Blue Lantern Studio/Corbis. 136 (b) Images.com/Corbis. 157 (c) Photo courtesy of Joel Gardner/Flat Out Films. 158 (c) PhotoObjects.net/Jupiterimages. 161 (b) The Bridgeman Art Library/Getty Images. 169 (r) Superstudio/Getty Images. 171 (t) Peter Turnley/Corbis. 172 (b) Bettmann/Corbis. (bg) Rob Bartee/Alamy Images. 173 (c) Bettmann/Corbis. 174 (b) Rogelio V. Solis/AP Photo. 175 (t) Wally McNamee/Corbis. 176 (bc) Ace Stock Limited/Alamy Images. (bl) Danny Lyon/Magnum Photos. (ml) David Young-Wolff/PhotoEdit. (tc) James L. Amos/National Geographic Image Collection. (tl) James P. Blair/National Geographic Image Collection. (tr) Reuters/Corbis. 178 (l) Carl Iwasaki/Time Life Pictures/Getty Images. 178-179 (LesOp) Spider Martin. 180 (c) Library of Congress, Prints & Photographs Division, FSA/OWI Collection, [LCDIG-fsa-8a03228]. 181 (c) Hulton Archive/Getty Images. 182 (b) Bettmann/Corbis. 183 (r) Carl Iwasaki/Time Life Pictures/Getty Images. 184 (r) Carl Iwasaki/Time & Life Pictures/Getty Images. 185 (b) Copyright 2003. The University of Michigan Photo Services. All Rights Reserved. (t) Carl Iwasaki/Time Life Pictures/Getty Images. 186 (t) Corbis. 187 (r) Bettmann/Corbis. 188 (c) Flip Schulke/Corbis. 189 (r) Gene Herrick/AP Images. 190 (tl) Time Life Pictures/Time Magazine, Copyright Time Inc./Getty Images. 190-191 (tr) Grey Villet/Time Life Pictures/Getty Images. 192-193 (t) Francis Miller/Time Life Pictures/Getty Images. 194 (bg) Paul Edmondson/Jupiterimages. 195 (t) AP Photo/Gene Herrick. 200 (b) Bettmann/Corbis. 201 (r) Bettmann/Corbis. 202 (b) Time & Life Pictures/Getty Images. 204 (bc) Alison Wright/National Geographic Image Collection. (bl) Stephen St. John/National Geographic Image Collection. (mc) William Lovelace/Express/Getty Images. (ml) Dalmas/SIPA Press. (mr) Mario Tama/Getty Images. (tc) The Granger Collection, New York. (tl) Rebecca Cook/Reuters/Landov. (tr) allOver photography/Alamy Images. 209 (b) Fox Photos/Getty Images. 212 (t) Donald Uhrbrock/Time Life Pictures/Getty Images. 214 (b) Ernst Haas/Getty Images. (t) Candlewick Press. 217 (b) Julian Wasser/Time Life Pictures/Getty Images. 220 (b) Dana White/PhotoEdit. (bg) Nicemonkey/Alamy Images. 221 (c) Tony Freeman/PhotoEdit. 222 (b) David Young-Wolff/PhotoEdit. 224 (bc) Jim Wright/Star Ledger/Corbis. (bl) Chuck Savage/Corbis. (mc) Joel Sartore/National Geographic Image Collection. (ml) Jeff Greenberg/Alamy. (mr) Annie Griffiths Belt/National Geographic Image Collection. (tc) Robert Sciarrino/Star Ledger/Corbis. (tl) Bobby Model/National Geographic Image Collection. (tr) Lee Celano/AP Images. 228 (t) Bruce Kluckhohn. 229 (c) Bruce Kluckhohn. 230 (t) David L. Moore/Alamy Images. 232 (l) Steve Miller/AP Images. 233 (r) Corbis/Jupiterimages. 234 (c) Boundless Playgrounds. 244 (l) NASA/JPL/PIRL/UofArizone/Michael/Peter Arnold, Inc. (r) NASA/National Geographic Image Collection. 245 (l) Myron Jay Dorf/Corbis. (r) Stocktrek Images/Getty Images. 247 (t) Daniel L. Geiger/SNAP/Alamy Images. 248 (b) Tim Kiusalaas/Corbis. (bq) The Stocktrek Corp/Brand X/Corbis. 