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The Universe Alston Potts Ben Caulfield Jesse Bond 2 Table of Contents Big Bang p. 3 p. 4 p. 5 p. 6 p. 7 p. 8 The Beginning Events of the Big Bang Matter Energy Universal Expansion History of Human Understand of the Big Bang Galaxies p. 9 Introduction p. 10 Formation of Galaxies Galactic Phenomenon: Black Holes p. 11 Galactic Interaction p. 12-13 p. 14 Supernovas Types of Galaxies: Elliptical p. 15 Spiral p. 16 p. 17 Lenticular Dwarf p. 18 Irregular p. 19 Star Systems p.20 p.21 p.22 p.23 p.24 p.25 p.26 p.27 p. 28 p.29-30 Introduction: What is a star? Formation of Stars Types of Stars Neutron Types of Star-related Systems: Planetary Systems Binary and Multiple Star Systems Glossary About the Authors Image Credits 2 3 The Beginning The most widely accepted scientific theory on the beginning of the universe is known as the Big Bang Theory. Scientists believe that all matter, life, and energy began as a singularity. This zone is believed to exist at the center of a black hole as exAn artistic interpretation of the Big tremely tiny, infinitely dense, and Bang molten hot particle (one for every black hole). Many people believe that the big bang was the result of an exploding singularity, but many scientists believe that it occurred because this particle (singularity) rapidly inflated to the size of our current universe, cooling down as it expanded. The universe continues to expand and cool down, and, as far as scientists can predict, will continue to do so forever. Did you know? Scientists from New Jersey, Arno Penzias and Robert Wilson, accidentally discovered the existence of cosmic microwave radiation while trying to intercept radio waves. Because of this discovery they were awarded the Nobel Prize in Physics and brought us one step closer to discovering the beginning of the universe. 3 4 Events of the Big Bang The Big Bang Universe begins to expand Gravity becomes evident Formation of the basic elements Radiation forms from the initial energy of the Big Bang Energy in matter and radiation become equal Stars and galaxies form Satellite image of our sun. Did you know? Our sun formed approximately five billion years ago, which is very young in the life of the universe. It is believed to be about fourteen billion years old. 4 5 Matter Everything in the universe can be divided into one of two categories: matter and energy. Matter can be identified by its characteristic elements known as atoms. An atom has protons, neutrons, and electrons A representation of the three states of matter. within its structure. These are known as subatomic particles. All matter can exist in three stages: solids, liquids, and gases. Both solids and liquids have a fixed volume, while gases take on the volume of the containing space. Temperature is the factor that ultimately decides what form matter will take; matter is in solid form at cold temperatures, in liquid form at warmer temperatures, and in gas form at the warmest temperatures. The temperatures in which these forms occur are different with every different kind of matter. Did you know? Many cosmologists theorize the existence of a strange form of matter known as dark matter. This explains the space between celestial bodies. The scientists say that this kind of matter does not actually have any atoms, so it is incorrectly labeled. 5 6 Energy Energy, on the other hand, is not made up of atomic nuclei. Most energy can be found on the light spectrum, which ranges from radio to gamma rays. Energy can be organ- The light spectrum, the projected area is all that we are ized into categories able to see based on the size of the wavelength, varying from energies of long wavelengths to energies of shorter wavelengths (lower energy to higher energy). Humans can only see a small portion of all waves found in the universe; these waves are found in the visible portion of the spectrum. Cosmic rays do not have a place on the spectrum because they are particles with high charges that travel through space at the speed of light. Did you know? With the aid of current technology such as infrared cameras and ultraviolet light bulbs we are able to see some of the waves on the spectrum that we are naturally unable to sense. 