Outer Space (Ken Jennings’ Junior Genius Guides) - Softcover

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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Outer Space

Our Mr. Sun
Have you ever complained about the Sun, Junior Geniuses?

“It’s too hot today!”

“Ugh, that’s bright.”

“No more sunscreen, Mom!”



Well, after today’s lesson, I never want to hear you bad-mouth the Sun again! The only reason that life can exist on Earth at all, everything from figs to walruses to TV repairmen, is because of the light and warmth we get from our nearest star.

This is the Sun.



Wait, that’s not right. Why would the Sun need to wear sunglasses? Think about it; how would that help? Let’s try that again.



No Crayons Allowed

Please don’t color this drawing with a yellow crayon, Junior Geniuses. Not only would that deface this fine book, it would also be scientifically inaccurate! Sunlight only looks yellow to us because we’re seeing it through our atmosphere. From space the Sun is perfectly white!



When you look at the Sun—wait, hold on. Public service announcement:



The light is so intense it can literally cook the retinas in your eyes. To observe the Sun, glance and then look away. Don’t stare. There are health faddists called “sungazers” who claim they get all their nutrition from staring at the Sun a few minutes a day. But that really doesn’t work, so please don’t try this.



Okay. When you briefly glance at the Sun, you’re actually looking back in time! Sunlight travels at the speed of light, which means it takes an average of eight minutes and twenty seconds for it to reach the Earth. So the Sun outside your window isn’t actually where you think it is. By the time you see it, the real Sun has moved forward two Sun-diameters in the sky.



But we’re going to travel back in time even further: not eight and a half minutes but 4.5 billion years! That’s when the story of our solar system begins.

A Star Is Born

Over 4 billion years ago a nebula—a gigantic space-cloud of gas—collapsed on itself, possibly due to the shock wave from a nearby exploding star. As it shrank, the whirling cloud began to spin faster and faster and grow hotter and hotter. It flattened into a big pizza-shaped thing called a protoplanetary disk, and soon thereafter (just 50 million years—that’s “soon” in cosmic terms!) the middle of the disk got hot enough to light its nuclear furnace. The Sun was born!



A lot of the leftover dust and gas spinning around the new baby Sun began to clump together, which is how planets form. But these weren’t the planets we know today! There were probably hundreds of little planets zooming around and smashing into each other, until they merged into bigger ones. Others collided at such high speeds (due to the immense gravity of big planets like Jupiter and Saturn) that they shattered into tiny chunks called asteroids.

Today, just eight main planets survive, most of which we’ve named for different gods of Roman mythology.



Pop Quiz!

Since classical times, we’ve used special symbols to refer to the planets and most refer to mythology. The Venus symbol, , looks like a mirror, because she was the goddess of beauty. Mars looks like a spear and shield, , because he was the god of war. What is the Neptune symbol, , supposed to be?

Spaceballs

But that diagram isn’t quite accurate, because the solar system is much, much bigger than we can draw in a book. The Sun is massively bigger than everything else, for one thing. It accounts for 99.8 percent of the mass of the solar system! (Jupiter is most of the rest.)



The distances between planets are even harder to imagine. Let’s pretend that a superpowerful alien has somehow shrunk the eight planets of our solar system to fit inside a baseball stadium. (This alien is apparently a big baseball fan.) The solar system is so big that our massive Sun would be the size of a golf ball, sitting at home plate! At this scale, Mercury is a dust speck in the batter’s box, while Venus and Earth are grains of sand near the edge of the home plate circle. Mars is another dust speck one-third of the way to the pitcher’s mound. Jupiter and Saturn are the sizes of apple seeds, with Jupiter sitting just past the pitcher’s mound and Saturn at second base. Uranus is a pinhead near one of the foul poles, and Neptune is a pinhead at the fence in deep center field. (Pluto got kicked out of the ballpark in 2006 for arguing with the umpires. Hit the showers, Pluto.)



Here’s the bottom line, Junior Geniuses: Space is incredibly big. Our little solar system by itself—our own tiny neighborhood in a vast galaxy—is so big that it fries even my amazing brain when I try to think about it.

Junior Genius Joviality!

Ask a grown-up how far it’s possible to see on a clear day. I guarantee they will guess low! The correct answer, as long as you can see the Sun, is “93 million miles.” That’s also known as one “astronomical unit”—the distance from the Earth to the Sun.

Whirled News

Today we take it for granted that the planets of the solar system spin around the Sun, but for most of history people have assumed that the Earth was the center of the universe! Five hundred years ago heliocentrism (“hee-lee-oh-SENT-rizz-um”), or the idea that the Sun was the center of things, was so controversial that people who believed it could be put on trial. The great astronomer Galileo spent the last ten years of his life under house arrest for insisting it was the Earth that moved around the Sun, not the other way around.



But—sorry, Galileo!—that doesn’t mean the Sun is the exact center of the solar system! Gravity works both ways, Junior Geniuses. The Sun tugs on each planet—take Jupiter for instance—in a big way, because the sun is so massive. But, at the same time, Jupiter is tugging on the Sun in a small way. Instead of saying that Jupiter orbits the Sun, it’s more accurate to say that they both orbit a third point, called a barycenter, which is about thirty thousand miles above the surface of the Sun.



Are You Sitting Still?



The Earth is moving at a pretty good clip right now: spinning on its axis at 1,000 miles per hour and whirling around the Sun at 66,000 miles per hour. But don’t forget that the Sun is moving too, spinning around the Milky Way like a giant pinwheel at about 483,000 miles per hour. And today scientists can use leftover radiation from the Big Bang to measure how fast our whole galaxy is moving through the universe: 1.3 million miles per hour!

We don’t feel any of this motion, of course, because everything around us is moving at the exact same speed we are. But the next time a grown-up says, “Have you been sitting in that chair all day? Get up and get some exercise!” tell them you’ve already covered a few million miles today, and you’re pooped!

All Systems Glow

But let’s take a close-up look at the Sun. (NOTE: AGAIN, DO NOT TAKE A REAL CLOSE-UP LOOK AT THE SUN. IT IS VERY BRIGHT.) Luckily, Mr. Sun produces a lot of energy, or we would be very cold right now and bumping into things all the time. But where does that energy come from?



At the middle of the Sun is a very dense core, where the pressure gets pretty intense—over one hundred times what it is at the bottom of Earth’s oceans, in fact. All that gravity pushes atoms together with a pressure of one hundred tons per square inch, enough to crush atoms into...