Hilary Statum - Solar System for Kids: A Junior Scientists Guide to Planets, Dwarf Planets, and Everything Circling Our Sun (Junior Scientists)

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Interior and Designer: Richard Tapp

Art Producer: Tom Hood

Editor: Mary Colgan

Production Manager: Giraud Lorber

Production Editor: Sigi Nacson

Illustrations Kailey Whitman, 2020. Photographs @ Alamy/NASA Photo, .

ISBN: Print 978-1-64611-928-8 | eBook 978-1-64611-929-5

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FOR ANISTON AND HEIDI

Never stop exploring this incredible world weve been blessed with. Much like the universe, my love for you is inconceivable.

Contents

Have you ever looked at the night sky and wondered what is out there? Do you spend time looking for patterns in the stars? Do you wonder if aliens exist? Maybe youd like to be an astronaut or visit another planet someday?

Well, buckle your rocket-ship seat belt and get ready to blast off. We are taking an exciting journey! Space starts about 60 miles above Earth and that is where our adventure begins. The book you hold in your hands will be your guide as you learn some of the secrets of our own solar system and beyond.

We will begin with the big picturethe universe . You will learn about its galaxies, stars, and planets. Once we arrive in our solar system, you will learn ways to study the stars and the Moon from your own backyard. For example, do you know how to tell if you are looking at a planet or a star? The answer is just pages away!

People have always wondered about the universe. In fact, astronomy became the very first science thousands of years ago. Ancient people all over the world watched the sky for changes and recorded them. Then telescopes were invented. They got bigger and better over time. Today, we have telescopes that can see objects billions of light-years away! We have sent astronauts to the Moon and launched space probes that have discovered new stars, moons , and planets. We are still learning more about space today.

Are you ready to begin your adventure? Its time to leave Earth behind!

TAKE A LOOK!

This illustration shows how the artist imagines the Big Bang (see ).

What is the universe? Thats a big question! The universe is everything: the tiniest specks of dust, the largest galaxies, and all the space in between. Trillions of planets, black holes, Earth, and our own solar system drift through what seems like endless empty space.

To give you an idea of how big the universe is, lets look at light. Light travels faster than anything else in our universe. It can travel 186,000 milesabout seven times the distance around Earthin one second! In one hour, light can cross 670 million miles. The universe is so large that light from the farthest parts takes billions of years to reach us!

The observable universe is everything we can see with our eyes and telescopes. Scientists study light coming from an object to measure how fast it is moving toward or away from us. If the object is a galaxy, scientists can use this speed to figure out its distance from Earth. These measurements help scientists understand how large the universe is. Scientists think that the observable universe may reach 46 billion light-years in every direction.

There is much more to the universe than what we can see. It is always expanding, or getting bigger. This makes it difficult for scientists to figure out how large the universe really is, but that doesnt stop them from trying! Some scientists believe that the universe goes on forever!

A Big Bang

Have you ever wondered where the universe came from? It was born so long ago that no one knows for sure how it all happened. Many scientists believe that the universe began with a huge explosion about 13.8 billion years ago. Two events happened at the moment of the explosion. First, the material that would become everything in the universe came into being. Second, the universe began moving outward in all directions. This is called the Big Bang theory. A theory is an explanation for how or why things happen.

Before the Big Bang, the universe was tinier than the point of a needle. Within one second, the universe expanded very quicklyspreading hot, energetic gas billions of miles in every direction. As all of that matter expanded and cooled, some of it began to clump together into enormous gas clouds. When these clouds came together, the first stars were born. It took 300 million years for the first stars to form, and our solar system didnt appear until more than four billion years later!