6 7 Universal expansion The universe is constantly expanding. This actually occurs in the space between celestial bodies such as stars, planets, and asteroids. If you imagine a loaf of raisin bread you may understand this conThis image shows the path of expanding galaxies/ cept better. Before you bake the bread, it is a dense wet dough with raisins mixed into it. When you put the dough in the oven and begin to bake it, the bread expands. But do you think the raisins expand along with the dough? Of course not. The sizes of the raisins are not affected by expanding bread; however, the distance between them increases. The masses, or raisins, do not change in size, but the space, the dough between them, increases. Unlike the bread, would eventually reaches a point where it stops expanding and burns, the universe never stops 7 8 Human Understanding Of The Big Bang Edwin Hubble (1889-1953) was an American astronomer who discovered that there are more galaxies than just our galaxy. From this discovery he developed Hubble’s Law, which simply states that the universe is continually expanding. This law lends proof to one of the most widely known scientific theories, the Big Bang Theory. Despite its familiarity, there remain a few misunderstandings about the theory. The most common misconception is the belief that the Big Bang actually started with a big noise. There was, however, no explosion because this event is believed to be more like the inflation of a balloon rather than a bang. Another incorrect idea is the belief that before the Big Bang there was just one singularity floating in space. There was, however, no space during this time - just the one speck and nothing else. 8 9 GalaxIES Hoag’s object (top) , the sombrero galaxy (middle) , and two colliding spiral galaxies (bottom). Galaxies are gigantic collections of stars, gas, dust, and remnants of dead stars. They are formed when a large black hole appears and uses a gigantic amount of gravity to pull galactic debris towards the center. Galaxies are grouped into different types, including spiral, elliptical, lenticular, dwarf and irregular galaxies. They range in shape, size, amount of stars, and visible appearance. Although some exist solely by themselves, many galaxies are organized into galactic clusters, which are also held together by gravity. These clusters can then be organized into super-clusters, which are the largest objects in the universe to be held together by gravity. 9 10 Galaxy Formation Following the trend of starting small and getting bigger, galaxies also began the same way. Galaxy formation is still being actively researched, but it is believed that the phenomenon began approximately 300,000 A newly formed galaxy is shown in the bottom left portion of this image years after the Big Bang. It began with recombination, which is the formation of neutral hydrogen and helium atoms by the combination of stray protons and electrons. As the galaxy continues to develop, it starts to form galaxy clusters with other galaxies. This period in the existence of a galaxy is known as its evolution. At this time the key structures begin to appear, such as the central supermassive black hole and stars. 10 11 Black Holes You’ve probably heard something about black holes in science fiction, in the news, or in school. A black hole is usually described as a mysterious black object that will suck anything into it. These lurking monsters are often said to lurk in the deepest reaches of the universe. In reality, this description of a black hole is only partly This artist’s rendering of a black hole shows that true. In the universe, black light even light can’t escape this massive amount of holes area naturally occurring gravity. phenomena. First, we must discover how black holes are formed. On the page prior to this, you learned about supernovas and the death of stars. In some rare occasions, an exploded star will collapse in onto itself from an overwhelming amount of gravity. Note that this is the same gravity that makes apples fall from trees on earth, but a much stronger amount. The collapsed star will become what is known as a black hole. Now you may be wondering, ―What makes this collapsed star a black hole?‖ A black hole has such an exceptionally gigantic amount of gravity that it is able to consume anything that wanders too close to its surface. It even will cause light to become trapped inside of its menacing body. Without light to bounce back, the entity is perceived as a black object. Did you know? To our knowledge, light travels faster than anything else in the entire universe. It clocks a whopping speed of 671,000,000 miles per hour! To put this into perspective, the fastest man made jet travels at only 2,293 mph. 11 12 Galactic Interaction The mice galaxies are two interacting galaxies that are in the process of colliding with each other, Galactic interaction occurs when one galaxy is distorted by another. It appears by a variety of processes, including satellite interaction, galactic collision, and