How Long Will the Earth Exist?

Our fourth science book was published in late 2018. New ones are coming out in May 2019 and November 2019. In this blog we are returning to some of the early columns of Ask Your Science Teacher,  published in 2009. The columns are updated and revised. Many originally ran in The Tomah Journal at the behest of John Kenny, Publisher. We hope you enjoy them, and please give feedback.

Question: How much longer will the Earth exist? 

Answer:  The earth has been around for almost 5 billion years and will continue to be a planet for another 5 billion years. Most scientists believe that our Sun and nine planets were formed at the same time from a huge cloud of dust and gas. The cloud shrank under the pull of its own gravity, forming the Sun and a disk of material that swirled around the sun. Friction caused the disk to collect into huge whirlpools that formed into planets. 

            Earth is a vibrant and dynamic planet. It is always changing, with the surface crust moving around on huge plates. Continents rise and fall. Climate and weather sculpt its features. But the ultimate fate of our Earth is determined by the Sun.

            The Sun is an ordinary star in our Milky Way galaxy that is made up of 100 billion stars. Stars are born, live out their lifetimes, and die. The fate of any star depends on its mass. Massive stars end up as supernovas that may create black holes. Small stars end up as a big piece of cinder. Our Sun is a medium size star.

            The Sun converts hydrogen to helium. This fusion will continue until the hydrogen fuel is all gone. The Sun in now in a stable state, where gravity wants to make it smaller  and radiation wants to push it outward. These two forces are now in balance.

            But look out! Danger is just around the corner! In about 5 billion years from now, the core will contract, get hotter, and the outer layers expand. The Sun will expand to the red giant stage and engulf the inner planets of Mercury, Venus, Earth, and Mars. Earth will have a fiery death. All life will cease on Earth.           

            If you look in the constellation of Orion, you can see the reddish star Betelgeuse that is right above the belt of Orion. Betelgeuse is a sun like ours that is now in the red giant stage. Below the belt of Orion is a hot young blue-white star named Rigel. Rigel is a baby in the evolution of stars.

             Find Orion in the night sky.Orion is a winter constellation, but you will find it in the eastern sky in the early morning hours of July, August and Sept. Look for the three bright stars that make up belt of Orion. Look above the belt for Betelgeuse and below the belt for Rigel.

Follow the three belt stars to the left to find Sirius, the brightest star in the Northern Hemisphere. Sirius is in the constellation of Canis Major, the Big Dog.

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