249 (l) Kayte M. Deioma/PhotoEdit. (r) Paul Thompson/Eye Ubiquitous/Corbis. 250 (b) James L. Stanfield/National Geographic Image Collection. 252 (bc) Chris Cheadle/Alamy Images. (bl) JTB Photo Communications, Inc./Alamy Images. (mc) Dustin Steller/Design Pics/Corbis. (ml) Quilla Ulmer/Jim Reed/Photo Researchers, Inc.. (mr) Tim Kiusalaas/Corbis. (tc) Riser/Glen Allison/Getty Images. (tl) Corbis. (tr) Eddie Hironaka/Image Bank/Getty Images. 254-255 (LesOp) NASA/JPL/Image Envision. 256 (c) NASA-JPL - Mars Pathfinder/digital version by Science Faction/Getty Images. (t) ESA/K. Horgan/Stone/Getty Images. 257 (ml, mc, bl, bc) Scott Tysick/Masterfile. (tr) NASA/Roger Ressmeyer/Corbis. 258 (ml, mc, bl, bc) Scott Tysick/Masterfile. 259 (bl) A-JPL-Caltech -Cassini/digital version by Science Faction/Getty Images. (br) Photos.com/Jupiterimages. (tl) LASP/NASA/Handout/Reuters/Corbis. (tr) NASA/Time Life Pictures/Getty Images. 260 (b) StockTrek/Photodisc/Getty Images. (t) Photodisc/SuperStock. 261 (r) NASA/Getty Images. 262 (b) Reuters/Corbis. (t) World Perspectives/Stone/Getty Images. 263 (r) Images.com/Corbis. 268 (b) Stock Illustration Source/Getty Images. 270 (bl) Michael Lewis/Corbis. (br) Anthony West/Corbis. 270 (bg) NASA, ESA and the Hubble Heritage Team (STScI/AURA). 271 (r) NASA/Roger Ressmeyer/Corbis. 272 (b) Rex Stucky/National Geographic Image Collection. 274 (bc) NASA/ESA/The Hubble Heritage Team (STScI/AURA)/P. Knezek (WIYN)/Space Telescope Science. Institute. (bl) Transtock. (mc) Vince Streano/Corbis. (ml) Joe McBride/Stone/Getty Images. (mr) Creatas Images/PunchStock. (tc) Lester V. Bergman/Corbis. (tl) NASA Human Space Flight Gallery. (tr) Visuals Unlimited/Corbis. 276 (tl) image100/Corbis. (b1) NASA Human Space Flight Gallery. 276-277 (LesOp) NASA/Roger Ressmeyer/Corbis. 278 (l) Hubble Image: NASA and ESA; Acknowledgment: K.D. Kuntz (GSFC), F. Bresolin (University of Hawaii), J. Trauger (JPL), J. Mould (NOAO), and Y.-H. Chu (University of Illinois, Urbana); CFHT Image: Canada-France-Hawaii Telescope/J.C. Cuillandre/Coelum; NOAO Image: G. Jacoby, B. Bohannan, M. Hanna/NOAO/AURA/NSF. 279 (r) NASA Human Space Flight Gallery. 280 (r) NASA Human Space Flight Gallery. 281 (r) NASA Human Space Flight Gallery. 282 (r) NASA Human Space Flight Gallery. 283 (bg) John Marshall Mantel/Sipa Press/NewsCom. 284 (t) NAS/Roger Ressmeyer/Corbis. 285 (l) Larry Dale Gordon/The Image Bank/Getty Images. (r) NASA Human Space Flight Gallery. 286 (r) NASA Human Space Flight Gallery. 287 (b) NASA Human Space Flight Gallery. (t) image100/Corbis. 288 (r) NASA Human Space Flight Gallery. 292 (b) image100/Corbis. 294 (bl) Atlantide Phototravel/Corbis. (br) Gabe Palmer/Alamy Images. 296 (b) Corbis. 298 (bc) Somos Images LLC/Alamy Images. (bl) Image Source/Corbis. (mc) ColorBlind Images/Iconica/Getty Images. (ml) Darren Robb/The Image Bank/Getty Images. (mr) BrandX/Jupiterimages/Alamy Images. (tc) Will & Deni McIntyre/Corbis. (tl) bilderlounge/Corbis. (tr) Kevin Dodge/Corbis. 301 (c) Lou Wall/Corbis. 