Petersen - Astronomy 101: From the Sun and Moon to Wormholes and Warp Drive, Key Theories, Discoveries, and Facts about the Universe

Welcome to Astronomy 101 and one of the most fascinating sciences in the universe! Whether youre familiar with the night sky and want to learn more about whats out there or just beginning your cosmic journey of understanding, theres something here to teach and inspire you.

Ive been into astronomy since I was a small child when I would go out with my parents to see what was up out there. I grew up wanting to become an astronaut and eventually spent time in college studying a lot of astronomy and planetary science. In the early part of my career I did astronomy research (mostly into comets), and that experience taught me there is nothing quite so fascinating as standing (or sitting) in front of the cosmos, open to new discoveries in space! Nowadays, I spend my time communicating astronomy to the public because I want others to experience the thrill of wonder and discovery that keeps astronomers going. I often give presentations about astronomy on cruise ships and other public places, and the questions people ask about the stars and planets are always fascinating and well thought out. It shows me that the love of the stars is bred into all of usand makes us want to know more about the cosmos.

In Astronomy 101, you get a taste of the cosmos. Astronomy is the scientific study of objects in the universe and the events that shape them. It is one of the oldest sciences and dates back to a point in human history when people first looked up at the sky and began to wonder about what they saw. Astronomy tells how the universe works by looking at what it contains. The cosmos is populated with stars, planets, galaxies, and galaxy clusters, and these are all governed by measurable physical laws and forces.

Each topic in this book gives you a taste of the subject it covers, from planets out to the most distant objects in the universe, introducing you to some of the people who have done astronomy, and venturing into some far out topics, such as extraterrestrial life and the science-fiction universes familiar to TV viewers, moviegoers, video gamers, and readers. Throughout the book, Ive woven in some basic concepts about astronomy and space, such as how orbits work and how to calculate distances in space.

Finally, although this isnt a how to book, in the final chapter, I leave you with a few thoughts about how to go about exploring the universe from your backyard and how we can all work together to mitigate light pollutionthe scourge of all sky gazers.

You can read this book from start to finish, or pick and choose the topics you want to read. Each one gives you a unique insight into the endlessly fascinating universe. And, if what you read spurs you on to more investigation, the reference section at the back points you to further reading.

The astronomer Carl Sagan once said that modern people are descendants of astronomers. Humans have always been sky watchers. Our earliest ancestors connected the motions of the Sun, Moon, and stars to the passage of time and the yearly change of seasons. Eventually, they learned to predict and chart celestial motions. They used that information to create timepieces and calendars. Accurate knowledge of the sky has always helped navigators find their way around, whether across an ocean or in deep space.

Humanitys fascination with the sky may have begun with shepherds, farmers, and navigators using the sky for daily needs, but today that interest has blossomed into a science. Professional astronomers use advanced technology and techniques to measure and chart objects and events very precisely. New discoveries come constantly, adding to a priceless treasury of knowledge about the universe and our place in it. In addition, the tools and technologies of astronomy and space exploration find their way into our technologies. If you fly in a plane, use a smartphone, have surgery, surf the Internet, shop for clothes, eat food, ride in a car, or any of the countless things you do each day, you use technology that in some way derived from astronomy and space science.

In my childhood I was enthralled with a 1927 poem written by American writer Max Ehrmann, Desiderata. My favorite line from it is: You are a child of the universe, no less than the trees and the stars; you have a right to be here. Thats why I draw a link between space and our DNA. All living things are a direct result of the processes that created the cosmos, built the galaxies, created and destroyed stars, and formed planets. We are, in many senses of the term, star stuff. Every atom of every living thing on Earth originated in space, and its poetic and delightful that we evolved to look back out at the light from stars that will eventually contribute their own stuff to create other stars, planets, and maybe even life. Thats why I can say that a love of the stars is woven into our DNA. Whether were professional astronomers or casual sky gazers, thats what draws our attention back to the depths of space. Its where we came from.

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