What is extinction? Why do some kinds of life become extinct? Extinction happens when an animal or plant no longer exists on Earth. Animals and plants die off completely when the conditions they need to live are no longer met by their environment. When scientists and governments become worried that an animal or plant will become extinct, they place the animal or plant on an endangered species list. Endangered species are often given special protection, to help them gain strength in numbers and continue to exist on our planet.
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What is the sun? The sun is a star around which the planet earth orbits. It is 93 million miles away, but its light reaches us within 8 minutes.
Like other stars, the sun is a ball of super-heated gases held together by gravity. The sun contains over two-thirds of the elements that make up all of the things on earth. However, it is mostly made up of a common gas called hydrogen. Hydrogen is so common it is one of two elements that make up water (air is made up of other gases: mostly nitrogen mixed with some oxygen, the other element that with hydrogen makes up water).
The sun is similar to a big factory, one that converts hydrogen to helium. When the sun converts hydrogen to helium (the same kind of helium that fills up your lighter-than air balloons), it generates energy: heat and light. The center, or core, of the sun is very hot, so hot it causes the star to glow. The light and heat the sun gives off enable life to exist on earth.
Stars come in different sizes, temperatures, and colors. Our sun is a yellow star of average temperature and size. Even though our sun isn't big when compared to the billions of other stars in the universe, or even the millions of other stars in our galaxy, the Milky Way, the sun could hold 1.3 million planet earths.