Discovering Planets & Moons

Discovering Planets & Moons — page 1 — The Earth and Sun as seen from space 4

Discovering Planets & Moons — page 2 — INTRODUCTION It’s hard to imagine what is beyond our planet but in reality the universe is much bigger than life on Earth Looking up at the sky can tell us a lot about the universe and ancient astronomers did just that as they started exploring space During the day the Sun and clouds show just a hint of what’s beyond Earth but at night the Moon and stars show us that there is far more out there than first meets the eye The invention of the telescope in the early 1600s gave us a new way to look at the sky Astronomers could see much farther into space far beyond what merely their eyes could see They mapped and calculated and spent years trying to learn more about space In the 1960s we made another huge stride in space exploration by sending humans into outer space To investigate what lies beyond our world humans have studied the Moon and stars from spaceships walked on the Moon and even lived in outer space in the International Space Station page 73 WHAT IS IN SPACE Once you leave planet Earth there is no breathable air in the atmosphere That’s why astronauts have to wear large oxygen tanks when they are outside of their spaceship Outer space is black but that doesn’t mean it’s empty Gas dust and matter make up most of space but there are also objects like planets page 9 moons page 25 galaxies page 43 stars page 51 and dwarf planets page 61 There are also smaller objects like meteors asteroids and comets that move throughout space Two interesting elements of space are supernovas and black holes When a star runs out of fuel it explodes this explosion forms a supernova Black holes are areas where nothing not even light can escape from These mysteries of space are hard to understand because scientists have not been able to explore them Objects in space are not stationary most travel in an orbit around another object Sometimes these moving objects collide It’s impossible for us to measure the size and age of space Our explorations have led us to find objects that are billions of years old Distance in space is measured in light years or the distance that light travels in one year Despite all of our explorations we have not yet found evidence of other forms of life in space 5

Discovering Planets & Moons — page 3 — WHY DO WE EXPLORE SPACE Humans are explorers by nature and that desire to explore extends far beyond the boundaries of Earth But our own curiosity is not the only reason to care about what happens in space Our lives are ruled by the Sun and Moon the Sun’s rays heat our planet the Moon’s gravity controls the ocean’s tides and together they set our days and nights Also important is the fact that other objects in space are not stationary and are constantly moving around our planet understanding the objects in the universe and their location helps us to better understand our own planet Although we have not yet found evidence of life on other planets scientists hope to determine if there are other planets that could support life This doesn’t just mean looking for aliens It means that scientists are looking for planets with appropriate temperatures a stable atmosphere and sufficient water together these three things would allow plants or people to grow and thrive As of now humans could not live on any other planet but scientists are always looking to see whether it would be possible Space is made up of matter and elements many of which are also present on Earth In our own ever changing climate however it is important for us to understand the different matter and forces in the universe that could have the potential to give us new forms of energy Our Sun center and its solar system from left to right Pluto a dwarf planet Neptune Uranus Saturn Jupiter Mars Earth Venus and Mercury 6

Discovering Planets & Moons — page 4

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