by Kathi Wagner
Just for Fun
Going, Going, Gone
To see the effects of a black hole, ask your family if you can pour a few drops of food coloring into your bathtub drain while the water is running out. You can also create a whirlpool by taping two plastic pop bottles together at the tops. One filled with water and one that is empty. Then turn them over and watch what happens.
Misplaced in Space
Many years ago if you had asked an astronomer about space debris, he would have thought you were talking about stardust or chunks of planets and moons created when objects in space collided. Today, hazards in space are more likely to be manmade. With all you know about gravity, it is obvious that sooner or later, what goes up, must come down! Have you ever seen a really large meteor? Did you think that maybe it wasn’t a meteor at all? Maybe it was junk that was left behind when it could no longer be used, such as:
• A piece of equipment or an item that came off a spaceship or astronaut;
•A rocket booster after it ran out of fuel;
• Or even part of a spacecraft or a satellite.
Old space stations have returned to and burned up in Earth’s atmosphere after new, improved models have been lifted into space. Most of the tanks and other containers used for a shuttle liftoff never reach space. They fall into the ocean to be reused on another mission or burn up in the atmosphere. Parts of the rockets that were lifted above the atmosphere will probably drift in space for a long time. Are the remains of probes and spacecraft sent to other planets called interplanetary trash? You can use satellites, the shuttle, the Hubble telescope, and the space station to practice finding objects in space with your telescope. Since they circle the Earth at regular intervals and at certain places in the sky, you can be sure they aren’t meteors or junk!
In Search of a Planet!
Did you know that there over a million objects orbiting around the sun and they’re not that far away? If you were an ancient stargazer and you found Mars and then Jupiter, you might have wondered why there wasn’t another planet between them. When Ceres, an asteroid that is one-eighth the size of the Earth’s moon, was discovered, they thought it was. Today’s astronomers aren’t sure if that space ever held a planet or if there just wasn’t enough gravity to form one from the chunks of rock and metal circling in this asteroid belt. Some of these asteroids are as small as a compact car, while others are large enough for a spacecraft to land on them, and one even has a volcano! How would you like to have been in the probe that did land on one called Eros several years ago?
Try This
The Sky Is the Limit
Some of the satellites or other manmade objects can be seen with the naked eye while at other times binoculars work better. Try looking through a telescope to see them with more detail. Keep a journal of your finds and start a friendly competition with your friends to see who finds the most objects!
Just for Fun
Meteorite Collection
Lots of people collect rocks, but how about having a meteorite and rock collection? To start your collection all you will need is a box and a good location to find a few rocks. You will also need a book to help you identify which items are rocks and what may actually be items from space.
Too Close for Comfort
Not all of the asteroids are between Mars and Jupiter— some actually circle in Jupiter’s orbit and others cross Earth’s orbit. These are called near-Earth asteroids. Several times during the last hundreds of millions of years on Earth, huge craters were created when these objects reached the planet. Many scientists believe that the shock waves created dust storms, volcanoes, and possibly some 65 million years ago, may have killed off the dinosaurs! There are satellites that continually scan the skies to keep track of where the asteroids are since a planet’s gravity can pull them from their orbits. Each asteroid that they find is entered into a computer, so the scientists know where they should be and they continually monitor them to see if they are staying in the same orbit. You can help watch for asteroids outside the belt by using a star map and taking pictures of the sky. If a star seems to disappear, you might be seeing an asteroid crossing in front of it!
FUN FACT
Dust to Dust
Although most meteorites are as small as grains of dust, they add up to tons of material deposited on Earth each day!
Showers from the Sky
How would you like to have a fireworks show delivered to your door? Check the newspaper and watch to see when the next meteor shower is coming! Astronomers know where to tell you to look because the meteors are usually pieces of comets that are located in one area of the sky at certain times of the year. The meteors are pulled in toward Earth as it follows its orbit around the sun. Have you ever wondered why we call them meteor showers rather than meteorite showers? Because up in space, they are called meteoroids, then they become meteors when they reach Earth’s atmosphere, but they’re not actually called meteorites until they hit the ground. Have you ever seen someone try to rub two sticks together to make a fire? What they are doing is creating friction, light, and heat. This is the same thing that happens as the meteors rush through the Earth’s atmosphere.
Oops!
If meteorites are chunks of space rock that hit planets, what do you call chunks of space rock that miss the planets? You must figure out the special way to hold the book to read the silly answer to this riddle!
What Was That?
Some meteors cause a sonic boom like a jet because they are moving so quickly. They can also burst into flame, and if they are large enough they can be seen in the daytime and are called fireballs or bolides. The best time for you to see a meteor shower is usually after midnight, so gather the kit you have for watching stars and be sure to ask an adult to join you. Meteors can be seen even when a shower isn’t scheduled, so keep your eyes open. If you thought that you saw where a meteorite landed, would you know one if you found it? Some people like to try and find the pieces of a meteorite if they can tell where a big one has fallen. They organize hunts and will sometimes let volunteers help them look. The hunters can learn where the meteorite came from by having an expert check it out. Most of them are made out of metal or stone, just like the rocks here on Earth, but they were created when the solar system was forming. They can come from other planets, the moon, and asteroids. Keep watching the skies and maybe you will get to help look for one. If you think you see one, be sure to tell your family and have them help you watch it. To learn more about meteorites, type in “museum & meteorites” to see pictures of them and a list of natural history museums that display them.
