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Standing on the Shoulders of Giants

“We are a way for the Cosmos to know itself,” said Carl Sagan.  Astronomy is not only the oldest science, but also a window through which mankind peers through in attempt to glimpse the fleeting answers to our deepest and most fundamental questions. As a direct result of the this class, I find myself looking skyward more often at night. I spy Jupiter and Mars, both high in the sky this time of year, and I can understand their significance in our holistic picture of not only the Solar System, but the Universe itself. It’s a bit eerie to gaze upon Mars and remember that Tycho Brahe stared endlessly at the same red dot of light night after night, meticulously recording its position and compiling decades of data points all so that his young assistant, Kepler, could use the data and Mars’ convenient relatively high eccentricity to derive his three laws of planetary motion. These laws were revolutionary and forever changed the way we perceive the Universe. Kepler spent his life’s work digging through data tables to come up with what has become a paragraph or two in an astronomy textbook which anyone can read and understand with ease. Progress marches on and new discoveries reveal more than anyone could have even imagined. 15 years ago exoplanets were thought to be probable, but there was no proof. Today astronomers are finding more and more that they seem mundane. Newton said of his discoveries, “If I have seen further it is by standing on the shoulders of giants.” No such truer statement rings across time: we have only come as far as we have in our understandings of the cosmos through the work of those who came before. Come another decade the universe may look very different than it does today; as we discover more among the heavens and widen our field of view, the universe gets smaller and closer to home.

 

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Are We Alone?

The famous science fiction writer Arthur C. Clarke was quoted as saying, “Two possibilities exist: either we are alone in the Universe or we are not. Both are equally terrifying.” A truer statement is hard to come by. Yet quote also sparks tremendous debate and intrigue among those whose ears come across it for the first time. We all wonder, are we reallyalone? Could we possibly be all that is out there? Is there truly no one looking back, wondering the same? Such questions have teased all of mankind, from our smartest scientists to the youngest of children and their endless curiosity. It is part of what makes us human, that we search for more than we just perceive around us. But perhaps there is a slightly more answerable question, can we quantify the possibility of life?

The answer is yes (and no). No we cannot provide hard numbers to a computer and have it spit out an answer which determines if there is life elsewhere in the universe, but yes we can get reasonable estimates. That is where the Drake Equation enters play. Postulated by Frank Drake back in 1961, the equation is an attempt to quantify, to our best estimates, the possibility of an intelligent civilization somewhere in our Milky Way Galaxy. By multiplying the estimated percentages of factors which we believe contribute to the possibility of intelligent life, and then multiplying that fraction by the total number of stars in the galaxy, out comes a simple number which guesses at the number of intelligent alien civilizations which we could theoretically make contact with. The factors of the Drake Equation include: the average rate of star formation in the galaxy, the fraction of those stars that have planets, the average number of planets per star that could potentially support life, the fraction of those planets that actually support life, the fraction of life-bearing planets with an intelligent species, the fraction of intelligent species that could develop technology to communicate across the cosmos, and finally, the length of time the average civilization lives. The first three fractions are the only ones which we actually have very accurate predictions. They are quantifiable and testable by astronomers. However, the last 4 are essentially just guesses. We may have some reason to set our guess one way or another but at the end of the day, one guess is no better than another. Depending on how one sets these factors, one could get the number of such civilizations to be 1e-10 or 1e4 and anything in between.

We can only speculate on the existence of alien civilizations. The Drake Equation is just a tool to help us along in the process. Nevertheless, considering the vastness of space and the lifetime of humans as individuals and possibly as a species, the chances that we ever make contact with another civilization may be extremely slim, regardless of how abundant life is in our universe. But until the day where either we become intelligent enough to travel these great distances or an alien comes knocking on our door, we may truly never know an answer to humanity’s greatest question… are we alone?

