fusion doubles the size of the star.
The third types of stars are called Red Giants. They are made because the outward flow of the star’s core energy stops. Gravity then steps in and squeezes the star to make it decrease in size. The core of the star’s heat increases and it starts releasing small amounts of energy, the energy holds a large amount of hydrogen gas. The star then begins to grow larger, but it does not get brighter. As a result of the sudden and fast temperature drop, the star’s color changes from blue-white to a red color. Most Red Giant stars have been found in groups called Globular Clusters. Globular Clusters are groups of up to one million stars that move through space.
The fourth type of stars are called White Dwarfs. When a White Dwarf is made the star begins cooling off. As a result of cooling, the outer gas layer spreads out. The star’s temperature drops and makes the gas layer spread out even more. Eventually, the outer layer spreads out so far that the gas layer separates from the star. Then, a Planetary Nebula (cloud of glowing atoms), moves in all directions. The star’s core isn’t giving out any more energy and is to the point of collapsing slowly. All of the matter that the star had in the beginning is still there, but it is compressed more tightly. Because it is packed so tightly the star is now as big as planet Earth. The star is still very hot. Because it is so hot it gives off a glowing white light. This star is called a "White Dwarf" because of its color. Out of the twenty stars that are closest to the Earth, two are White Dwarfs.
The next big thing about the solar system is the Planets. The nine planets play a big part in our solar system. Astronomers have been studying them for a long time but there are still many things to learn about them. The nine planets are Earth, Jupiter, Uranus, Pluto,...