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Stars and Planets By: Janet Borg Stars and Planets Stars and Planets The sky is everywhere. It begins at your feet, touches the water in the sea, passes over the grass in the fields, surrounds the roofs of houses and buildings, and then goes higher…. Beyond the clouds….. When you look up at the sky, you see some amazing things. In this book you will explore some of the most interesting objects beyond the sky: the Sun, the Moon, the planets, and the stars. The Sun: The Source of Life When you go outside during the day, you encounter the one star in the whole universe that is the closest to us: the Sun. Can you believe that the sun is like the stars in the night sky? If the Sun were as far away as the rest of the stars, it would only be a twinkling dot in the sky. And that wouldn’t be much help to us here on Earth because the sun provides us with light and warmth. Without it, there would be no clouds, no rain, no plants or trees- no possibility of life on earth. Our planet, Earth, circles around the Sun. Earth’s path around the Sun is called its orbit. Earth The Sun is an enormous ball of burning and bubbling gases. It was born about five billion years ago. Now, its life is just about half over. But don’t worry. It will take more than four billion years for the Sun to burn out. Earth receives just the right amount of warmth and light from the Sun. If we were closer to the Sun, everything would burst into flame. If we were farther away, Earth would be too cold to live on. The Sun’s Path Before there were clocks, people used sundials to tell time. A sundial is a pointer attached to a flat surface marked with the hours of the day. The sun casts the shadow of the pointer on the current time. As time passes, the sun appears to move through the sky (it’s actually Earth moving), and the shadow on the sundial moves, too. East In the morning, the Sun comes up. The Sun climbs. It’s noon. Have you noticed In that the sun appears in about the same place every morning? It always rises in the east. Throughout the morning, the Sun moves higher in the sky. Watch the shadows of the trees get smaller. The Sun is at its highest point. This is the time when shadows are the shortest. West Afternoon begins. The Sun starts to sink. As the Sun goes down, shadows grow long again. The shadows stretch in the opposite direction from the way they fell in the morning. Now you know that the Sun rises in the east and sets in the west. So, you can easily find two of the four points on the compass. You can use them to find the other directions. If you face the place where the Sun rises in the morning, you The Sun sets! are looking east. This means that west is At the end of the day, the behind you. South is Sun sets in the western sky on your right. North ablaze as it sinks lower and is one your left. lower in the sky. The Earth spins on its axis like a top. It takes 24 hours –one entire day for it to turn all the way around. At the same time, Earth is also orbiting the Sun. This voyage takes one year to complete. Day and Night Since Earth is spinning, the Sun only shines on one side at a time. On the side of Earth facing the Sun, it is day. It is night on the side that is turned away from the Sun. When you get up in the morning, children far away are getting ready to go home after a long day at school. And somewhere else, other children are still sound asleep. The End of the Day… Little by little, the Sun disappears in the west and night falls. The first thing you may see in the night sky is a twinkling light near the setting Sun. It’s Venus, the planet sometimes called the Evening Star. Venus shines because the clouds that surround it reflect the sunlight like a mirror. …the Beginning of Night Then, as the sky grows ever darker, the real stars appear. At first, you see dozens of stars. And then, hundreds and thousands. A galaxy is a collection of stars. The galaxy that we live in is called the Milky Way. Its billions of stars stretch across the sky in a twirling spiral. Billions of galaxies make up the universe. Soon, the sky is filled with a multitude of stars. Try counting them some evening. Queen of the Night The Moon Some nights, you look at the dark sky and discover a thin sliver of light peeking out from behind a tree or between two buildings. Or, you may look up and see a huge, round, disk lighting up the sky. It’s the Moon! The Moon is the Earth’s satellite. It makes a complete circle around our planet every 28 days. As the Moon orbits the Earth, it also makes the yearly journey around the Sun with us. The Moon doesn’t create its own light like a star does. It merely reflects the Sun’s light. Its different “shapes” are called phases. The phases happen because even though the Sun always shines on one half of the Moon, we see different parts of the lit up half each evening. Think of it as a game of hide-and-seek between the Sun, the Moon and Earth. Mercury The Solar System Venus Earth Mars Jupiter Saturn Uranus Neptune Pluto Planets orbit around stars. The nine planets in our solar system circle our star, the Sun. Our calendars and clocks are based on the movement of the Earth and Moon. One year is measured by the time it takes Earth to travel completely around the Sun. One month is about equal to the time it takes the Moon to orbit Earth. One day is the length of time it takes for Earth to rotate once around on its axis. …To look at the stars always makes me dream. -Vincent van Gogh