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Science Fiction to Science Fact

It has always been the fantasy of science fiction writers to mine an asteroid for its precious materials. Stories such as Catch that Rabbit by Isaac Asimov, The Rolling Stones by Robert A. Heinlein, and the Heechee stories by Frederik Pohl are among hundreds that feature futuristic mining camps on asteroids. But now humanity has reached the point where we could turn such an idea into a reality. Today, we possess the technology to find, prospect, mine, and bring home precious and rare metals from asteroids in our Solar System. The only reason we are not currently operating these plans is simply money issues. As lucrative as such an operation is, it would be incredibly expensive to start up and very risky to go through with. Nevertheless, there are people who are vocal in their effort to drum up the necessary funds to go through with such an endeavor. One such man is Peter Diamandis, a man who graduated from MIT with a degree in aeronautical/astronautical engineering, and then went to Harvard Medical School. Needless to say, he is an insanely smart individual; but what really sets him apart is his passion for exploring space. He founded a company which he called Planetary Resources, whose sole purpose is to mine asteroids. He headhunted the best NASA scientists and put together one of the most brilliant teams in rocket and rover construction.

Planetary Resources’ plan is actually quite simple. First, find and track “near-Earth” asteroids, which means asteroids which follow orbits that bring them relatively close to Earth (as oppose to those which inhabit the Asteroid Belt beyond Mars’ orbit). Then, send rovers as prospectors to the best asteroid candidates. Then when the go ahead is given, send another spacecraft to gravitationally tug the asteroid into a stable Earth orbit, at which point teams of astronauts can work from the relative safety of low-Earth orbit to extract metals.

In a recent interview on StarTalk Radio with Host Neil DeGrasse Tyson (a podcast/radio show that I highly recommend), Diamandis was asked why he wanted to pursue such a risky business. Diamandis then told the story of aluminum. Aluminum was more rare, and hence more expensive, than gold in the 1800’s. This was because, while aluminum is much more common on Earth than gold, most of Earth’s reserves are chemically locked within the bonds of other rock. At the time, the technology was not there to extract the aluminum ore from those rocks, thus the only ore available was the much rarer pure form. In fact, Diamandis pointed out that in Versailles, the French king’s palace, in the same display case as the crown jewels are two bars of pure aluminum. This is because at the time, aluminum was such a luxury that it was on par with the royal jewels of a great nation. But then, when chemists discovered a method to extract aluminum from rocks, all of a sudden there was so much aluminum that it became near worthless. The prices plummeted as the first law of supply and demand took over. But while this may have been bad for those invested in aluminum, it was vital for new discovery and invention. With the price at pennies, it became economically lucrative to use aluminum in new experiments and inventions, thus ushering in a new age of technological boom based off of aluminum. Now we think so little of the metal that we wrap our sandwiches in it and then throw it away. But that same metal was put on spacecraft, in factory machinery, in pretty much everything that defines the modern world, all because of an influx of supply from technological breakthrough. Diamondis wants to do just that, but with different metals, such as platinum and titanium which are both abundant in asteroids. He wants to lead the way in the search for new technologies based off of currently very expensive materials. Who knows, maybe in the future you will wrap your sandwiches with platinum foil!

Click here to learn more about Planetary Resources and Peter Diamandis.

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Edmond Halley: Proving Newton

Newton was the first to provide a mathematical construct to describe the effects of planetary motion around the Sun. But then the question arose, how could we find evidence for the theory? Stepping up to the plate was the prominent astronomer Edmond Halley. Born in the English countryside on November 8, 1656, Halley was a inquisitive child, always looking up and always asking questions. He grew up to professional pursue his curiosities. In his early 20s he made an expedition to the island of St. Helena in the southern Atlantic in an effort to be the first man to map the southern skies. Little known to Halley, but the weather on this remote island was not favorable to sky viewing as it was often stormy and cloudy. As a result it took him over a year to map the locations of the brightest southern stars. Not only did he contribute to astronomy, but he was also a bit of an inventor: he is responsible for the creation of the diving bell. But anyways, what do diving bells have to do with Newton? Well, nothing really, but it was Halley’s most memorable accomplishment that connects him to Newton. The comet which now bears his name, Halley’s Comet, was one of the first pieces of evidence in favor of Newton’s theory. Although, there is a common misconception that Halley’s name graces the comet because he discovered the comet. This, however, is incorrect; Halley only recognized that the comet he saw in 1682 was the same one seen in prior years by other astronomers. In fact, Halley recognized that the same comet returns to the skies every 76 years, a conclusion he reached by using Newton’s equations and detailed astronomical observations going back hundreds of years. He calculated the orbital trajectory of the comet and predicted it would again return on March 13, 1759 (he was spot on! Even though he didn’t live to see it). With Halley’s correct prediction came definitive proof of the practicality and application of Newton’s law. And as icing on the cake, just like clockwork every 76 years the comet returns to the night sky in a dazzling display of the beauty of the universe. You too can see the comet, but not until July 28, 2061!

