An Earthling's Guide to Outer Space

by Bob McDonald

  YOU TRY IT! Cardboard Galileo

  With just a few household items, you can make your own refracting telescope, the same type used by Galileo more than four hundred years ago.

  WHAT YOU NEED

  Two magnifying glasses with handles

  A cardboard tube (the ends should be as large as the magnifying lenses)

  A sharp knife with a sawtooth edge

  Measuring tape or a ruler

  A pencil

  Tape

  A book

  WHAT TO DO

  Stand the book on its end on a table.

  Hold up both magnifying glasses, one in each hand, and look through both of them at the book. Move the magnifying glass closest to you forward or backward until the words on the cover come into focus.

  Measure the distance between the two lenses.

  Mark two points on the cardboard tube the same distance apart from each other as the two lenses. Draw a straight line on the side of the cardboard tube connecting them.

  Cut a notch into the cardboard tube at each endpoint. The notch should be wide enough to fit and hold the magnifying glass.

  Cut along the line connecting the two points so that you have a slot running along the length of the tube.

  Slide one of the magnifying glasses into the notch at one end so the handle is sticking out. Do the same with the other magnifying glass at the other end.

  Hold the tube up to your eye using the handles of the magnifying glasses and look at a distant object. Slide the lens closest to your eye along the lengthwise slot until the object you’re looking at comes into focus. You may have to cut more of the slot to find exactly the right spot.

  Congratulations! You have just made a telescope. Use it to look at distant buildings and birds, and at night try looking at the moon. You will be amazed!

  15 What’s So Special About the Hubble Space Telescope?

  The Hubble Space Telescope is probably the most famous telescope in the world, thanks to the perfectly clear, colorful images it has captured of objects all the way out to the edge of the universe. While it is not the largest telescope ever built, nor was it the first astronomical telescope sent into space, it was the largest to be sent into orbit, high above the turbulent, cloudy, and polluted air of the Earth’s atmosphere. That gives it the clearest view of the stars possible. And because of its high perspective, it can look into space anytime, unlike telescopes on the ground, which can only look up on clear nights. In space, the skies are dark and clear all the time!

  The telescope is named after Edwin Hubble, a famous astronomer who discovered that our galaxy, the Milky Way, is only one of billions of others like it scattered across the universe. Not only that, Hubble also found that all the other galaxies are moving away from us, a sign that the universe is expanding.

  Way back in the 1920s, Hubble began working at the Mount Wilson Observatory in California. He used the observatory’s one-hundred-inch reflector telescope, which was the largest telescope in the world at that time. When Hubble (the person) peered out at fuzzy spots in the sky that looked like clouds in space, he discovered that they were distant galaxies. But there was something strange about their light. They appeared to be redder than they should be.

  When an object out in space, such as a star or a galaxy, is moving toward us, the light waves are squeezed together a bit, making the light look blue. And when the object is moving away from us, the light waves are stretched out, so they appear red. The color of a galaxy, then, tells us whether it’s moving toward or away from us.

  The same thing happens when a train or car is passing by with its horn blasting. When the vehicle is approaching you, the sound waves are squeezed together, so the horn sounds higher. When it passes by, the horn becomes lower because the sound waves are stretched out. The faster the vehicle moves, the bigger the change in sound. When you are inside the vehicle, though, the sound of the horn does not change because you are moving with it.

  Hubble was astonished to discover that the light waves from nearly all the galaxies he observed were red. And it didn’t matter what part of the sky Hubble looked at: up, down… they were all “red shifted,” which meant they were moving away from us. It looked like we were at the center of the universe. Not only that, but he saw that the galaxies farthest away from us were moving the fastest.

  It all seemed incredibly strange. If all those galaxies were rushing away from us, that means they must have been closer together in the past. Logically, if we could run time backward and travel into the past, the galaxies would get closer and closer together. So it seemed the universe used to be smaller and everything was once packed into a tiny space. If we could go all the way back to the very beginning, the whole universe would have been squeezed into a single ball of hot energy… a powerful bomb waiting to explode.

  And explode it did. We came out of a big explosion, something scientists call the Big Bang. So not only does it appear that we were once at the center of the universe, but we were also in the middle of a big explosion.

  We think of explosions like fireworks, where everything bursts out of one spot and flies off in all directions, with the sparks traveling at the same speed away from the explosion site. But the Big Bang was the explosion of the universe itself. And since we live in the universe, we see the explosion from the inside out, which is why everything seems to be rushing away from us in all directions.

  Here is the really hard part to wrap your head around. The expanding universe is unlike fireworks in another way. The universe is not filling up a large, empty space the way fireworks fill the sky. The universe is expanding because space itself is getting larger.

  It’s tricky to think of empty space getting bigger, but that’s what Edwin Hubble saw when he looked at galaxies in space. Those farthest away were expanding faster than those that were closer, and that can only happen if space is stretching the way a balloon does when you blow it up: space expands and makes galaxies move away from each other, even though the galaxies themselves are not moving through space.