galactic cannibalism. Satellite interaction, which is found in smaller galaxies orbiting larger counterparts, can affect both the satellite and the mass it orbits. The larger object, or primary, is capable of completely disfiguring the smaller galaxy. The satellite, on the other hand, can gravitationally pull the arms of the primary outward. Galactic collision can occur between two galaxies of any size or type and can have a far greater impact than satellite interaction. You might imagine these collisions as colossal crashes of galactic proportions; however, because matter is distributed loosely in galaxies, these collisions are not the expected impacts. In reality¸ colliding galaxies only affect each other through gravity, and they may even pass through each other unaltered. On the other hand, if the galaxies lose their momentum, they might merge into a single, larger galaxy. 12 13 Galactic Interaction This image shows galactic cannibalism as a larger galaxy collides with a smaller one. The final type of galactic interaction, called galactic cannibalism, occurs between two galaxies of greatly different sizes. The larger galaxy pulls the other mass towards it, and the matter from both objects is combined. In this process, the larger galaxy remains generally unaffected, but the smaller galaxy is almost completely destroyed. 13 14 Supernovae A supernova is an enormous explosion that is formed when a star (see p. 21) becomes too massive and too old to support itself and collapses. Although supernovae can come in many forms, they are normally classified into two main types. The first type is formed when a small This picture of the Keplar supernova star gives some of its shows the brightness and energy that is common to most supernovae. matter to another, equally tiny star. The tiny star eventually gains too much mass to maintain itself and explodes into a supernova. The second type of supernova is formed when an already massive star becomes too old and runs out of energy. With no other forces involved, gravity is left to pull inwards on the star, which collapses into a supernova. The explosion itself is a spectacular burst of light so bright that it can occasionally outshine an entire galaxy. Did you know:? Supernovae give off 1038 tons of energy. That’s more than an 14 octillion nuclear bombs! 15 Spiral Galaxies Of the various types of galaxies, the spiral galaxy is by far the most common. In fact, About 77% of all known galaxies are spiral. There are a few main features that are found in all spiral galaxies, including a disc-like shape and a galactic bulge. The discs are usually This image of a spiral galaxy clearly formed by two spiraling arms shows the two spinning arms, the orbiting halo of stars, and the bulge that come from the center of of stars in the center. each galaxy. The galactic bulge, which makes up the center, is a dense group of older stars. In addition, all spiral galaxies have a center made of a large black hole: a large opening in space with such strong gravity that even light cannot escape it. Finally, all spiral galaxies have a so -called halo of loosely packed stars that are found far-off from the center of the galaxy. Although all spiral galaxies show these characteristics, they greatly vary in overall size, density, and brightness. Did you know? The Milky Way, which is the galaxy that we live in, is a spiral galaxy. 15 16 Elliptical Galaxies Bright, white galaxies are classified as elliptical. Because of their brightness, we usually can’t see any features in these galaxies. Some elliptical galaxies have only a hundred million stars, while others contain as many as one trillion stars, most of This picture of the M87 galaxy clearly which are older and shows the bright, sphere-like shape that is smaller than normal. In common to elliptical galaxies. addition, because there isn’t much dust or gas in elliptical galaxies, they form stars very slowly. Unlike most other galaxies, elliptical galaxies are almost always found in galaxy clusters. Astronomers believe that elliptical galaxies form when two other galaxies pull towards each other and collide. Although these impacts were very common at the beginning of the universe, they are somewhat uncommon now. In fact, only 15% of all galaxies in the visible universe are elliptical. Did you know? Some elliptical galaxies are 100 million light-years wide! 16 17 Lenticular Galaxies There are some galaxies that are neither elliptical nor spiral; they are a mix of both groups. These masses, called lenticular galaxies, make up one of the most common types of galaxies. They have shapes, sizes, and stars that