Edwina

​​​​ =***STARS*** = What are stars? Stars are massive balls of plasma that are held together by gravity.

Facts about stars: Believe it or not, there are more stars than there are grains of sand on Earth. There are around 250 billion stars in our galaxy. When stars have too much gravity, this causes them to get smaller and smaller and they eventually turn into black holes. There are different coloured stars. The ones that give off a blue light are the hotter ones and the redder ones are cooler. The closest star to Earth is The Sun.

The Milky Way: The Milky Way is a cluster of stars (believed to be about 200-400 billion stars) which is held together by gravity in a spiral shape. In clear conditions, The Milky Way is visable to the naked eye and looks like a band of faint light across the night sky. It is believed that the name 'Milky Way' came from it's appearance, as if it is a spilled puddle of milk. The Milky Way was discovered in around the 1750's when observers realised that it was actually made of clusters of millions of stars. The oldest star in the Milky Way is believed to be as old as 13.2 billion years old which is nearly as old as the Universe itself which is estimated to be around 13.7 billion years old.

Types of stars: There are seven main types of stars in the universe with them being classified by their temperature and the elements they absorb. These stars, in order of decreasing temperature, are the main ones: O, B, A, F, G, K and M. O and B stars are really bright but uncommon and M stars are common but they are dim.

Dwarf Stars- 'Dwarf Star' is strangely enough, a term used for stars that is of normal size for its' mass. Our sun is a dwarf star and is classified as a yellow dwarf. Dwarf stars can be up to 20 times bigger and 20,000 times brighter than our sun. Dwarf stars lie on the main sequence and are in the process of converting hydrogen to helium.



Yellow Dwarf Stars- Yellow dwarf stars are small, main sequence stars, like our sun. They are classified as type G stars and about one in thirteen stars in the main sequence are yellow dwarf stars. Yellow Dwarfs have a medium temperature and this is why they are yellow. Thier fuel burns faster than the Red dwarf because of their temperature, so they will only live for about 10 billion years. Near the end of their lives, Yellow Dwarfs expand and when the Sun does this, it will cause the Earth to be engulfed but this won't happen until about another 5 billion years so we have nothing to worry about.



Red Dwarf Stars- Red dwarf stars are the most common type of star. They are small, very faint, cool, main sequence stars. Because of their small size, these stars burn fuel very slowly and will live for up to trillions of years. The reason why they aren't as hot as other types of stars, is because of how slow their fuel burns. You don't really see that many Red Dwarfs in the night sky because they are so small and don't emit as much light as other stars.

** Giant and Super Giant Stars **



Red Giant Stars- A Red Giant star is a star in the last phase of its life. After a few more million years, a Red Giant star will turn into a White Dwarf and then that's the end of the stars' life. The appearance of a Red giant star is a yellow, orange or red colour.



Blue Giant Stars- Blue Giants are extremely hot, very large and also compact. As blue giants get older, they expand and get cooler, eventually turning into Red Giant stars. Blue Giants give off the blue colour because of how hot they are. They burn their fuel very quickly because of their temperature and only last around ten thousand to one hundred thousand years. Because they are so bright, Blue Giants are what most of the stars we see at night are.



Super Giants- Super Giants are massive stars even as big as our whole solar system! The only difference between Giant Stars and Super Giants is their sizes. They are the largest known type of star and are very rare. When they die, they become black holes. If the Sun was a Super Giant, it would nearly be able to reach Uranus.

Faint/Virtually Dead Stars



White Dwarf Stars- White Dwarf stars are what's left of stars after they have burnt all their nuclear fuel. They are a small very hot star made of mostly carbon and will eventually lose all of their heat and turn into a Black Dwarf. They are about half as big as the Sun but only a little bigger than our Earth.



Brown Dwarf Stars- Brown Dwarf Stars, also known as 'failed stars', are larger than planets but do not have sufficient mass to convert hydrogen to helium. Constellations! Here are the twelve main constellations of the Zodiac that you've probably heard of. These are also known as 'Star Signs'.


 * 1) Aquarius
 * 2) Aries
 * 3) Cancer
 * 4) Capricorn
 * 5) Gemini
 * 6) Leo
 * 7) Libra
 * 8) Pisces
 * 9) Saggittarius
 * 10) Scorpio
 * 11) Taurus
 * 12) Virgo

Aquarius is the water bearer, Aries is the ram, Cancer is the crab, Capricorn is the goat, Gemini is the twins, Leo is the lion, Libra is the scales, Pisces is the fish, Saggitarius is the archer, Scorpio is the scorpian. Taurus is the bull and Virgo is the virgin.



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I hope all of this information about stars has been very useful to you :) - E d w i n a