Interesting Facts About Stars
A star is a mass of incandescent gas that produces energy at its core by nuclear fusion. Most of the visible light in the universe is produced by stars. The Sun is also a star. Stars shine because nuclear fusion occurs in their core. Nuclear fusion changes lighter elements into heavier ones and can release tremendous amounts of energy in the process. Stars are mostly comprised plasma {gas that is electrically charged}. A person with good eyesight can see about 2,000 stars on any given night with naked eye.
Basic Facts About Stars
Asterism and Constellations
A group of stars that make some recognizable shape or pattern is called Asterism. Two famous asterism include the Big Dipper {used to locate north star} and Summer Triangle {three of the most prominent stars in the Northern Hemisphere’s summer night sky}. A constellation is much more complicated asterism, containing more stars or larger areas of the sky. Constellations are mostly named after mythological gods, legendary heroes, creatures, or structures. The constellations encompass the entire celestial sphere and provide a visual reference frame.
Structure in Stars
All stars have layers like a core, radiative zone, convective zone, photosphere, chromosphere, and corona, but in different ratios of thickness depending on the star’s temperature, mass, and age. Very hot, young stars can even be completely radiative and have no convective zone; very cool stars, on the other hand, can be completely convective and have no radiative zone.
The coronae around stars can also vary tremendously, depending on the strengths of the magnetic fields around the stars.
Closest stars to Earth
The Sun is the closest star to Earth. It is average 93 million miles / 149.6 million km away from Earth. The closest star system to Earth is Alpha Centauri. Nearest start in this system is Proxima Centauri, has been measured to be 4.3 light-years away from Earth. The main star in Alpha Centauri is about 4.4 lightyears away.
Proxima centaury is although closest star to Earth after sun, yet it is very faint. The brightest star as seen from Earth is Sirius or Dog Star, which is in a different constellation called Canis Major. It is 8.58 light years away from Earth.
North Star
The North Star is any star near the spot in the sky called the north celestial pole: the place that Earth’s rotational axis is pointing toward.
Right now, and for the past several centuries, Polaris has been very close to the pole, and thus has served as a good north star. Earth’s rotational axis changes its pointing location across the sky over the millennia.
Thousands of years ago, while ancient Egyptian culture thrived, the North Star was a dimmer star called Thuban. Between then and now, there have been stretches of many centuries when there was no useful North Star at all.
South Star
At present , there is no easily visible star near the south celestial pole. There are many asterisms and celestial objects relatively near the pole, so it is possible to triangulate between them and roughly find the location of the south celestial pole.