are similar to spiral or elliptical galaxies. Much like the spiral galaxy, lenticular masses have spiral arms; however, lenticular curves are not quite as distinct. In addition, lenticular galaxies have a disk-like This lenticular galaxy has both the brightness of an elliptical galaxy and shape, which is also simithe disk-like shape of a spiral galaxy. lar to that of spiral galaxies. Much like elliptical galaxies, on the other hand, lenticular galaxies have a very bright galactic bulge. In fact, this bulge is so similar to that of an elliptical galaxy that, when viewed from the front, the two galaxies are almost indistinguishable from each other. Furthermore, both elliptical and lenticular galaxies have low rates of star formation and contain mostly old stars. Lenticular galaxies combine both spiral and elliptical aspects to form a unique type of galaxy. 17 18 Dwarf Galaxies Dwarf galaxies are particularly small galaxies that contain very few stars. Galaxies of any type, such as spiral or elliptical, can also be considered dwarves. Although most dwarf galaxies This is an image of a dwarf spiral galaxy. have relatively small amounts of stars (a few billion), some dwarves, which are called ultra-compact dwarves (UCD), have as many stars as actual galaxies. One of the most interesting characteristics of dwarf galaxies is the way they move. Unlike most galaxies, dwarves are neither grouped in clusters nor alone in space; instead, these masses are in orbit. In the same way that planets revolve around the sun, dwarf galaxies move about larger galaxies. Such orbiting galaxies are also called satellite galaxies. Did You Know? There are at least 14 dwarf galaxies orbiting the Milky Way. 18 19 Irregular Galaxies Not all galaxies have tidy, circular shapes. Galaxies with distorted structures are called irregular galaxies and are both unique and chaotic. Irregular galaxies usually contain large amounts of gas and dust which leads to a high rate of star These irregular galaxies, known as the formation. Astronoantennae galaxies, are in the process of mers believe that merging together. these irregular masses form when normal galaxies are distorted through galactic interaction (see pp. 13-14). Irregular galaxies are categorized into two main groups, the first of which is called the IRR-1 group. Galaxies within this category display a structure that is too indistinct to be considered a normal galaxy. IRR-2, which is the second type of these irregular, heavenly masses, contains galaxies that have no organization at all. Each type is fairly common, and the combination of both groups makes up about 25 % of all galaxies in the visible universe. 19 20 What is a Star? As you probably know, the sun is a star. If you look up to the night sky you will be able to see rays of light emanating from countless other stars located in the galaxy. That’s all well and good, but what is a star? A star is a massive cloud of gas held together by gravity. It causes the star to implode in upon itself by applying enor- A picture of our Sun mous amounts of force on the gas. However, as the gas is squeezed together, the outward pressure of the hot gasses counteracts the effect of gravity. The result is a relatively stable ball of highly energetic gasses. In the center of a star, high-energy chemical reactions occur that expel energy from the stellar body. One of the most recognizable forms of energy expelled in this manner is light, which give stars the appearance of being ball of light. Did You Know? The ancient people Greece and Rome would often look up at the night sky and connect bright stars with lines; the ancients could picture exotic animals, legendary heroes, and mythical creatures from the shapes that were formed, which are now called constellations. 20 21 Formation of Stars v Galactic dust and gas clouds are the locations for the birth of stars. The natural pull of gravity between all matter causes clumps of dust and gas to form over vast quantities of time. Eventually, the clumps will coalesce into even larger clumps. Gravity will then cause the dust and gas cloud to collapse into a and Gas Cloud—Birthplace of much denser body. During Dust Stars this process, the center of the cloud will become increasingly hot. This is what is known as a protostar, or the beginnings of the core of what will become an actual star. If there is rotation in the cloud, there is a chance that the final collapse will cause the gas cloud to form multiple blobs of matter. In some cases, each of these blobs might form individual protostars. Did you know? The process described above is how scientists believe every star in the universe was formed. This process is even observable in the current day via powerful telescopes. Dust and gas clouds have been observed in each of the stages of stellar formation. 