George's Cosmic Treasure Hunt (22 page)
Read George's Cosmic Treasure Hunt Online
Authors: Lucy Hawking
“There are too many applications open,” George heard Cosmos say. “Portal will shut down instantly. If this has happened in error, please check the box to send a message to the support unit. Your feedback is important to us.”
The doorway vanished from view, leaving George and Annie by themselves on the mystery planet. Left with nothing to hold on to, George stumbled down the slope toward the black liquid. He pushed off from the ground, just as he had seen Annie do, which sent him upward and across the streamâ¦
“That wind is really strong!” he said, once he'd landed on the other side. All his movements felt as though they were happening in slow motion. “It felt like it was trying to push me over! But it doesn't
seem
to be blowing very hard.”
“Maybe it's a thicker atmosphere than we have at home,” said Annie. “Perhaps that's why it's like being in soup rather than being in air. And there's not much gravity hereâthat's why we're not falling very fast. Oh! What
is
that?” The clouds had just parted to allow them a view of this extraordinary world. On the other side of the lake, they saw a huge mountain with a dip where the peak should have been.
“Wow! That looks like a dead volcano,” said George.
As they gazed at it, they saw the crater at the top spew out great blobs of bluish liquid.
“I don't think it's dead!” shrieked Annie. The thick liquid was moving slowly down through the atmosphere to land on the slopes of the volcano, where it crept along like huge blind sticky earthworms, snaking down the side of the mountain.
“That looks disgusting!” she squeaked. “What is it? And where are we? What planet are we on?”
“You're not on a planet,” Emmett radioed in finally. “You're on Titan, the largest moon of Saturn. You are nearly one billion miles away, near to a cryovolcano, Ganesa Macula, which is currently erupting.”
“Is there any danger from the eruption?” asked George. They could see the strange thick lava creeping down channels carved into the rocky landscape.
“Hard to say,” replied Emmett cheerfully, “given that no life-form we know of has ever landed on Titan before.”
“Thanks a lot, Emmett,” said George darkly.
“But the cryovolcanoes emit waterâeven though it is really cold water. It's mixed with ammonia, which means it can get down to minus one hundred forty-eight degrees Fahrenheit without freezing. So it probably doesn't smell very nice. But that won't bother you, with your space suits on.”
“Emmett, there are lakes here! And rivers!” said Annie. “But they are weird and dark. It doesn't look like water.'
TITAN
Titan is the largest of Saturn's moons and the second largest moon in the Solar System. Only Ganymedeâone of Jupiter's moonsâis bigger.
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Titan was discovered on March 25, 1655, by Dutch astronomer Christiaan Huygens. Huygens was inspired by Galileo's discovery of four moons around Jupiter. The discovery that Saturn had moons in orbit around it provided further proof for astronomers in the seventeenth century that not all objects in the Solar System traveled around the Earth, as was previously thought.
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Saturn was thought to have seven moons, but we now know there are at least sixty moons in orbit around the giant gas planet.
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It takes fifteen days and twenty-two hours for Titan to orbit Saturnâthe same time as it takes for this moon to rotate once on its own axis, which means that a year on Titan is the same length as a day!
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Titan is the only moon we know of in the Solar System that has a dense atmosphere. Before astronomers realized this, Titan itself was thought to be much larger in mass. Its atmosphere is mostly made up of nitrogen with a small amount of methane. Scientists think that it may be similar to the atmosphere of the early Earth and that Titan could have enough material to start the process of life. But this moon is very cold and lacks carbon dioxide, so the chances of life existing there at the moment are slim.
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Titan may show us what conditions on Earth were like in the very distant past and help us understand how life began here.
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Titan is the most distant place on which a space probe has landed. On July 1, 2004, the
Cassini-Huygens
spacecraft reached Saturn. It flew by Titan on October 26, 2004, and the
Huygens
probe detached from the
Cassini
spacecraft and landed on Titan on January 14, 2005.
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Huygens
took photographs of Titan's surface and found that it rains there!
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The probe also observed dry riverbedsâ“traces of once-flowing liquid”âon the surface.
Cassini
imaging later found evidence of hydrocarbons.
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In billions of years' time, when our Sun becomes a red giant, Titan might become warm enough for life to begin!
©
NASA/SCIENCE PHOTO LIBRARY
Artwork of the
Cassini
spacecraft approaching Saturn
