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AnimalsTranscript
00:00You're watching FreeSchool!
00:08It rises in the morning, giving light to the land below it.
00:13It sets in the evening, leaving the world in darkness.
00:18It even provides the heat and energy necessary for life to survive on Earth.
00:24You know what I'm talking about.
00:26The sun.
00:30Because it is so important to us, the sun has been studied and observed since ancient
00:36times.
00:38Astronomers today still study it, and are constantly learning new things about the sun, the center
00:44of the solar system.
00:50The sun is a star, not so different from the stars that can be seen in the night sky.
00:56It may look different, but that is because the sun is many times closer to us than any
01:01other star, which allows us to see how hot and bright it is.
01:08The sun may be close to us compared to other stars, but it is still very far from the Earth,
01:14about 93 million miles or 150 million kilometers away.
01:21Although the sun is so far away, it only takes sunlight about 8 minutes to reach the Earth
01:26because light travels so fast.
01:31Because the sun is so far away, however, it seems much smaller than it really is, more
01:36than 100 times the width of the Earth.
01:40The sun is so large that if it were empty, more than a million Earths could fit inside.
01:45The sun is the largest object in the solar system.
01:53In fact, if you collected everything in the solar system including the sun, the planets
01:59and dwarf planets, comets, asteroids and moons, the sun would account for more than 99% of
02:06it, with everything else adding up to less than 1% of the solar system.
02:13As far as stars go, however, the sun is average, or even small in size.
02:18It is called a yellow dwarf, and there are billions of stars like it in the Milky Way.
02:29Like other stars, the sun is made of gases, mostly hydrogen, with a little helium, and only
02:35traces of other elements.
02:39These gases are held together by the sun's gravity, which creates such intense heat and
02:44pressure that it causes nuclear fusion, a process in which hydrogen atoms fuse to create
02:51helium, at its core.
02:55The sun's core is about 27 million degrees Fahrenheit, or 15 million degrees Celsius.
03:03By the time heat from the sun's core reaches its surface, temperatures have dropped considerably.
03:09The surface of the sun is only about 10,000 degrees Fahrenheit, or 5,500 degrees Celsius.
03:21Unlike the earth, the sun does not have a solid surface.
03:25You may be surprised to learn that the sun's gassy surface is not calm and quiet.
03:30Instead, the sun is constantly moving and changing, with sunspots, or dark patches of cooler temperatures,
03:40and solar flares, or eruptions of high energy radiation, frequently marking its surface.
03:48All of the planets in the solar system, including the earth, orbit around the sun.
03:56In turn, the solar system orbits around the center of the galaxy in which we live, the Milky
04:01Way.
04:04It only takes the earth one year to complete an orbit around the sun, but scientists estimate
04:10that it will take the sun about 230 million years to complete an orbit of the galaxy.
04:19Since ancient times, humans have understood how important the sun is for life on earth.
04:25Without the energy provided by the sun's radiation, the earth would be dark, cold, and uninhabitable.
04:34Although it has been studied for thousands of years, there is still much to learn about
04:38the sun.
04:40I hope you enjoyed learning about the sun, the center of our solar system.