21 22 Types of Stars The numerous categories of stars range in both size and color. The majority of the stars are main sequence stars. Our sun is categorized as a main sequence star. The brighter the star, the hotter it is. The Diagram comparing color, size, and brightness life expectancy is over 5 billion years. Towards the end of a star’s life, it will begin to expand becoming what is known as a giant or supergiant. The final stages of its life are exploding in a supernova followed by becoming a black hole, white dwarf, or neutron star. Did you know? A white dwarf is roughly the size of the Earth. It is a small, hot, and bright. The final stage is a black dwarf, which is small, cold, and dark. 22 23 NeutroN Stars A neutron star is formed after the remnants of a supernova collapses from the pull of gravity. Much like white dwarfs, neutron stars are very hot and small. The length from end to end would be around 15 miles long. This is approximately 60,000 times smaller than the sun! Their density is over 200,000,000,000,000 times more than the density of the sun. The gravity on the surface of an average neutron star is stronger than on Earth by a factor of 100,000,000,000. The star will have a solid outer crust that is less than 1 mile thick. Inside the crust is a liquid interior of molten matter. A representation of a neutron star. 23 24 Star Systems Stars form a multitude of different systems in the universe. A few of the more prominent types that will be discussed on the following pages will be: planetary systems, binary star systems, and multiple star systems. Below are various pictures and artist renditions of each type. Top: Planetary Systems, Middle: Binary Star Systems, Bottom: Multiple Star Systems 24 25 Planetary Systems A planetary system is a star that has orbiting objects within its gravitational pull. As the dust and gas coalesce into clumps of matter some of the outer clumps do not become part of the star. A planet is a remnant left over from the formation of the star that it orbits. During birth of the planetary system, the largest collections of matter will continue to combine and grow. A planet has enough gravity to form a rounded, sphere-like surface. In our solar system, there are 8 planets that orbit around our sun (Pluto isn’t considered a planet anymore). A smaller type of object that is present in planetary systems is known by either the name asteroid or planetoid. They are often depicted as jagged lumps of rock and ice that do not have any particular shape. Scientists believe that planetoids are the building blocks of planets. In some planetary systems, rings of asteroids will form asteroid belts that orbit the star in the center of the system. Formation of a Planetary System 25 26 Binary and Multiple Star Systems A basic star system usually contains one star at the center of the system. However, a binary star system has two stars present in the system. The larger of the two stars is deemed the primary star, while the smaller is called the secondary. Both stars’ Binary star system with a red giant and a blue gravity will pull on the giant. other. This results in the two stars orbiting around each other. A multiple star system is similar to a binary system, but contains more than two stars. The additional stars will add their gravitational influence to the system. The resulting orbit of each star will be more complex than those of a binary system. The Search for Extra Terrestrial Intelligence (SETI) Institute is a nonprofit organization that researches and educates astrobiology, the study of life in the universe. The name, SETI, is an acronym for the Search for Extra-Terrestrial Intelligence. Currently, SETI scans the night sky with special telescopes for signs of life in deep space. The telescopes look for the presence of rhythmic or repetitive signals, as they do not occur naturally in the universe. If you find SETI interesting, they are always willing to have more help in their ongoing quest. Luckily, SETI@home is a freely available computer program that allows personal computers to analyze SETI’s overwhelming amount of unprocessed data. Since June 2009, over 300,000 computers have been involved in the project! 