CHAPTER 1 What Is Outer Space Outer space begins about 60 miles 100 km above the surface of Earth Humans cannot live there There is not enough air to breathe Stars shine in blackness above the atmosphere because there is no air to scatter light and make the sky blue The distances between objects in space are so big that they are not measured in the units of length we use on Earth Distances in outer space are measured in light-years Distance and Light A light-year is the distance that light can travel in one year Light travels at a specific speed of about 186,000 miles 300,000 km per second Doing the math this means that light travels around 5 9 trillion miles 9 5 trillion km in a year The nearest star to Earth is 4 3 light-years away The distances into deep space measure into the billions of light-years atmosphere Outer space begins at the edge of the atmosphere which is the envelope of gases that surrounds Earth 4
Stars and their solar systems group together in space in massive clusters known as galaxies Defining Space Space is full of stars planets asteroids and comets These features are all clumped together in galaxies Our Solar System includes the Sun and the planets that surround it It lies on one of the spiral arms of a galaxy called the Milky Way one of 100 to 200 billion galaxies that exist in the universe The closest galaxy to ours is the Andromeda Galaxy It is 2 3 million light-years away Telescopes are used to help scientists see into space They can see as far as 13 7 billion light-years What lies beyond is a mystery Our universe may not be the only one that exists No one really knows how big space is It is possible that space is much much bigger than we think it is today Future Finds Our understanding of space comes from scientific research and theories As we continue to dig deep into the unknown we find new pieces of information that constantly change challenge and confirm our current body of knowledge The science of outer space is continually evolving Come join the journey 5
Why Explore Outer Space Humans have always explored We want to know what lies beyond the horizon In 1492 exploration took Christopher Columbus on a journey across the sea to land in a continent that no one in Europe knew existed It took astronauts or space travelers to stand on the Moon and look back at Earth in 1969 The drive to explore will push boundaries ever further when it takes astronauts to Mars possibly by 2030 What Is Out There Space scientists are curious by nature They want to seek out and explain the unknown The more they learn the more they realize how much they still do not know Exploration raises new questions It opens new doors and invites us in to a new level of discovery Space exploration helps us better understand not only our own planet and Solar System but also how we fit in the universe It helps answer questions such as how life began on Earth how our Solar System formed and what forces created our universe The benefits of exploring outer space extend beyond one nation to many countries working together with a shared focus and goal The urge to explore space is inspired by the desire to discover not only what lies out among the stars but also what it tells us about ourselves 6
Outer space is full of mysteries such as dark matter which is an invisible form of matter that acts a little like a scaffold to hold the universe together Space mysteries are now being unraveled through exploration In 2017 scientists found seven large exoplanets or planets outside our Solar System They were circling a red star named Trappist-1 It is the first time so many planets have been found circling one star Using Knowledge Exploring outer space means developing new technology that also helps us on Earth Tools designed to detect damage in space rockets do the same thing for bridges and buildings Materials designed to protect against extreme temperatures in space have been used in insoles for mountaineers and distance runners in hot climates Biotechnology was used for purifying water in space The same technology has been adopted on Earth to clean large bodies of water in city lagoons and to treat waste for livestock farms These technologies create new industries and provide new solutions to old problems A rocket carries a telescope into space where it will orbit Earth as it studies the stars YOUR MISSION Trappist-1 is 39 light-years from Earth Astronomers have never seen anything like the dim star with its seven Earth-sized planets Each one of these planets may be capable of supporting life Why do you think this discovery is so significant to humankind 7