WORDS to KNOW
METEORITE: The objects that fall from space onto the earth are called meteorites. When they start to burn in the sky, they are sometimes called falling stars.
COMET: A comet is an object that appears to have a glowing tail as it travels through space. One famous comet is Halley’s comet, known for its timely return trips
Just for Fun
Comet Balls
To make a comet ball all you need is a soft rubber ball or tennis ball, and some cloth ribbon or strips of cloth to use for its tail. Have an adult help you make a hole in the ball, and then push the ribbons into it or use duct tape to fasten the ribbons on it. Now toss your ball through the air.
What’s in a Name?
What’s another name for a large meteor? Are they just small asteroids that have entered Earth’s atmosphere? Some astronomers call Ceres a planetoid or a minor planet because of its size and the fact that it orbits the Earth. In astronomy’s constantly changing vocabulary, today it might be called a small dwarf planet! What do you think Earth Grazers (EGAS) would be? If you said it’s just another name for the near-Earth asteroids, you’re right. Just to make it more confusing, some people also called the meteors that skim the top of the atmosphere and leave a long, glowing line the same thing. Have you heard the word binary, which means two of something? Astronomers use it when they are talking about stars, but there are also bina
ry asteroids. When two people are born at the same time, we call them twins, even if they don’t look exactly the same. The same is true for binary asteroids. Some of these asteroids have satellites that make an orbit around them just like our moon does around Earth! So when is a moon not a moon? Would you believe that many of the moons in the solar system are actually captured asteroids? Many of them are very small, have weird shapes, and travel backwards as they circle their planets. Many of the moons located in Saturn’s rings are so small that they aren’t called moons anymore; they’ve been downgraded or reduced in name to moonlets!
A Tale of a Tail
Have you heard of Halley’s comet? It has made an appearance in Earth’s solar system at around 76 year intervals for more than 2000 years! Do you know that you can actually see the orbit of the comet as it moves slowly across the sky, goes behind the sun, and appears again? This huge, dirt-filled snowball can’t be seen when it starts the long journey at the edge of the solar system until the sun reflects off of it, just like the earth and the moon. Its long tail stretches across many millions of miles of the night sky as it is pushed away from the sun by the solar wind. Although the comet appears to be on fire, when its glowing tail passed over Earth in 1910 no one was injured. Some passing comets with longer orbits may not be seen again for hundreds of years and some never return. Would you like to have a space object named after you? Comets are usually named after the first person that discovered them. If you want to find your own comet, scan the skies and look for a fuzzy patch of light that seems to be in a slightly different area of the sky each night. Many stargazers have found comets with nothing more than a pair of binoculars! If you just want to look at one that someone else has discovered,ask your family to let you know when a comet is scheduled to appear again. They can help you keep track of them and the other interesting events by reading astronomy magazines or checking http://skychart.skytonight.com/observing/skychart/skychart.aspon the Internet. The first time you visit this site you may need an adult to help you type in your location and time zone. (If you would rather use another site, that would be fine too.)
Confusing Comets
This astronomer is searching for a special comet, but there seem to be a lot of choices! Which is the one he wants? Use the clues to find out!
The correct comet...
...must have 4 tails
...must have the tails on
the left side
...must be round
...must be smooth
FUN FACT
Touched by the Sun
Comets are called sun grazers because they come so near to the sun as they go behind it before they start back out into the solar system.
Out of This World
Imagine that you could take a ride on Halley’s comet. You know that it circles around the sun, but where would you be going on the return trip? You would have to travel billions of miles from the sun, past Neptune, to the source of most of the short-period comets. You might think your destination would be Saturn’s rings that are shaped like a plate and filled with thousands of icy snowballs known as Kuiper’s Belt Objects. Many astronomers wonder if icy Pluto and many of the moons orbiting the gas planets came from here. Have you ever wondered why the comets started their journey? A planet’s gravity may have tugged on them if they got too close or the comet could have been struck by debris passing through space. Your trip wouldn’t stop here if you were riding a long-period comet. They take hundreds, some of them millions, of years to orbit the sun so you could travel trillions of miles to the edge of the solar system! You’d be traveling to the Oort cloud, which encircles the solar system completely. Its comets can come from any part of the sky, not just from one direction like shorter-period comets do. You won’t see the Oort cloud on the Solar System Viewer on the Internet, because no one has really seen it, even with a telescope—astronomers just know it’s there! Be sure to check out the other orbiting objects in space. Even though the solar system is really big, some of these things look like they come pretty close to each other! Do you think as the universe expands or contracts that it will effect the orbits or courses of all these objects?
