What is a star?

 

Close your eyes and imagine you are standing in a wide open field. In the field you see a gigantic white rocket reaching far up into the sky. As you walk up to the rocket, the door opens and you climb inside and find a seat and buckle up. Next you hear the countdown – 5, 4, 3, 2, 1. Suddenly the rocket rumbles as it lifts of the ground and shoots through the sky, past the clouds, and up, up, up into space. When you look out the window you see the round blue ball of earth far below.

The rocket is going faster and faster. You zoom past the moon as the rocket picks up speed. Soon the other planets of our solar system pass you by. You look back and notice the earth has grown smaller and smaller until it has disappeared from view. Then suddenly you are traveling at the speed of light, and before long you have left the solar system and are deep into outer space. All is black. You travel further and further until suddenly you look out your window and see a beautiful cloud of dust and gas all swirling together. You have arrived at the place where stars are born. It is called a stellar nursery, which means a star birthing place.

Stars are sort of like people in that they are born, and they grow until they are bigger, and then eventually get old and die. But unlike people stars live for millions or even trillions of years. Our own sun is a star, it’s just a lot closer than the stars we see twinkling in the sky at night that appear so small.

For millions of years clouds of dust and gas in space swirl around each other in what is called a nebula. Over time these clouds slowly group together into clumps that eventually become baby stars — or protostars. Some stars grow bigger and bigger until they become as large as our own sun. And often they have their very own planets, just like our sun has its own planets. These stars become very hot  and bright, which is why when you look up at the sky at night you can see them even though they are sooo far away. To travel to many of these stars would take thousands of years.

The reason we know a lot about how stars are born is because of a space telescope. A space telescope is a telescope that is launched into space and can see better because it is above the earth. The Herschel Space Observatory was built by the European Space Agency and watched where stars were born for 4 years. Because of the hard work of the engineers and astronomers working on this space telescope, we know a lot more about the life of stars.

After changing from clouds of gas and dust many of these baby stars eventually become “main sequence” stars, then sub-giant stars and then red giant stars. Many of these very large stars are thousands of times bigger than our own sun. And our own sun is very, very big.

After millions of years even stars grow old and die. Eventually they begin to collapse in on themselves and then suddenly explode in what is called a supernova. During a supernova they shoot gas and dust for millions of miles around them. Supernovas happen in the universe all the time but often it’s hard for us to see them happening because there are so many stars and they are so far away. The people who study stars are called astronomers. Most astronomers thought the only way to see supernovae would be to use a large telescope run by many astronomers. In Australia there was an amateur astronomer named Robert Evans. He had a normal job during the day, but at night his favorite thing to do was to go on his back porch and use his little telescope to watch the stars. Robert was interested in supernovas, when stars explode, but decided he didn’t need all of the big telescopes to see them. So he started watching for supernovas on his own. For many nights Robert didn’t see anything. But he kept watching and kept waiting, until he saw his first supernova. He was so excited. Over the years Robert has seen 42 supernovae! Which is an amazing achievement. Because Robert is very patient and very diligent he has been able to see when these gigantic stars explode all the way across the galaxy.

When we look out in the night sky we see many stars, but they are very far away. After the sun, the closest star is called Alpha Centauri. Alpha Centauri is 25 trillion miles away! This gives you a little bit of an idea of how large our galaxy is.

Stars like our sun are very important because they are like huge factories which give off energy and heat. They send this energy in the form of waves that travel all the way across space to Earth. There are many reasons our sun is important. First off, without it would always be night. If it was always night, it would be very hard to see! Also, trees would never grow, because trees need the sun’s energy to grow. Without trees and other plants we wouldn’t have oxygen to breath and animals wouldn’t have food. And without animals and plants we wouldn’t be able to eat either. We would all be in very big trouble! Also, the earth would become very very cold and everything would freeze. Even on hot days, we should be very grateful we have a sun that keeps planet Earth running smoothly.

Next time when you go outside and feel the warm sun on your skin, think about how the sun rays travelled 100 million miles to to make you warm. That’s pretty amazing that an object sooo far away can make its way all the way to you and keep you warm and keep us all alive.

When we learn about how stars and our own sun it makes us grateful for nature and the world around us. And when we understand how important they are it reminds us to respect and take care of what we have.

Tonight think of some ways you can better take care of the Earth, whether it means picking up trash outside or not wasting water or planting flowers or a tree. There are many things around us in nature that we can be curious about and appreciate if we just take the time to notice them.

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