George's Cosmic Treasure Hunt Read Online Free PDF

atmospheric pressure—which means the weight of the air above you in the atmosphere—must have been higher because we can see what appear to be dried-up channels and lakes. Liquid water cannot exist on Mars now, as it would just evaporate.
    However, there is lots of water in the form of ice at the two poles. If we went to live on Mars, we could use this. We could also use the minerals and metals that volcanoes have brought to the surface.
    So the Moon and Mars might be quite good for us. But where else could we go in the Solar System? Mercury and Venus are way too hot, while Jupiter and Saturn are gas giants, with no solid surface.
    We could try the moons of Mars, but they are very small. Some of the moons of Jupiter and Saturn might be better. Titan, a moon of Saturn, is larger and more massive than our Moon, and has a dense atmosphere. The Cassini-Huygens mission of NASA and ESA, the European Space Agency, has landed a probe on Titan, which sent back pictures of the surface. However, it is very cold, being so far from the Sun, and I wouldn’t like to live next to a lake of liquid methane.
    What about beyond our Solar System? From looking across the Universe, we know that quite a few stars have planets in orbit around them. Until recently we could see only giant planets the size ofJupiter or Saturn. But now we are starting to spot smaller Earth-like planets, too. Some of these will lie in the Goldilocks Zone, where their distances from the home star is in the right range for liquid water to exist on their surfaces. There are maybe a thousand stars within ten light-years of Earth. If 1% of these have an Earth-size planet in the Goldilocks Zone, we have ten candidate new worlds.
    At the moment we can’t travel very far across the Universe. In fact, we can’t even imagine how we might be able to cover such huge distances. But that’s what we should be aiming to do in the future, over the next two hundred to five hundred years. The human race has existed as a separate species for about two million years. Civilization began about ten thousand years ago, and the rate of development has been steadily increasing. We have now reached the stage where we can boldly go where no one has gone before. And who knows what we will find and who we will meet?
    Good luck on all your cosmic journeys, and I hope you find this book useful.
    Interstellar best wishes,
    Â 
    Eric

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Chapter 3
    F inally, the day came when the doors slammed on the last vanload of Eric, Annie, and Susan’s belongings, and they were standing in the street, saying goodbye to George and his parents.
    â€œDon’t worry!” said George’s dad. “I’ll keep an eye on the house for you. Might tidy up the garden a bit.” He gave Eric a firm handshake, which made the scientist turn rather pale and rub his hand afterward.
    George’s mom hugged Annie. “Who’s going to kick a ball over my fence now?” she said. “My vegetable patch is going to find life very quiet.”
    Annie whispered something in her ear. Daisy smiled. “Of course you can.” She turned to George. “Annie would like to say good-bye to Freddy,” she told him.
    George nodded, not wanting to speak, in case his voice wobbled. In silence, the two of them went through George’s house and out into the backyard.
    â€œGood-bye, Freddy,” cooed Annie, leaning over the pigsty. “I’m going to miss you so much!”

    George took a deep breath. “Freddy’s going to miss you too,” he said, his voice squeaking from the effort of holding back the tears. “He really likes you,” he added. “He’s had a really great time since you’ve been here. It isn’t going to be the same once you’re gone.”
    â€œI’ve had a great time as well,” said Annie sadly.
    â€œFreddy hopes you don’t find another pig in America that you like as much as him,” said