Chapters Nineteen and Twenty

Chapter Nineteen: Nineteen discusses the topic of settling other planets and in particular, making asteroids suitable for human life. The problem with asteroids are that they have very little gravity compared to planets. If we were able to make an atmosphere for this asteroid, it would not be held by its small gravity and be lost in space. An idea by a writer named Jack Williamson seemed very interesting. He suggested a type of paragravity, or an artificial gravity constructed by humans. So far, this is impossible to us, but maybe not in the future. Another more attainable idea is to live inside an asteroid. If we found the right type of asteroid, there would be many different kinds of materials inside it to use for building stone and metal, as well as a source of water in the asteroid. This idea can't be executed today, but this is a project surely possible in the near future, unlike paragravity. A source of power would be needed for this asteroid home to propel it. In this case, Williamson suggested anti-matter. Anti-matter can be explained using a hydrogen atom. In a normal one, there is a positive proton and negative electron. In a anti-hydrogen, the electron is positive and the proton is negative. In fact, we can already make anti-matter. It is formed from the reactions in nuclear accelerators. The problem with anti-matter is that, when contacted with our normal matter, both are annihilated. The reason we have matter and not anti-matter is that when this enormous reaction occurred, some matter was left over or as Albert Einstein said "Matter won".
Chapter Twenty: When you think about it, we actually do live in darkness. Its not what you're thinking though. You can look around at this moment and easily find a source of light. But the Universe is dark, and we are surrounded by it. Alien life could be out there, and it probably is, but we don't know yet. However, a underrated technology by you is actually very useful to science. Radio. This technology could be used all across the Galaxy. If anything is out there, we could possibly communicate with it, if it was as advanced as us or ever more so. The program that is searching for life is the Search for Extraterrestrial Intelligence (SETI). Their first exploration for life was when Frank Drake of the National Radio Astronomy Observatory listened to two stars at a time length of two weeks that were about 12 light years away from us (around 70 trillion miles).  Later on project META was begun. It stands for "Megachannel ExtraTerrestrial Assay". It consisted of 8.4 million frequencies devoted to a single purpose: Alien life. It was designed to distinguish any Earth interfering radio waves from actual waves coming from space. If we are going to search for life, this META project is a good addition.
https://www.youtube.com/watch?v=al7sFP4C2TY

Chapters Seventeen and Eighteen

Chapter Seventeen: Chapter 17 begins with Galileo's first look at Saturn. To him, it appeared he was looking at a planet with "handles". But what were they?  Unfortunately, he would never know. These handles were discovered to be a set of rings made of a range of small rocks. These rings are held to their orbits by Saturn's massive gravity. Saturn isn't the only planet to have rings, Jupiter, Uranus, and Neptune also have rings. Each planet's rings are made of different materials. Jupiter's rings consist of tiny, dark particles. Uranus's rings are made of carbon as well as other organic molecules. We aren't exactly sure how rings form around planets, but there are a few ideas floating around. One is that if two planets come close together, one can be ripped to shreds by the other's gravitational pull if it is strong enough. Another idea is that when planets impact with each other, the moons are destroyed and pieces from the collision form rings. By now you probably know about craters and how they are formed. When two bodies crash into each other, the smaller one leaves a huge hole of impact in the other. This is how the moon formed. A huge body crashed into Earth about 4.5 billion years ago. Lots of chunks of Earth entered space and in turn got caught in Earth's gravity. Over a long period of time, they recombined to form the moon we know today.
Chapter Eighteen: Have you ever thought back about the asteroid that collided with Earth long ago? did this ever make you think that one day it could happen again? It is possible. We have been hit by small bodies before, but they have done noting serious to our planet. To really cause devastation to the human civilization, you would need a body at least a few hundred meters across. On estimate, these types of collisions occur to Earth every 200,000 years, so its almost safe to say were are in the clear for a while. Currently, we are working on ways to monitor bodies that could possibly crash into Earth and ultimately, how to prevent these collisions if possible. Two ideas are circling around to prevent a on course collision with an asteroid. One is to use nuclear powered weapons to blow the asteroid to bits, so smaller pieces would burn up in Earth's atmosphere. A different approach also involves nuclear weapons but for a different purpose. If a body were to happen to set a course for Earth, we could possibly explode nuclear weapons near it, hopefully changing its course elsewhere. This really depends on the composition of the asteroid and how it is held together as well as obviously size. If it is held loosely, then smaller large parts, after explosion, would have a larger chance of impacting Earth. This is currently in the works, so hopefully we discover a method soon.