To learn more about the comet, check out this video!

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Is There Anybody Out There?

We have always asked the question, “Are we alone in the Universe?” Until now we firmly do not have an answer. But there is a little dreamer kid in all of us, including scientists. Which is why when NASA announced  it would be sending a probe to deep space, they decided to include a message to any extraterrestrials that may come across the probe in the distant future. Pioneer 10 and Pioneer 11, launched in 1972 and 73 respectively, the two probes tasked to set out on this amazing journey, had prime purposes of flying by Jupiter and Saturn (Pioneer 10 only visited Jupiter, while 11 visited both) to take measurements and pictures which would be sent back to Earth. The scientists knew that the Pioneer probes had a one-way ticket from Earth, so they decided as an added bonus that once the encounter with the planets was done, they would maneuver the probes so that they would use their final stop planet as a gravitational slingshot, accelerating the probes to achieve escape velocity from our Solar System. Essentially, we flung them out towards the stars in an attempt to expand Man’s sphere of influence to beyond our lonely Sun’s gravitational system.

But then the question arose, what if, by some small chance, an intelligent alien came across our probe? What would they think? More importantly, what would we want to try to tell them? NASA tasked famed astronomer and cosmologist Carl Sagan with coming up with a plaque to put on the probe. Sagan came up with this image. The highlights of the plaque are both a male and female naked human being, standing side beside and in front of a to scale drawing of the probe itself, so as to give any alien a sense of size. Additionally the man’s hand is raised as a greeting sign, though Sagan admitted that this welcoming sign would most likely not be understood by an alien, though it does provide a sense of how our bodies operate. The most important part of the plaque lies at the top left corner; it is a picture of two hydrogen atoms, one with electron spin up, the other spin down. When an electron goes from spin up to down, there is a very small energy change which releases a photon of wavelength 21 centimeters. This 21 centimeters is a universal measurement, an presuming an intelligent alien, they would know this (perhaps not by the unit centimeters but by their own unit). From this measurement, assigned the binary number 1 as evidenced by the dash between the two atoms and the straight line inscribed there, sets up a binary system which can be used to describe other numbers. This system may not be understood by an alien but it is the best chance we have at a language they would understand. Using the system, we spell out the location of planet Earth in relation to nearby pulsar stars, as evidenced by the lines radiating from a center point at the left of the plaque. Those lines are actually binary codes which describe the period of the stars pulsation and its distance from Earth. An intelligent alien would be able to pick out these stars in its sky and possible use them to find Earth (for our good or for bad is another question! We don’t know if we want them coming to us!). Finally, along the bottom is a rough picture our solar system, with all the planets in order, along with their distances from the Sun in binary code. Then there is an area describing the path of the probe out of our solar system. The alien may not know what the arrow represents, but it was worth a shot. We may never know if anyone comes across this probe, but if they do, let us hope they can decipher it!

For more of our attempts to communicate with aliens, see the Voyager vinyl records!

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Planet Earth in the Splash Zone

We often take for granted our Earthly paradise; with its warm temperatures and comforting blue skies, it’s easy to overlook the uniqueness that is Earth. This is even especially true when we consider the vast amount of liquid water on our planet. Water itself is not all that special, it can be found all over the solar system and presumably all over the universe. But what is special about Earth’s water is that it is in the liquid state and it is in such a vast quantity. But where did all this water come from? Was it always here or did it come here from elsewhere? The answer may surprise you.

Nearly every drop of water on Earth originated at the edge of our solar system. Here at the edge, in the Kuiper Belt and the Oort Cloud, is the realm of comets. When the solar system formed, comets were the byproducts of ice that didn’t accrete into much larger planets or dwarf planets; essentially they are ice balls floating in space. It is from these ice balls that we get all our water on Earth. When a comet slammed into Earth during the period of Late Heavy Bombardment nearly 4 billion years ago, its ice melted from the energy released in the impact, thus leaving behind liquid water.

