Maps and Geography (Ken Jennings’ Junior Genius Guides) - Hardcover

Über die Autorinnen und Autoren

Ken Jennings is the New York Times bestselling author of Brainiac, Maphead, Because I Said So!, Planet Funny, and 100 Places to See After You Die. In 2020, he won the “Greatest of All Time” title on the quiz show Jeopardy! and later succeeded Alex Trebek as the show’s host. He lives in Seattle with his family.

Mike Lowery is an author and bestselling illustrator who has worked on more than eighty books for children, including the Mac B., Kid Spy series with Mac Barnett, They Call Me No Sam! with Drew Daywalt, and more. He is also the creator of the Everything Awesome and Bug Scouts books. He lives in Decatur, Georgia, with his wife and kids, and his daily sketchbook can be seen at MikeLowery.com.

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Maps and Geography

The Earth from Space

“Geography” comes from the Greek word for “description of the Earth.” “Geo-” means “Earth,” like in “geology.” The “-graphy” part means “to write,” like in “graphic” or “biography.” So geographers study and describe the Earth.



This is the Earth. It is our home, unless any of you are aliens who have secretly invaded our planet for your own purposes. If so, please see me after class.

You might have heard or read that Columbus proved the Earth was round in 1492, when he sailed from Spain to the Caribbean. This is not even close to true! By Columbus’s time, scientists had known the Earth was round for almost two thousand years.

The Shape the World Is In

The earliest Greek thinkers disagreed about the shape of the Earth. Thales thought it was a round, flat disk floating in water, like a pancake that’s fallen overboard at sea.



Anaximander thought the Earth was a cylinder, while Anaximenes (no relation) believed it was a flat rectangle floating on compressed air.



But by 500 BC or so, most people agreed with the philosophers Pythagoras and Aristotle: The Earth was round, like a ball. There was good evidence for this.

If you really want to celebrate the discovery of round Earth, don’t celebrate Columbus Day on October 12—celebrate Eratosthenes (“air-uh-TOSS-thuh-neez”) Day on June 21! Eratosthenes was the Greek who invented the word “geography” and a very smart guy—in fact, he was the head librarian at the ancient world’s largest library, in Alexandria. Around 240 BC, Eratosthenes devised a very clever experiment to measure the Earth. In late June, on the longest day of the year, he had two sticks placed straight in the ground in two different cities, five hundred miles apart, and measured their shadows. The shadows were different lengths, which meant the sticks weren’t parallel—the Earth was round after all!



What’s more, Eratosthenes could use the length of the shadow to calculate the size of the entire Earth, without ever leaving Egypt. His measurement was about 24,600 miles, and today we know that the Earth actually measures 24,902 miles around at the equator. Eratosthenes was off by just a few hundred miles!

The Accidental Tourist

Columbus, however, didn’t get the memo. For his 1492 voyage, he relied on maps made by Egyptian scientist Ptolemy (the P is silent, luckily, or his name would be a pterrible ptongue ptwister). Ptolemy’s math led him to believe that Europe and Asia were quite a bit wider than they actually are, so Columbus thought he could circle the Earth in just 16,000 miles! The world’s best navigators at the time were the Portuguese, and they knew this was crazy talk. Their own guess was close to Eratosthenes’s: about 26,000 miles. Columbus set off anyway, sure that he could get all the way to China and India in a matter of weeks. Luckily, there was a big unknown continent in the way (Spoilers! It was North America!) or he would have been lost at sea forever. India was four times farther away than he thought, and he would have run out of supplies months before arriving.

Doing Their Level Best

Despite all the geographical evidence, there are people who still believe that the Earth is flat. The largest organization for these unscientific souls is the Flat Earth Society, founded by a British sign painter in 1956, the year before the space age began.



The Earth proposed by this group is a big, flat disk like Thales suggested, with the North Pole in the center. Antarctica is a big wall of ice around the edge, which luckily keeps the oceans from leaking off!

The society’s membership peaked at about two thousand in the 1970s, but today it’s down to a few hundred true believers. Of course, it’s a lot harder to believe in a flat Earth now that spaceships and satellites are orbiting the Earth and sending back pictures all the time. During the 1950s, the society’s founder was given one of the first photos of a round Earth taken from space. “It is easy to see how such a picture could fool the untrained eye,” he calmly replied.

Let’s Not Wait; It’s a Really Long Line

The grid of north–south and east–west lines that you see on maps is used to mark latitude and longitude. (IMPORTANT NOTE: These lines are imaginary! You will not see them by looking out the window of an airplane!) Latitude is a measurement of how far north or south you are, while longitude measures east and west.

Official Junior Genius Way to Remember Which Is Which

“Latitude” lines go from side to side, like the rungs of a “ladder.” “Longitude” lines travel from the North to South Poles—a really “long” way.



If you were to stand at one of the poles, it would take the Earth’s rotation a full day to turn you in a circle—in other words, you’d be moving veeeeery slowly. But at the equator, the surface of the Earth rotates a lot faster. Standing “still” at the equator, you’re actually moving at 1,070 miles per hour, faster than the speed of sound!

Math Homework

If you have an atlas (or GPS device) and a calculator with a cosine key, you can find out how fast you’re spinning right now! Find your latitude in degrees, enter it into your calculator, and hit the COS button. Then multiply this answer by 1,070 miles per hour. Presto! That speed is your current velocity! Wow, you’re getting a pretty good workout.

Pop Quiz!

What country’s name actually means “equator” in its native language?

Do You Come From a Land Down Under?

South of the equator is the Southern Hemisphere. Of course, no one in the Southern Hemisphere ever “falls off” the Earth—gravity keeps Australians and South Africans and Argentines firmly on the ground, just as it does for Americans and Europeans. But there are a few differences Down Under.

Because the Southern Hemisphere is tipped toward the sun while the Northern Hemisphere is tipped away from it, their seasons are reversed: In the Southern Hemisphere summer starts in December, and August is the depth of winter.



So an Australian Christmas doesn’t have sleigh rides and chestnuts roasting on an open fire—it’s more likely to involve a barbecue and a trip to the beach!

The moon is upside down in the Southern Hemisphere too: The Man in the Moon’s eyes are at the bottom, and a waning (shrinking) crescent looks like this.