4 Space is the most extreme and hostile environment to survive in There is no air for humans to breathe and no supply of food or shelter Yet Space has always fascinated people For hundreds of years astronomers have peered at the night sky through telescopes observing and trying to make sense of the Universe Wide-Open Space Space begins 62 miles 100 km above the ground where the atmosphere is too thin for aircraft to fly To reach Space a spacecraft has to travel fast enough to overcome the force of gravity The first rockets powerful enough to do this were only developed about 60 years ago WORKING IN SPACE Astronauts practice everything they do in Space in labs on Earth first in order to anticipate and avoid possible problems Modern telescopes take incredible photos of stars and galaxies trillions of miles away This photo shows a star dying
5 Humans in Space Between 1968 and 1972 seven spacecraft and 24 astronauts made the nearly 250,000-mile 400,000-km journey to the Moon Since then astronauts have been confined to orbiting Earth At present the only habitat for humans in Space is the International Space Station ISS which orbits about 220 miles 354 km above Earth Exploring Space Scientists study Space to try to understand how the Universe began and how it works They are searching for traces of life on other planets and for minerals that could be useful to humans on Earth Scientists also use satellites in Space to study events on Earth such as floods and forest fires rising sea levels and air pollution In this book we will look at how space scientists carry out their research what they do with the results and some of the discoveries they have made This close-up of Saturn and its rings was taken by an unmanned spacecraft called Cassini DANGER Lack of air to breathe is not the only hazard facing astronauts in Space The temperature changes from 212 F 100 C in the sunlight to extremely cold 148 F 100 C in the shadows In addition lethal amounts of radiation from solar particles and cosmic rays can strike with little or no warning
6 As telescopes become increasingly sensitive astronomers are obtaining more and more information about the Universe They have seen the birth and death of stars and extraordinary phenomena including supernovas massive exploding stars white dwarfs and distant galaxies Vast Distances The Universe is unimaginably huge Gaia a space observatory see page 19 is mapping a billion stars but they are just 1 percent of the total stars in our galaxy the Milky Way The Milky Way is one galaxy out of hundreds of billions The distances between galaxies are so vast they cannot be measured in miles or kilometers Instead they are measured in light-years A light year is the distance traveled by light in one year about 6 trillion miles nearly 10 trillion km WHAT’S OUT THERE An artist used information collected by a spacecraft to create this picture of a 13-billion-year-old black hole
7 Looking Back in Time Because distances in Space are so immense astronomers are looking back in time as well as over distance For example if they observe a supernova 13,000 light-years away it took 13,000 years for the light of that supernova explosion to reach them This means the explosion happened 13,000 years ago Telescopes that orbit Earth in Space take very clear and detailed photos These two distant galaxies are called Arp 273 DANGER Astronomers think there is a black hole at the center of every galaxy A black hole is not actually a hole it forms when a megastar collapses into a tiny space Its gravity is so immense that it pulls in stars planets and everything around it Nothing can escape not even light Scientists can detect a black hole from the cloud of gas that glows brighter and brighter as it spirals into the hole The Whirlpool Galaxy is one of the brightest galaxies in the sky Its stars form a spiral around the centre
