What is a star?
    Every nights when you are getting ready to sleep, you often see many shiny objects in the dark sky when you look out the window, and they are called stars. A star can be cool or burning hot, and it can also be dim or very bright depending on the star's luminosity.
    A star is a massive ball made of a giant cloud of gases and dusts called Stellar Nebula. The star shines because of its energy in the center of itself known as the core. The star makes its own power by going through the nuclear fusion, and thus the power would be made and served for the star to continue shining at night.

What are some different types of a star?
    There many different characteristics of different stars. The stars have different temperatures that make them cool, average, or burning hot. The coolest temperature of a star is 2,000; the hottest temperature of a star is 50,000. The stars have different luminosities that decide how dim or bright they are. The highest luminosity of a star would be 1,000,000, and the lowest luminosity of a star would be 0.001. Also, the size of a star increases when its luminosity gets higher.
    There are many types of stars which are in their different stages, such as main sequence, giants, supergiants, and white dwarfs. The major type of the stars is called the main sequence in which the stars are in their early stages. It includes any temperature, luminosity, color, and spectral type. The other type of the stars is giant, and it includes temperature from 3000 to 10,000 and luminosity from 50 to 1000. Its color can be white-yellow, yellow, orange, and red; its spectral type can be F, G, K, or M. The bigger type of the stars is supergiant. Supergiant includes temperature from 4000 to 40,000 and luminosity from 30,000 to 1,000,000. Like the main sequence, supergiant also contains any colors and spectral types. Last but not least, the white dwarf which is the old stage of the stars includes only the temperatures under 50,000 and the luminosities under 0.01. Its spectral type is D which is different from all the other stars'.

What is a H-R Diagram?
    H-R Diagram stands for Hertzsprung–Russell diagram. It is a kind of graph that shows the statistics of different stars according to their luminosities, temperatures, names, types, sizes, colors, and spectral types by plotting the points, similar to the scatter plot graph.


What is nuclear fusion?
    Nuclear fusion is the process in which the two hydrogen molecules combine and transform into one helium molecule, and thus the energy is made. This process is important for a star to form because it required the energy made by the nuclear fusion once the shrunk cloud is hot enough.


What is the life cycle of a star like?
    There are three major types of stars that have their own unique life cycles: the sun-like star, huge star, and giant star. However, they all begin with the stellar nebula, a giant cloud of gases and dusts.
    Once the stellar nebula gets hot enough and the nuclear reaction takes place, a star is made. After going through the main sequence stage, a sun-like star would then go through the red giant period which the star would get much bigger. After that, the star would explode, and the explosion of the sun-like star is called planetary nebula. Finally, the remains of the star which is called the black dwarf would cool down and become the white dwarf. For the huge star and giant star, they would also become much bigger but called the red supergiant. Similar to the sun-like star, they also explode, and the great explosion is called supernova. Finally, the huge star remains would become the neutron star, and the giant star remains would become the scary black hole.