  Picture our universe as a deflated balloon. Imagine you’ve drawn dots all over it to represent planets and galaxies. Now imagine blowing it up. The planets and galaxies stretch away from one another as you blow, but they don’t change where they are on the balloon.

  Now picture a very tiny version of yourself standing on one of those dots. No matter where you were standing on that balloon, it would always look like you were standing still and all the other dots are moving away from you. It doesn’t matter what dot you stand on, the effect will be the same. What does this mean? It means that as far as we know, there is no center of the universe.

  So is there an end? Is there an edge to the universe? When you’re in a big crowd, surrounded on all sides by masses of people, you can’t see where the crowd ends, right? The same goes for our universe. We’re inside it, so we don’t see an edge. We don’t even know if there is an edge. It’s not like we can step outside the universe to take a look.

  The Hubble Space Telescope has proven that Hubble was correct—the universe is expanding. The telescope has even measured how fast it’s happening. It turns out, not only is our universe expanding, but the rate of expansion is speeding up! That means that it will never stop expanding. Eventually, many billions of years from now, all the galaxies will be so far away from us that we will no longer be able to see them. So get out and enjoy the night sky while everything is still within sight!

  YOU TRY IT! Make a Rubbery Universe

  When we think of objects getting farther away from us, they are usually moving through space. But the expanding universe is space itself between the galaxies that is getting bigger, which is hard to imagine. A rubber band helps to show how the effect that Hubble saw actually works.

  WHAT YOU NEED

  One thick rubber band

  A marker

  WHAT TO DO

  Make a series of dots along the rubber band that are all about the same distance apart. Hold the rubber band by the ends and
stretch it to see what happens to the dots. The dots are getting farther apart because the space between them is stretching. But the dots are not actually moving across the rubber. Rather, they are being carried along as it stretches. The same thing is happening in the universe. Space itself is expanding and galaxies are getting farther apart.

  Rest one hand on a table and hold one end of the rubber band still. Imagine being on the dot closest to your table hand while looking along at the other dots. Now stretch the rubber away from your hand on the table. Notice how the dot closest to the stationary end does not move as much as the ones farther away, and the closer you get to the moving end, the faster the dots are moving. Astronomers see the same thing happening in our universe. Galaxies that are the farthest away are moving the fastest. This can be seen in all directions in the sky, so it looks like we are in the center.

  Now rest your other hand on the table to hold the opposite end of the rubber band still. Imagine yourself on the dot closest to that hand while you stretch the rubber. Now all the other dots seems to be racing away in the opposite direction, but it still looks like you are at the center. In fact, it doesn’t matter what dot you choose; if you imagine standing on it as the elastic stretches, it will always seem like all the other dots are moving away from you and you are standing still.

  Finally, stretch both ends of the rubber band at the same time and make the center dot remain stationary. If you were on the middle dot, you would still see galaxies moving away from you and think you are in the center.

  In all of the methods outlined above, you were simply stretching a rubber band. No matter what dot you imagined yourself on, you would think you were in the middle of the rubber band universe. That’s one reason no one really knows where the middle of our universe is. We think we’re at the center, and no matter where you are in the universe, your perspective would make it appear as though that was exactly the case. The truth? If everywhere is the center, then there probably is no center!

  PART 3 Fly Me to the Moon… and Beyond

  Humans in Space

  16 How Do I Become an Astronaut?

  Astronauts are very special people. They have a good education, they’re strong like athletes, and they go through years of training before they fly in space. In the early days of space exploration, all astronauts were military test pilots. That’s because no one knew what it would be like to leave the Earth, and the rockets taking them there had never been flown before. Test pilots train to fly new types of aircraft and are used to putting themselves into dangerous situations. So they were considered the best people to become astronauts.

  But now, more than sixty years later, almost anyone can become an astronaut… if they possess the right qualities.

  STEP ONE: GET AN EDUCATION

  No high school dropouts have made it to space. An education in science, engineering, medical, or technical subjects will prepare you with the knowledge needed to fly in space. Astronauts have to know about the technology of rockets and space stations because if something breaks in space, it has to be fixed in space. You can’t call a plumber to repair a space toilet. Becoming a medical doctor makes you an excellent astronaut candidate because doctors are needed to treat anyone who gets injured or sick during a mission.

  Then there is the science you will be doing once you leave the Earth. There are all sorts of things being measured in experiments in space—the health effects of spaceflight on the human body, how plants grow without the effect of gravity, or the chemistry of combustion and how things burn in weightlessness. Some of those experiments, such as environmental studies of the Earth, look down at the planet from high above, while others use instruments to look out to the edge of the universe. People from many different science backgrounds are needed to accomplish it all.

  Finally, now that astronauts from many different countries fly to space together, you will likely have to learn another language.