Chapters Fifteen and Sixteen

Chapter Fifteen: The 15 chapter talks about Mars in specific. It is the planet with the closest climate to Earth and one of the only celestial bodies we have successfully visited. There have been two real, successful missions to this planet and they were mad by Mariner 9 in the year 1971 and by Viking 1 and 2 in the year 1976. They discovered some major geological features of Mars such as a mountain three times the height of Everest and a rift valley that in comparison to Earth, would span the length of New York to San Francisco. The water that once hosted the original life on Earth could have existed on Mars and, just maybe, there could have been a brief period of life. Meteorites are good history tellers to us. They have been found in Antarctica, preserved by the ice and snow. Some of these have been analyzed and found to be from Mars. In these fragments, there is evidence to show that they had been in water at one time. If water had existed on Mars, then it is very plausible to question if life had once existed there. Long ago, Earth and Mars were both planets with water, so could Mars be hiding miniscule life deep within it?
Chapter 16: This chapter poses a great question: Should we spend the money to make a human trip to Mars? The problem Sagan proposes is this: for the expense of a trip such as that, we could save so many starving and impoverished peoples' lives. Is it right that we stay within Earth, or is it right that we expand into space? Our history could have taken so many different paths. if we had stuck with and expanded the manned space program, could we have already been living on distant bodies such as asteroids, the Moon, or even Mars? President George Bush wanted to initiate this, so on July 20, 1989 he announced the Space Exploration Initiative (SEI). This program set up a series of space triumphs until 2019, which would be the crowning achievement of sending humans to Mars. Many problems arose however, such as the timeframe being longer then Bush's presidency, leaving the program to his successors. Another major problem was the cost of the trip. Many different prices were estimated, but a clear plan wasn't conceived.

Chapters Thirteen and Fourteen

Chapter Thirteen: Chapter 13 talks about the moon. The first men to land on the moon, Neil Armstrong and Buzz Aldrin, did so on July 20, 1969 in the famous Apollo 11 spacecraft. It was a historic and hard-won step for mankind. The moon has been there for us since the beginning of the Earth. It has held just as much mystery and fame as the planets in our solar system. The word month and Monday come from being named after the moon. But what was really the significance of the Moon to humans back then? It was used as a sort of metaphor for the unattainable. No one had even conceived a way to reach the moon, until the Apollo Space Program was developed. From this another question arises, was the space program really a scientific deal, or was it something else? President Kennedy was the one who helped to start the program, but initially not for science. He wanted to prove a point to the world, not to join the Soviet Union at the time. So that means it was more of a political program rather then for the good of science. To reach the moon, you would need large, powerful rockets. These rockets that were used could also serve as nuclear weapons. This was a demonstration of power by the United States.
Chapter Fourteen: Just imagine what it would be like to see the Earth from Space. Would you see rival nations or perhaps enormous cities? Probably not unless you have a very advanced optical device. Our technology developments have granted us immense power, but it will amount to nothing if we don't preserve our world. This resembles the famous quote "with power comes responsibility". We have the power, but not the responsibility. Our affect on the Earth is beginning to show. The ozone is depleting, ecosystems are being polluted and destroyed, and the global climate is changing. Robert Goddard, a space flight pioneer, introduced comparative planetology. You can look and compare other worlds to Earth and see how they are different. If another planet has to much of a specific element, you can see what the result would be. This is basically showing us what not to have happen on Earth. There are three main threats to the Earth: "ozone depletion, greenhouse warming, and nuclear winter".

