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The Basics of the Universe Table of Contents Introduction………………………...……1 The Beginning……..……...……..………2 A starter’s guide to the cosmos Our Place in the Universe……….………3 By: Aashish Bharadwaj The Sun…………………………….……7 Our Solar System………………….…….4 Comets…………………………….…….9 Meteoroids…………………………...…10 Asteroids………………………….…….11 Lifetime of a Star…………………….…12 Neutron Stars……………………….…..14 Extraterrestrial Life………………….…17 The Oddities and the Normalities...........18 Our Future………………………….…..19 Space Records……………………….....20 Fun Facts………………………….……22 Glossary……………………...…….…..23 Introduction The Beginning Have you ever looked up at the sky and wondered, “Where are we? How did we get here? When did it begin? Why did it happen this way?” If you have, then this is the book to read. If you would like something more advanced, then I would suggest reading a book by Brian Greene or watching “The Universe,” a series created by History Channel. The start of everything was about 15 billion years ago. Most scientists agree on a theory called the ‘Big Bang’. They came up with this theory using their knowledge of the universe. The universe is expanding, so it would be contracting if you were to view time in reverse. Eventually, everything would be the size of a tiny neutron that has planc length1 and contains planc energy2. The start of time would be when this neutron suddenly expands. It would be very silent since there is no air in space to carry sound waves. Within the first second, molecules would have formed, hydrogen being the most abundant. In a year, you would start to see solids starting to form. In a million, stars would begin their violent lives. In 2-3 billion, stars would clump together to form galaxies. In 10 billion, the Sun would have formed. In another 0.5 billion, the Earth would said hello. Wait another 4.5 billion years, and you would see yourself. This is the timeline of the universe. It is everything in existence, from stars to this book. 2 1 1 2 10-32 Energy required to have 11 dimensions according to string theory Our Place in the Universe Our Solar System How big are the cosmos? How old are we? First, let us discuss size. Earth has a diameter of 8,000 miles and a 2dimensional circumference of roughly 25,000 miles. If you were to travel the diameter of the Earth in a car with unlimited fuel, then you would take about 8,000 minutes, or 5 to 6 days! Thu Sun is about 93 million miles away from us, and the next closest star is system is Proxima Centauri, Beta Centauri, and Alpha Centauri, which is 4.3 light years away. A light-year is not a measurement of time, but instead distance. Light travel 186,000 miles per second. Multiply by the amount of seconds in a year to obtain the distance of a light-year. At this speed, you could travel around the Earth 7.5 times a second! Our galaxy is about 100,000 light years across. The galaxy that is nearest to us is Andromeda, which is 2,500,000 light-years away! The viewable universe is trillions of years across, yet is bigger than just what we see through our telescopes! There are quadrillions of stars in the universe. Thu Sun is in the Orion Arm of our galaxy – The Milky Way, which is in the Local Group. (galaxy cluster.). This is part of a supercluster, which is a part of the universe. There are trillions of superclusters in the universe. If this makes you feel insignificant, then knowing that the rate of expansion - known as inflation – is accelerating will make you sick. Do you want to feel even smaller? If you do, then read on! If the entire life of the universe could be put in a 24-hour day, then you humans would arrive during the last few seconds! Even though all of this is true, I still feel quite large. Our atoms have come from exploding stars, so I feel as if I am a part of the universe, instead of in it. Our solar system consists of many bodies that orbit the Sun, which is our life-giving star. Here is a list of the bodies in it. Inner Solar System Mercury: The temperature ranges from -200 to 500o F. This is because it has a very thin atmosphere since it is small, therefore not trapping any heat in. It has zero moons, and many craters. It has a year of 88 Earth-days because it is so close to the Sun, only an average of 56 million miles away. This may seem to be huge, but it is not compared to the other planets. Its day is 58 Earthdays, but it actually seems to take 176 Earth days instead of 58 because of its orbit! Venus: This planet was named for the Roman Goddess of Love and Beauty, but it is anything but lovely. Temperatures soar to 900o F. This is because it has a very thick atmosphere. It has a double hurricane system, which is the system of the two hurricanes at its poles. This is a result of the planet constantly trying to cool itself off. Venus is 67 million miles away from the Sun. It has a