26 27 Glossary Atom-the smallest part of an element having the chemical properties of the element Big Bang Theory- the idea that the universe used to be small, dense, and hot. Coalesce - to combine or become one Energy-the ability to do work Galactic cannibalism– when a primary galaxy swallows its satellite galaxy. Galactic collision– when two galaxies use gravity to affect each other. Hubble’s Law-the statement that galaxies move away from each other Implode - Opposite of explode; to collapse into oneself Light spectrum-the range of all possible frequencies of radiation Matter-a substance that has mass and occupies space Orbit/Orbiting - Moving in a curved path around an object Primary– the larger galaxy that a satellite galaxy orbits. Recombination- the formation of neutral hydrogen and helium Satellite interaction– The interaction between a smaller, orbiting galaxy and a larger one. Satellite galaxy– a smaller, orbiting galaxy. Singularity-the center of a black hole Subatomic particle-particles that make up atoms (protons, neutrons, electrons) by the combination of stray protons and electrons. 27 28 About the authors Alston Potts, who wrote the Big Bang, matter, and energy portion of this book, is a Junior at the Massachusetts Academy of Math and Science at WPI. Before coming to the Academy he attended Fitchburg High School. He enjoys playing baseball and guitar. In the future, he wishes to learn to box. He is looking to attend West Point and become a civil engineer. Ben Caulfield, who wrote the galaxy section of this book, is a Junior at the Massachusetts Academy of Math and Science. In his spare time, he enjoys listening to music, playing his guitar, and reading. His favorite artists include Phish, Frank Zappa, Bob Dylan, and Blink-182 In the future, he plans to attend the Worcester Polytechnic Institute. Jesse Bond, who wrote the section about stars, is attending the Massachusetts Academy of Math and Science as a currently a junior. He is interested in robotics and has competed in numerous leagues and events. One of his most prominent involvements is with Team 190, a FIRST robotics team where he is the acting president and school representative. His father has introduced Jesse to amateur astronomy over the years and has ready access to a telescope that he may use whenever he chooses. Jesse Bond has also attended Stellafane, an annual international astronomy located in Springfield, Vermont. 28 29 Image credits p.4 -The Beginning: http://quarknet.fnal.gov/eeu/bigbang.jpg p.5 -Events of the Big Bang: http://www.lpl.arizona.edu/undergrad/classes/ spring2009/Hubbard_206-2/Lectures1/Sun_and_earth.jpg p.6- Matter: http://www.grc.nasa.gov/WWW/K-12/airplane/Images/state.gif p.7- Energy: http://www.lcse.umn.edu/specs/labs/images/spectrum.gif p.8- Universal Expansion: http://media.giantbomb.com/ uploads/0/8184/212175-universal_expansion_large.jpg p.9- Human understanding: http://sankofa.loc.edu/savur/web/Hubble.jpeg p.10- Hoag’s Object- http://upload.wikimedia.org/wikipedia/commons/d/da/ Hoag%27s_object.jpg p.10- Sombero Galaxy- http://en.wikipedia.org/wiki/ File:M104_ngc4594_sombrero_galaxy_hi-res.jpg p.10- Colliding Spirals- http://apod.nasa.gov/apod/image/0807/ ngc5426_gemini_big.jpg p.11- Galaxy Formation: http://en.wikipedia.org/wiki/Galaxy#Evolution p.12- Black Hole- http://astrofacts.files.wordpress.com/2009/07/rouge-blackhole.jpg p.13- Galactic Interaction- http://en.wikipedia.org/wiki/File:NGC4676.jpg p.14- Galactic Interaction (continued)- http://www.nullsession.net/wp-content/ uploads/2009/05/galacticcan.jpg 29 30 Image credits p.15- Supernovae- http://en.wikipedia.org/wiki/File:Keplers_supernova.jpg p.16- Spiral galaxies- http://www.kaheel7.com/userimages/barred-spiral-galaxy.jpg p.17- Elliptical Galaxy- http://apod.nasa.gov/apod/image/0605/m87_gendler_f.jpg p.18- Lenticular galaxy- http://en.wikipedia.org/wiki/File:File-Ngc5866_hst_big.png p.19- Dwarf Galaxy- http://www.mindspring.com/~dhanon/m81p2wsp.jpg p.20- Irregular Galaxies- http://en.wikipedia.org/wiki/File:Antennae_galaxies_xl.jpg p.21- The Sun-http://www.cosmosmagazine.com/files/imagecache/news/files/ SolarFlare1.jpg p.22- http://physics.uwyo.edu/~chip/misc/pics/M16Full.jpg p.23- Hertzsprung-Russell Diagram—http://www.enchantedlearning.com/hgifs/ HRdiagram.GIF p.24- Neutron Star—http://causewehaveto.com/070820_neutron_star_02.jpg p.25- Solar System—http://universe-review.ca/I07-02-SolarSystem.jpg p.25- Planetary Systems—http://spacespin.org/images/articles/81062-closestplanetary-system-hosts_2.jpg p.25- Blue Binary System -http://www.nasa.gov/centers/goddard/images/ content/177768main_O_Star_Binary_med.jpg p.25- Binary System—http://images.astronet.ru/pubd/2006/07/27/0001214984/ rsoph_pparc.jpg p.25- http://www.spaceandtechnology.com/750px-HD_98800.jpg p.25- http://science.nasa.gov/media/medialibrary/2010/03/31/v838monocerotis.jpg/ image_thumb 30