Chapters Eleven and Twelve

Chapter Eleven:
Chapter 11 begins with the mystery of Venus. Long before we knew that Venus was a planet, people referred to it as the evening and morning star. When telescopes were invented, it was discovered to be a planet. Venus is a tough planet to look at because it is covered in a thick cloud of sulfuric acid. In fact, there are no breaks in this acid atmosphere to even see Venus's surface. All light that is shown on Venus just gets scattered. A technique that did prove to be effective was the use of radar to map Venus's landscape. The radar waves bounced off the surface and were returned and thus interpreted by the amount of time it took for the wave to return. The start of this exploration of Venus was due to Mariner 2 spacecraft. It gave us some of the first radio data as well as observing the clouds in the infrared spectrum. You could say that it is the tool of astronomy that brought about the exploration of planets. Today, it orbits the sun and will continue to do so.
Chapter Twelve:
Twelve beings with a topic that has always fascinated me: Volcanos. These enormous pits of lava resemble mountains and can be lush environments for many animals and plants. However, they can also cause mass amounts of destruction at any time. The crater of the volcano is called the caldera. One of the most famous eruptions was Mt. Vesuvius, which destroyed Pompeii. Another reference to the ancient gods, volcanos were named after Vulcan, a Roman god. Underneath volcanos are pits of volcanic rock, melted into the lava that is spewed out at about 1000 degrees Celsius. Volcanos tend to form in areas were to plates come together. But why is the Earth's core so hot? There are two parts. Radioactive elements produce heat as they decay and Earth still holds some of the "original heat" from when it was formed. This is what cases the lava to heat up so much. Volcanos are formed from countless lava spews until the lava can no longer reach to top of the volcano.

Chapters Nine and Ten

Chapter Nine:
Chapter nine begins with the final stop of Voyager 2. Neptune is a very mysterious planet because it is so far away from us. To help get a grasp for the distance of Neptune, you can think of it in terms of its orbit around the sun. Since being discovered in 1846, Neptune has yet to complete a full orbit around the sun! It is known as a Neptunian year. Light from Neptune takes a long five hours just to reach us here at Earth. Neptune is one of the four gas giants along with Jupiter, Saturn, and Uranus. At its center is a rocky and cold world, but it gets its size from its enormous atmospheres around it. You can't even see its core from the outside of it. Its atmosphere consists of hydrogen, helium, and a bit of methane. Like Saturn, Neptune is surrounded by rings. Neptune's largest moon is Triton, which also has a relatively long orbit. It takes the equivalent of six days on Earth to make one orbit around Neptune.
Chapter Ten:
Chapter ten starts with the sky. Ever wonder why the ski is blue? It is something that we take for granted but actually don't know that much about it. Other worlds have yellow or even green skies. I couldn't even imagine that. Back in the August of 1957, David Simons became the highest human being in the world. He flew a balloon above 100,000 feet in the air. When he looked down at our "blue" sky, he described it to be a "dark, deep purple". The blue that we see is sunlight being reflected by air particles. When sunlight reaches the atmosphere, it gets bounced around. This is called scattering. Blue and violet colors are more energy and get scattered more effectively.

Chapters Seven and Eight

Chapter Seven: The seventh chapter starts off with the topic of the origin of life on Earth. Scientists today are attempting to re-create the conditions in which living organisms arose and how they evolved into modern life. The first creatures had to have been small microorganisms that lived in a very hydrogen rich environment. There was not much oxygen back then because plants had not yet arisen. These organisms then started to evolve through Charles Darwin's process of natural selection. For these organisms to survive, the basic organic building blocks of life had to be present: amino acids and nucleotide bases.
Chapter Eight: Chapter eights begins with talking about the immense sky and of the stars. The night sky is like an enormous clock, everything moving on its scale. Our ancient ancestors observed this, totally amazed by it. they named the planets after their gods and used the sky as a clock for everyday. An interesting fact, the names of every day of the week derive from ancient civilizations beliefs in their gods. For example, Saturday is named after the Greek God Saturn. Around that time there were six planets that were known. But in 1781, another planet was discovered. A musician named William Herschel had discovered Uranus, which was named after the father of Saturn.

Uranus