year of 224 Earth-days, but a day of 243 Earth-days! The size of Venus is barely smaller than that of the Earth, so it is known as ‘Earth’s sister’. It is visible in the sky with the naked eye. It has no moons. Earth: This is our home planet. It is known as the ‘Blue Planet’ because of its many oceans. It is the first planet to have a moon, known as The Moon. Its actual name is ‘Luna’. Mars: Named after the Roman God of War, this planet is red due to its dusty terrain that has gone through oxidation. Mars is about half of the size of the Earth, and has a thin atmosphere. There is ice scattered around the planet. Two rovers, named Opportunity and Spirit, have roamed the landscape, searching for signs of life. So far, none has been found, even though they have searched for many sols.3 Mars is 146 million miles away from the Sun, and has a year of about 687 Earth-days. Its day is barely longer than Earth’s. The average temperature is -81o. Asteroid Belt: This not a planet, but instead a belt of asteroids that are orbiting the Sun. There are millions of asteroids in it, some of which have their own moons. Uranus: A light blue gas giant that has a 98o axial tilt. This means that its glowing rings are almost orbiting vertically. Its magnetic field has a tilt of 60o. It has its own big storm called The Great Blue Spot. Uranus is nearly 32,000 miles in diameter. Each day is 18 Earth-hours, and each year is 84 Earth-years. It is 1.8 billion miles away from the Sun, and has nearly 40 moons. Neptune: A dark blue, extremely windy gas giant. It has a very mobile storm that is called The Great Dark Spot. It is titled ‘The Windy Planet’. It has a few rings, and about 35 moons. It is about 30,000 miles in diameter. A year is 165 Earth-years, and a day is 20 Earth-hours. Past the Outer Planets Outer Solar System Jupiter: A huge gas giant that rotates in just nine Earth-days, and orbits the Sun in 12 Earth years. It has a storm 2.5 times the size of the Earth, known as the Great Red Spot. It has rings that are barely visible and nearly 80 moons. It has a diameter of 88,700 miles, and is 480 million miles away from the Sun. Saturn: A very light gas giant that is known well for its rings, which Galileo Galilei4 mistook for ears. Saturn has a storm known as The Great White Spot. A day on Saturn is 10 Earth-days, and a year is equivalent to 30 Earth-years. It has nearly 70 moons, and is 883.5 million miles away from the Sun. It is the last planet that can be seen in the sky with the naked eye. Pluto: A dwarf planet that has no atmosphere and three moons, one of which is so big relative to the size of Pluto that they are a like a binary system5. It has a very eccentric orbit that crosses Neptune’s orbit. It has a surface temperature of -400o. Kuiper Belt: A belt of comets and dwarf planets. Oort Cloud: Dusty sphere surrounding the Sun at a very great distance. Nemesis: A theoretical brown dwarf, or failed star, that mysteriously orbits the Sun beyond the Oort Cloud. 6 3 4 Martian days ancient Italian astronomer 5 A system where two bodies orbit each other The Sun more violent. The Sun has lived for 5 billion years, and has another 5 billion years to go. In about 4 billion years, the Sun will Our star is the main reason for our existence. At the center of the Solar System, we would not have light, heat, seasons, or even life. It is a yellow-dwarf, has a surface temperature of 10,000o F, and fuses 6 billion tons of hydrogen to helium per second! One second of this power could supply California for an entire week. Even though this is true, it is in-fact a relatively cool star when compared to others. At a distance of 93 million miles from the Earth, or one AU, (Astronomical Unit), it takes 8 minutes for its light to reach us. The Sun can fit a million Earthsized inside of itself. It has dark spots called Sunspots. These are regions where less heat is emitted. Also in these areas are highly magnetic disturbances that can cause Solar Prominences, loops protruding from the Sun that can last for days. These are multiple times the size of the Earth. run out of hydrogen, and will be left with helium. It will begin to fuse it, growing in size and swallowing up Mercury, Venus, and turning Earth into a soup. It will become a red giant, and have a hotter core, but a cooler surface. This stage will not last very long because the great energy that it will produce will also cause it to release its outer layers, creating a nebula. A white dwarf will remain, which will then later turn into a black dwarf. Prominence Sun The Sun slowly rotates at different speeds in different area. This is possible because it is a ball of plasma. The Earth faces a group of Sunspots every few years. Solar wind is blown, which hits the Earth and causes an Aurora. These can interfere with electronics and electromagnetic devices and appliances. When the Earth is closest in its orbit to the Sun, and the Sunspots are facing its way, the electromagnetic storms produced can be violent. As the Sun grows older, these storms will grow even 8 Comets Meteoroids A comet is also known as a ‘dirty snowball.’ It is made of ice and dust, but not ice from just water. It is a mixture of many different cold solids. In our solar system, comets reside in the Kuiper Belt and the Oort Cloud. Some leave these places and make a very eccentric and elliptical orbit around the Sun, which blows wind at them, thereby causing them to have tails that can be millions of miles long. Have you ever seen a meteor shower? These are caused by meteors falling towards the Earth. Meteors are rocks that have entered the Earth’s atmosphere. At least one million hit the Earth. These are called meteorites. When these rocks are in space, they are called meteoroids. As meteors fall towards the Earth, they burn up in the atmosphere. They are usually 1-100 ft in size, and wander around randomly in space. If you think that you will forget the difference between the three types, then this is for you. Tail Nucleus Comets appear as bright streaks in the sky, and remain there for many months. They glow due to the ions6 that are charged there. When the comets have passed the Sun and gone to the other half of its orbit, they will appear to move backwards. Some comets that elect to either commit suicide, or be roasted by the Sun are called Sungrazers. These either hit the Sun or come very close to it. Mete’roid’ – ‘void’ of space Me’teor’ – ‘tear’ of Earth Meteo’rite’ – ‘site’ of an impact 9 10 6 Ionized particles Asteroids Lifetime of a Star Big space rocks are called asteroids, ranging from 1-100 miles in diameter! They mainly call the asteroid belt their home, but some have irregular orbits. Some are even so big that they have mini asteroid-satellites (another name for a moon) orbiting them! Asteroids have been known to impact the Earth. One asteroid that was about 15 ft in diameter created the Arizona crater, and another caused the extinction of the dinosaurs when it struck the Yucatán (Yucatan) Peninsula 65 million years ago. Infact, many asteroids bombarded the Earth when it was in its infancy, causing it to grow larger. Reading the next part may ALARM you. The life of a star is very violent. A star is a ball of plasma that fuses matter and releases a lot of energy in the process. Let us take three different stars as an example. A particular asteroid by the name of Apophis will come closer to the Earth than our geostationary satellites are to it on April 13, 2029. It can in even be seen in the sky with naked eye. If it passes over a 5-mile wide weakness in the Earth’s gravitational field, then it will come back to hit us in 2042. The chances of this are very small, but substantial enough to cause uncertainty. Star A: Low mass, red dwarf star. A red dwarf is a relatively smaller star, glowing red in color. It continues to do so for trillions of years, since it does not burn fuel rapidly. Star B: Medium mass star that is a bright yellow, about 1.5 times the mass of the Sun. Formed from a protostar made of gases from a previous massive star, it burns for 10 billion years before swelling into a blue giant. It fuses many elements before creating its own nebula. It turns into a white dwarf, emanating its remaining energy. Then, it becomes a black dwarf. Star C: High mass star, blue and big, with 100 solar masses. This star fuses many elements in the periodic table, but for a VERY short period of time. It eventually bloats into a blue supergiant, fusing molecules to make iron. This element is poison, since fusing it does not produce any energy. Within a matter of seconds, the star, which is billions of miles across, collapses on itself. Its outer layer bounces off its core and blasts into outer space in the biggest explosion known to man. This is a supernova, and it releases more energy than the Sun will produce in its entire lifetime. After this, it releases two bursts of gamma rays 7 at its 11 7 Strongest wave in the electromagnetic spectrum poles, destroying anything in its path. What remains is a neutron star. You will learn more about these in the next chapter. 