TITAN


Saturn’s largest moon is sometimes called an “alien Earth.” Titan is rocky. It has rivers and lakes. Clouds fill the sky. Sand dunes cover much of the moon. Yet while these things may look familiar, they’re not what they seem. T e rocks are made of icy chemicals. T e


rivers and lakes are filled with liquid methane. T e clouds are orange. T e sand dunes may be oddest of all. T eir “sand” isn’t sand at all. It’s chemical particles that rain from the clouds. Even so, Titan’s dunes look a lot like the


red sand dunes in Kalahari Desert in Africa. To form these Earth dunes, winds blow sand. It piles up. Some forms dunes in the shape of moon-like crescents. T eir curved ends point to the way the wind blew. Other dunes are long and thin. T ey were formed by winds blowing parallel to them. Titan’s whipping winds sweep its strange


sand into dunes, too. Just like on Earth, we can use them to tell which way the winds blow on Titan. We once thought Titan’s winds blew east to west. T e shape of its dunes tells us a diff erent story. T is moon’s strongest winds blow west to east.


Dealing With Data I may never leave Earth. Yet with telescopes, spacecraſt , and rovers, I can explore our solar system. T e cameras and other tools they carry make me feel like I’m on these planets and moons. More importantly, they let scientists like me collect all sorts of data from afar. T en comes the fun part—figuring out what


the data mean. T at’s where Earth comes in handy. By comparing space data to data from look-alikes on Earth, we can reach conclusions about what we see in space. For example, we can figure out how a place in space formed. We can learn if places in space are just like Earth.


This illustration shows dunes formed by winds on Saturn’s biggest moon, Titan.


Ripples in the sand and the shape of this dune in Africa can tell us which way the wind blows.


data: facts and information used to calculate and analyze something, such as the size and composition of an object in space


fault: a fracture, or crack, in the crust of a planet or moon


geology: the science that deals with Earth’s physical structure, its history, and the processes that act on it


landform: a natural feature such as a mountain or delta on Earth’s surface


sediment: particles of soil or rock that have been moved and deposited by water, wind, or ice


SEPTEMBER 2014 17


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