302 (r) Images.com/Corbis. 307 (r) Archivo Iconografico, S.A./Corbis. 311 (c) Carmen T. Bernier-Grand. 314 (b) Comstock/Corbis. 322 (l) Paul A. Souders/Corbis. (r) Craig Tuttle/Corbis. 323 (c) National Geographic Digital Media. (r) Huetter, C./Arco Images/Peter Arnold, Inc. (b) George Grall/National Geographic Image Collection. 324 (t) Klaus Nigge/National Geographic Image Collection. 325 (t) Michael Melford/National Geographic Image Collection. (br) National Geographic Digital Media. 327 (t) Peter Arnold, Inc./Alamy Images. (b) Jupiterimages/Botanica/Jupiter Images. 328 (b) DLILLC/Corbis. (bg) Robert Llewellyn/zefa/Corbis. 329 (t) Tom Brakefield/Photodisc/Getty Images. (b) Nick Greaves/Alamy Images. (bg) Penny Tweedie/Corbis. 330 (b) Joel Sartore/National Geographic Image Collection. 332 (bc) Thomas Mangelsen/Minden Pictures. (bl) Karen Kasmauski/National Geographic Image Collection. (mc) Dennis MacDonald/Alamy Images. (ml) Charles O’Rear/Corbis. (ml) F Hart/The Bridgeman Art Library/Getty Images. (tc) Joel Sartore/National Geographic Image Collection. (tl) Comstock Images/PunchStock. (tl) Riser/Ableimages/Getty Images. 334-335 (LesOp) Michele Westmorland/Corbis. 336-337 (l) Jeff Greenberg/PhotoEdit. 337 (r) Skip Brown/National Geographic/Getty Images. 338 (l) Philip Schermeister/National Geographic/Getty Images. 341 (bg) Stuart Westmorland/Getty Images. (br) C. & D. Frith/Frithfoto/Bruce Coleman Inc.. (mr) Robert P. Carr/Bruce Coleman Inc.. (tr) Nicholas Parfitt/Getty Images. 342 (b) Tom Brakefield/Stockbyte/Getty Images. 343 (bg) Liu Jin/AFP/Getty Images. (bl) Christopher Talbot Frank/Photex/zefa/Corbis. (ml) Joel Sartore/National Geographic/Getty Images. (tl) Chris Johns/National Geographic Image Collection. 349 (b) Brian J. Skerry/National Geographic Image Collection. 350 (b) Joe McDonald/Corbis. (bg) Ralph A. Clevenger/Corbis. 351 (tr) Tom Brakefield/Corbis. (br) DK Limited/Corbis. 352 (b) Chris Johns/National Geographic Image Collection. 354 (bc) Michael S. Quinton/National Geographic Image Collection. (bl) Dorling Kindersley/Mike Downing/Getty Images. (mc) Raymond Gehman/National Geographic Image Collection. (ml) Blend/PunchStock. (mr) Tim Laman/National Geographic Image Collection. (tc) David R. Frazier Photolibrary, Inc./Alamy Images. (tl) image100/Corbis. (tr) Paul Nicklen/National Geographic Image Collection. 356-357 (LesOp) Steve Bloom Images/Alamy. 358 (c) Layne Kennedy/Corbis. 359 (t) Dr. Dale Miquelle/Wildlife Conservation Society. 360-361 (b) Ilya Naymushin/Reuters/Landov. 361 (t) Dr. Maurice G. Hornocker/National Geographic Image Collection. 362 (t) Pavel Filatov/Alamy. 364 (bc) China Photos/Getty Images. (bl) Purestock/Getty Images. (br) Michael Nichols/National Geographic Image Collection. (mc) Michael K. Nichols/National Geographic/Getty Images. (mr) Jimin Lai/AFP/Getty Images. (t) Martin Harvey/Alamy. 366 (t) Layne Kennedy/Corbis 370 (b) Mark Thiessen/National Geographic Society. (bg) Boyd & Evans/Corbis. 371 (t) Steve Kaufman/Corbis. (m) George H. H. Huey/Corbis. (b) Gary W. Carter/Corbis. (bg) Macduff Everton/Corbis. 