13 Neutron Stars After a supernova, a neutron star is leftover. It is the core of the previous star, and does not sustain nuclear fusion. They are very dense because the atoms are compressed to such an extent that only the nuclei are left, since the lack of fusion allows gravity to crush it. In fact, the size of the star is so small now that it can be compared with that of the Earth, and one bucketful of its material - assuming that we can obtain any - has as much mass as Mount Everest. Some of these are called magnetars, while others are called pulsars. Neutron stars spin very rapidly, and this causes them to have very strong magnetic fields, and the ones with the strongest are called magnetars. Pulsars have two light beams (not harmful at a distance) that emit out of their polar regions, and if these are facing Earth, then the star appears to blink very quickly, hundreds to thousands of times per second! Finally, there is one more type: A black hole. These monsters can only be created by an extremely massive supernova. (Some call it a hypernova) These are so densely packed at a single point that the resulting gravity produced at that point stops even light from escaping past the event horizon – the point of no return. Black holes are literally holes in space, and cannot be seen. We know that they exist because of its effects on surrounding matter. In fact, it is thought that there is a supermassive black hole at the center of our galaxy, and most other galaxies as well, orbiting it. The material spiraling around a black hole is called the accretion disk, and if you were to look at the inner edges, then you would just see warped colors. In the center is the singularity, which is the point of infinite density. These will gobble up matter and add to the size of the black hole. At this point, time is nearly at a standstill, (a very confusing concept to explain) and all of Einstein’s equations fail because they end in “cannot divide by zero” error. Event Horizon affect life as we know it, and you are about to learn about life away from Earth. Everything that there is to know about black holes cannot be told because all of that was barely skimming the surface! A whole series could be written about the monsters of the universe. Singularity Accretion Disk Since the gravity is much greater at the singularity than it is at the event horizon, (because of the concentrated gravity) anything that was to fall into it would be spaghettified, a term used to describe the process of entering a black hole. It would be stretched apart, including the atoms! Even though you cannot see these atoms, you may see them with other matter if they are ejected out at the poles. Black holes that do this are called quasars, ejecting matter because they took in too much at once. These beams are VERY hot, and slightly cool down as they fly through space. They could 16 Extraterrestrial Life The Oddities and the Normalities E.T. is short for extra-terrestrial, which means ‘away from territory.’ When you add ‘life’ to it, it becomes ‘aliens,’ which almost certainly exist. It is not a matter of belief, but instead of scientific probability. In the vastness of space, it is almost inevitable that another planet like ours exists. Astronomers have already discovered many planets orbiting stars like our own, and a particular few have caught their attention. In addition, they have received a short radio signal called the WOW signal. It was rhythmic, but was never heard again. Our closest hope to discovering aliens is on Jupiter’s moon, Europa. It has an atmosphere and water. Since life as we know it must have water, this would be a good place to look at. The only obstacle is the temperature, which is well below zero. Another place to look is on Titon, the 2nd largest moon in our solar system, and Saturn’s greatest. It has liquid nitrogen, but life could possibly live off it. In fact, life may even inhale gas to quench its thirst! Even though we may be able to find some, it may be a bad idea, according to Stephen Hawking8. He says, “If we were to find life forms, then one of us would be like Christopher Columbus, who did not treat the Native-Americans very well at all. What is normal and what is odd? For one thing, we ourselves are not normal. Neither is our Sun, because most stars orbit other stars in binary systems, suggesting that most dots in the sky are actually two dots that may or may not eclipse each other, like our Moon’s eclipses, which are also odd. Additionally, the size of the Sun is relatively small compared to those of most other stars, since it is only a yellow-dwarf. Looking farther out, Saturn has a perfectly formed hexagonal storm at its northern polar regional area. It is dark brown, whereas the rest of the planet is white. A normality is nebulas filled ethyl alcohol, which we drink! Even further are three black holes orbiting each other. If they were to collide, then gravitational waves would be sent out. 17 8 A world famous astrophysicist who is well known for his theory of radiation from black holes that is emitted due to feedback. It is called ‘Hawking Radiation.’ He is physically disabled and needs a computer to talk for him. 18 Our Future Space Records The biggest question is about our future. What awaits us? The first scientific theory that came out was called “The Big Crunch.” In this, gravity makes everything smash together. It was recently discredited due to the discovery of the acceleration of the rate of the expansion of the universe, which puzzled scientists, since it would be like tossing an atom up and seeing it accelerate upwards! A new one is “The Big Freeze,” which states that the universe will expand forever and die in cold. An unlikely theory is called “The Big Rip,” which states that everything will tear to pieces. The Big Freeze is the most widely accepted theory, which is based on the second law of thermodynamics, which states that everything must rot. Do not worry though, because it will be in trillions of years. Biggest Moon in Solar System = Ganymede, which belongs to Jupiter and has a 3,269 mile diameter. Biggest Planet in Solar System = Jupiter, which is 318 times the mass of the Earth. Fastest Orbit in Solar System = Mercury, at 88 Earth-days. Fastest Orbit in Solar System = Neptune, at 165 Earth days. Brightest Star in Night Sky = Sirius A, which is 8.6 light-years away. It is a giant white star with a white dwarf companion called Sirius B. Fastest Winds in Solar System = Neptune’s, with speeds of up to 1,250 mph. Most Powerful Explosion = Supernova, which releases more energy than the Sun will release in its entire lifetime. Slowest Rotation in Solar System = Venus’s, with 243 Earth days and retrograde9 rotation. Shortest Rotational Period in Solar System = Jupiter’s, which is 9.84 Earth hours. Biggest Volcano in Solar System = Olympus Mons, an extinct volcano on Mars, which is 3 times the size of Mount Everest. Biggest Canyon in Solar System = Valles Marineris on Mars, which is 5 times the size of The Grand Canyon. 19 9 Clockwise Least Dense Planet in our Solar System = Saturn, with 0.93% the density of water. Most Visible Planet in Sky = Venus Hottest Planet in Solar System = Venus, with a surface temperature of about 896o Fahrenheit. Fun Facts Venus goes through phases like the Moon. Mercury was named after he messenger of Roman Gods. Mercury’s craters are named after famous people like Mozart. Edmond Halley was the first person to predict the appearance of a comet. Neptune was not found, it was calculated. Mars was named after the Roman God of War due to its red appearance. Jupiter was named after the King of Romans Gods. Brown dwarves have iron precipitation, which falls at an extremely high speed. The moons of Uranus are named after characters in Shakespeare’s plays, such as Juliet. Neptune is named after the Roman God of the Sea. Venus was named after the Roman God of Love and Beauty. Saturn was named after the Roman God of Agriculture. 21 Planet means wanderer in Greek. The biggest star ever discovered is one million times the mass of the Sun. Glossary Accretion Disk: Disk of material that orbits a black hole. Asteroid: Big space rock. Binary System: System of two stars that orbit each other. Black Dwarf: Dead core of a star that lets off no energy. Black Hole: Remnants of a dead star that exploded in a hypernova, creating a point of space that is so dense that light cannot escape its gravity. Blue Giant: Giant blue star. Blue Supergiant: Very giant blue star that is near the end of its life. 23 Brown Dwarf: Failed star. Comet: Icy rock that leaves off a tail when it approaches a star. Gas Giant: Relatively big planet that is composed of only gas and has no solid surface. Inflation: Rate of expansion of the universe. Dwarf Planet: A massive body that is too small to be considered as a planet. Light Year: Distance that light travels in a year, about 6,000,000,000,000 miles. E.T.: Short for “extraterrestrial.” Magnetar: Neutron star with very strong magnetic field. Event Horizon: Boundary past which light cannot escape. Meteor: Falling space Rock. Extra-terrestrial: Away from territory. Meteorite: Space rock that has impacted a planet. Event Horizon: Boundary past which light cannot escape. Meteoroid: Small space rock. Moon: Satellite, or small object, that orbits a planet. Galaxy: Big group of stars that usually has a black hole at its center. Nebula: Giant cloud of gas in space. Galaxy Cluster: Group of galaxies. Neutron Star: Star that is so dense that the atoms are squeezed into nuclei. Orbit: Path around an object. Solar Mass: Mass of one Sun. Used for comparison. Planet: Big object in space that usually orbits a star. Solar System: System of a star and planets Protostar: Star that is in its early stages. Solar Wind: Particles thrown by the Sun. Pulsar: Neutron star that appears to pulse because two beams are emitted from the poles. Star: Giant ball of plasma that sustains nuclear fusion. Supercluster: Group of galaxy clusters. Quasar: Black hole that spews out matter from its poles. Red Dwarf: Small red stars that shine for trillions of years. Red Giant: Giant, dying, red star. Rings: Tons of space rocks that orbit a planet. Satellite: Body that orbits a mass. Singularity: Point of infinite density. Supernova: Giant explosion that is caused by a dying supermassive star. Universe: Everything in existence.