WORDS to KNOW
OORT CLOUD: There is thought to be a type of cloud that encircles our solar system, known as an Oort cloud. This cloud is believed to be the birthplace of some of the icy comets that can be found traveling through our solar system.
Chapter 8
Starry, Starry, Night
The first astronomers probably spent more time writing down what they saw than they did looking at the stars. Because they passed this information on to others, it was easier for the new stargazers to look for their own discoveries. Today’s astronomers continue to learn more about the creation and destruction of stars. Visiting a planetarium is like taking a guided tour of the universe that may make you want to learn more about the stars, the constellations, and all the interesting things that are happening in astronomy today.
Just for Fun
Indoor Night Sky
To make an indoor sky, take a large piece of black plastic and draw the night sky on it with a silver paint pen. Use a pencil tip to make a hole for each star in the plastic so your stars will shine from the light outside. Tape the sky over the open end of a large appliance box. You will need a door in the box to get inside.
Diamonds in the Sky
When it starts to get dark each night, which are the first stars you see? The brightest ones, of course! Over 2,000 years ago, Hipparchus developed a numbering system, one through six, based on the apparent magnitude or brightness of the stars he saw from Earth. A first or number one magnitude star was 100 times brighter than the faint stars in the sixth class. Over time astronomers have found some objects can be brighter than a one, so they started using a minus sign to indicate how much light there seemed to be. Do you think there are numbers higher than six? With modern telescopes, stars can be listed up to a thirty! Hip-parchus might have been surprised to see astronomers still use the information from his catalog today. Newer books have changed the amounts of a few of his numbers and many, many more stars have been added to his list. Suppose you and your friends are walking after dark and you see a light shining in the distance.
WORDS to KNOW
MAGNITUDE: The amount of light a star emits or gives off is called its magnitude. Astronomers measure the magnitude of the stars out in the universe by using a number system.
It could be a streetlight or a flashlight. How bright it is doesn’t tell you much about the light, if you don’t know how far away it is. Modern astronomers have learned how to measure the distance to a star and its apparent magnitude, or how bright it appears to us. They use both of these figures to determine the absolute magnitude or luminosity (true brightness) of a star. Scientists pretend that the sun and the other stars are all the same distance from the earth to figure their absolute magnitude. The sun has an apparent magnitude of –26.7 and absolute magnitude of 4.8. See what a difference a little distance makes!
Connecting the Dots
Have you ever seen what looks like animals or people hiding among the stars in the constellations? Ancient stargazers like the Chinese, Egyptians, Greeks, and people living in the Middle East saw some of these same creatures. Some believed they were gods and made up wonderful stories about them that are still retold today. Each of these groups of people had different names for the same clusters of stars or constellations. Sometimes some parts of one constellation were grouped with part of another, and many were never seen because none of the stargazers lived in the Southern Hemisphere. You might not be able see all of them, either. Eventually it was agreed that there were eighty-eight constellations in all, but many of the shapes had been changed. Do you really think Cygnus looks like a swan or Canis Minor and Major look like a pair of dogs? Although the stars that form the figures appear to be close in certain constellations, they may actually be billions of miles apart. And because they are moving, they might be in other constellations eventually. Like the
imaginary celestial equator above Earth that helps astronomers locate objects in space, there is also an imaginary circle called an ecliptic. This circle is where the eclipses of the sun and the moon occur. Some of the constellations seem to move along this circle. This circle swings from 23.5 degrees north of the equator to 23.5 degrees south of the equator as the earth orbits around the sun. Would you call the Big Dipper a constellation? To most astronomers it is an asterism, or just part of the constellation known as the Great Bear or Ursa Major!
WORDS to KNOW
CONSTELLATION: A constellation is a group of stars that together form an image in the sky. One constellation that is well known is Orion.
How the Constellations Got Their Names
Have you read a lot of fairy tales or watched them on TV? Most of these stories were written for children to enjoy, but they were also written to teach children good behavior and keep them safe. Their lessons were things like: don’t talk to strangers, be honest and kind or you might be punished. Ancient storytellers told stories about what they thought they saw in the sky, from mighty hunters like Orion to magical animals like unicorns and winged horses, or even things like a harp and a cross.
What’s Your Sign?
When people talk about constellations, do you think about the twelve symbols listed in the zodiac? Many people do because it’s fun to talk about astrology. The history of astrology goes back for thousands of years, and there is more than one type of astrology. In some cases the month when you were born is what counts while others rely more on the year you were born. Depending on what year you were born you may be under the sign of the rat or the monkey, or one of the other ten animals. Some people still believe that the date of your birth has an effect on your life. As the earth orbits the sun, several constellations are visible in the night sky for about a month right along the ecliptic circle. The sign in the middle is considered the dominant or main sign. In the monthly astrology, if you were born in the first part of the month of March, Pisces would be your sign. The sun, the moon, and the planets all appear to move through these special constellations during the course of the year. Maybe you have heard of some of the signs like the crab or the twins. If you think you might want to use astrology to predict your future, remember all of the changes that have been made in the calendars over the years. March 5 was probably January 21 thousands of years ago.