  STEP TWO: BE PHYSICALLY FIT

  No one who is overweight or out of shape has crawled into a spaceship and blasted off the Earth. Spaceflight is hard on the body, so you have to be strong to survive it. During launch, you feel three times your weight from the acceleration of the rocket. Then, as soon as the engines shut down, you are thrown into instant weightlessness, which gives you a sense of falling that can turn your stomach. If you remain in space for many months, your body becomes weaker because your muscles don’t have to work as hard when you don’t weigh anything. And after all that, you have to handle the gravity of Earth after you return. All of this takes strength and stamina. You don’t have to be an Olympic athlete, but you do have to be very fit and exercise often.

  STEP THREE: BE A TEAM PLAYER

  No one flies in space alone. It takes a team of people to fly in space and another even larger team on the ground to keep them safely up there. If you are the type of person who prefers to do everything yourself or who doesn’t like to work with others, you won’t be chosen to become an astronaut. Space is a very dangerous place, so astronauts need to look out for one another. If a task becomes too difficult or something goes wrong, you have to be able to ask for assistance and know that your crewmates will be there to help.

  * * *

  If you’re one of the lucky few who is chosen to become an astronaut, you’ll eventually end up training at the Johnson Space Center in Houston, Texas, and the Yuri A. Gagarin Research & Test Cosmonaut Training Center in Moscow, Russia. All astronauts go to these centers to learn how to fly spacecraft, do space walks, and operate the equipment on the International Space Station. The experience at those centers is as close to actually flying in space as you can possibly get.

  It takes at least two years of basic training to become an astronaut. A lot of that involves time in classrooms, where you learn about the science of spaceflight, orbits, how to rendezvous with other spacecraft such as the International Space Station, and the details of reentry into the Earth’s atmosphere. Then it takes several more years of training while you wait to be assigned to a mission. During that time you will learn how to do space walks in a giant swimming pool and help with missions already in space by becoming the “CAPCOM,” or capsule communicator, who speaks directly with the astronauts in orbit.

  In one building in Houston, there’s a full-size replica of the International Space Station, where you can step inside the different modules, see how the equipment is laid out, and practice all the activities you’ll be doing in space. You’ll be taken up in jet aircraft to experience the forces that are felt during rocket launches, and you’ll work with teams of other astronauts, cosmonauts, and ground engineers to make it all happen.

  When a rocket blasts off, your body is squeezed by the sudden acceleration, the same way you are pushed into the seat of a car when it accelerates quickly at a green light. But rockets take off much faster than cars, going from zero to the speed of sound in about a minute and up to thirty thousand kilometers per hour in only eight minutes, so the force you feel on liftoff is a lot more than what you’d experience in a car.

  SPACE PLACES

  Here are some centers where you can get a taste of what it is like to become an astronaut.

  SPACE CAMP

  Located in Huntsville, Alabama, and home of the first American rocket scientists, this camp has full-size simulators of the space shuttle and space station. After you climb in, you can feel what it’s like into launch into space, walk on the moon, and work in zero gravity—or even operate a console in mission control during a mission.

  CAMP KENNEDY SPACE CENTER

  This camp is located at the Kennedy Space Center in Florida, where real rockets launch into space. Besides all the activities of other space camps, you will have a chance to meet an astronaut, tour the genuine NASA launch facilities, and, if you time your visit right, maybe see a rocket launch for real.

  COSMODOME

  This space center in Laval, Quebec, holds artifacts from the Canadian space program as well as spaceflight simulators and a space camp.


  LYNDON B. JOHNSON SPACE CENTER

  Real astronauts go to Houston to learn how to fly in space. It is also mission control for the International Space Station. You can take a tour of the buildings where astronauts train, see a real moon rocket, and fly simulators at the visitor center.

  One device used to train for the stresses of launch is a centrifuge, a long swing arm with a capsule on the end. The seat inside the capsule has a four-point harness, like those in a fighter jet, that goes over your shoulders and across your thighs to keep you in tight. When the door is closed, you can’t see out, so when the arm begins to smoothly swing around, you don’t really feel like you are moving. What you do feel is your body pressing down into the seat as though you are gaining weight. As the speed increases, so too does the force on your body until you feel three times heavier than you would in a normal chair. That is the force astronauts feel during a launch into space. When a Russian Soyuz capsule returns to Earth and hits the atmosphere, the force, known as g-force, can go up to six or seven. Even at just three gs, the body feels heavy and you have to work harder to lift your arms over your head in order to flip switches. That is one reason astronauts exercise a lot. They need to be strong just to get off the Earth.

  Everyone who flies in space must get used to the fact that their body, and everything else around them, has no weight. You can fly through the air like Superman or Supergirl with a simple push off a wall. And you can fly in any direction because up and down no longer exist, and anything you hold out in front of you will stay there when you let it go. Nothing falls to the floor. If you need to pass something to someone else, simply float it across the room.