372 (b) Alissa Everett/Alamy Images. 373 (b) Taylor S. Kennedy/National Geographic Image Collection. 374 (bl) National Aeronautics and Space Administration. (mc) Citizens’ Voice, Dave Scherbenco/AP Images. (ml) Klaus Nigge/National Geographic Image Collection. (mr) Paul Chesley/National Geographic Image Collection. (tc) Jeff Greenberg/The Image Works, Inc.. (tr) Michael Nichols/National Geographic Image Collection. 376 (t) Roger Antrobus/Taxi/Getty Images. (tl) Mark Thiessen/National Geographic Image Collection. (tml) Ben Graville/eyevine/Zuma Press. (bml) Mark Thiessen/National Geographic Society. (bl) Mark Thiessen/National Geographic Image Collection. 376-377 (LesOp) Mark Thiessen/National Geographic Image Collection. 378 (bcl) Mark Thiessen/National Geographic Image Collection. (mbl) Mark Thiessen/National Geographic Image Collection. (mcl) Ben Graville/eyevine/Zuma Press. (tcl) Mark Thiessen/National Geographic Image Collection. (tl) Roger Antrobus/Taxi/Getty Images. (tr) Mark Thiessen/National Geographic Image Collection. 379 (mc) Mark Thiessen/National Geographic Image Collection. (tl) Roger Antrobus/Taxi/Getty Images. 380 (br) Mark Thiessen/National Geographic Image Collection. (tc, ml) Mark Thiessen/National Geographic Image Collection. (tl) Roger Antrobus/Taxi/Getty Images. 381 (bc) Jason Edwards/National Geographic Image Collection. (br) Andreas M. Gross/Westend 61/Alamy. (tc) Mark Thiessen/National Geographic Image Collection. (tl) Roger Antrobus/Taxi/Getty Images. 382 (bl) Pete Oxford/Minden Pictures/Getty Images. (tc) Mark Thiessen/National Geographic Image Collection. (tl) Roger Antrobus/Taxi/Getty Images. 384 (c) Mark Thiessen/National Geographic Image Collection. 386 (b) Roy Toft/National Geographic Image Collection. 393 (b) Photo by Eliot Elisofon/Time & Life Pictures/Getty Images. 395 (tl) Bettmann/Corbis Sygma/Corbis. (tr) Corbis. 395 (b) Michael A. Keller/Corbis. 396 (b) Annie Griffiths Belt/Corbis. 398 (b) SW Productions/Photodisc/Getty Images. 400 (bc) Corbis. (bl) Larry Williams/Corbis. (mc) Rob Walls/Alamy Images. (ml) Stockbyte/Getty Images. (mr) Blend/PunchStock. (tc) Todd Gipstein/National Geographic Image Collection. (tl) Jodi Cobb/National Geographic Image Collection. (tr) Bubbles Photolibrary/Alamy Images. 412 (b) Jamel Akib. (t) Nancy Yamin. 413 (r) Robert Harding Picture Library Ltd/Alamy Images. 414 (c) Images.com/Corbis. 418 (c) Hans Neleman/The Image Bank/Getty Images. 420 (b) KRT Photograph via Miami Herald/Newscom. 421 (r) Al Messerschmidt/Getty Images. 422 (b) Getty Images/Jose Luis Pelaez. 423 (t) AP Photo/HO, Randy Rodriguez, AIN. 424 (bc) Thomas J. Abercrombie/National Geographic Image Collection. (bl) Howard Davies/Corbis. (mc) Thinkstock/Corbis. (ml) Loungepark/Taxi/Getty Images. (mr) Myrleen Ferguson Cate/PhotoEdit. (tc) Stuart Westmorland/Science Faction/Getty Images. (tl) Inmagine/Alamy Images. (tr) Jodi Cobb/National Geographic Image Collection. 439 (t) Petras Malukas/AFP/Getty Images. 440 (b)