The theory that comets brought all our water is evidenced by a neat calculation which involves counting lunar craters. When we look at certain valleys on the Moon where we know their age due to radiometric testing of Moon rocks returned from the Apollo astronauts, we can count the impact craters in these valleys. When we get a number, we then know how many impacts occurred in a specific, closed area, over an exact time scale. From there, we can extrapolate to the size of the Earth’s surface and to the age of Earth, and we can calculate the estimate of the number of impacts that occurred on Earth. From there, integrating over zero to infinity for the radius of a comet using a mass distribution equation for formation of comets, and we get the number of kilograms of ice that was brought to Earth via comets. The number we get is nearly exactly how much water there is on Earth, thus proving that comets brought Earth all her water.

For a more mathematical explanation, take a look at this picture, taken from a textbook that I used in a previous semester for an Astrophysics class. This was actually a homework problem that I had to solve; later after handing in the work, the professor gave us the book’s solution manual where this picture comes from. It would have been nice to have the solution while doing the problem! (but I got it right anyway!)

 

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A New Generation of US Spaceflight

A new era of spaceflight is underway in America. The Space Shuttle program was retired in 2011 and ever since, if NASA wants to send an astronaut so space, they must buy a ticket on the Russian Soyuz rocket. But this status quo of depending on another nation to carpool to space is about to change. NASA has been funding the designing, building, and testing of a new rocket and capsule system for bringing Americans to space. It is called the Orion Program, named after a mythical Greek figure, just like the Apollo, Gemini, and Mercury programs before it.

The Orion capsule, which sits upon the Space Launch System (SLS) rocket, draws more similarities to the Apollo capsule, rather than the Space Shuttle, since Orion is a multi-stage, one time use rocket, which re-enters Earth and deploys parachutes before a soft landing in the ocean, rather than the more airplane-like and reusable design of the Space Shuttle. Thus it is more appropriate to relate Orion to Apollo. The new capsule is designed to hold a crew of 4 astronauts, as compared to Apollo which held 3. 

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It also boasts a 5 meter diameter heat shield to protect the crew during re-entry, a full meter greater than Apollo. The larger size of the capsule is best judged by 5.9 cubic meter volume, which is more than 50% more space than Apollo. The cockpit has been updated from 60’s era technology of gauges, dials, flips and switches to touchscreen computers and state of the art display features (as well as powerful computers as opposed to the computers on Apollo which had less memory than modern day calculators!). Furthermore, the Service Module of Orion is larger and more spacious than Apollo’s, plus it houses two, 3 meter radius solar panels which extend off the sides in order to supply more power to the craft than ever before.

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Read more about Orion on NASA’s website, here! Or, here in this great article.

Just for comparative reference, here is a figure showing the Orion rocket side-by-side with the Apollo Saturn V on the left, the Space Shuttle second from the left, and the Aries 1 rocket third from left which is currently used to bring cargo up to the International Space Station:

orion vehicle comparison

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Eratosthenes Measures the Earth

How do you measure the circumference of the Earth? It’s not like you can take out a meter stick and lay it end to end hundreds of thousands of times. Today with satellite technology and GPS we can easily complete this task and get an extremely precise answer: 40,075.017 kilometers. But how might a Greek scientist living in 3rd century BC Egypt accomplish such an undertaking?

The answer is ingenious. It always amazes me how brightest of minds comes up with the most remarkably clever solutions to seemingly impossible questions. Who wakes up in the morning and declares, “I want to measure the circumference of the Earth?” or any other crazy question of that type? Talk about taking on the some of the greatest challenges head on.

But I digress, how did a man named Eratosthenes find an answer to a presumably unattainable question? He did so by harnessing the power of the Sun and his knowledge of basic geometry. Eratosthenes lived in the Egyptian city of Alexandria, but had a correspondent in Swenet (now modern day Aswan). Eratosthenes’ friend in Swenet told him about a well in town that one could see all the way down to the water on the day of the Summer Solstice at Noon. This may not sound all that exciting but what that really means is that there is no shadow on this special day of the year. Even the lack of a shadow may not seem all that earth-shattering, but the lack of a shadow means that the Sun is directly overhead, at the zenith.

Eratosthenes pocketed this information and then observed the Sun in his home of Alexandria on the Summer Solstice at Noon. What he found was that shadows were cast in Alexandria and thus the Sun was not directly overhead. So, being a curious man, Eratosthenes pulled out his trusty gnomon (an ancient tool for measuring angles), and measured the angle of sunlight at Alexandria. What he found was that the Sun was about 1/50th of a circle from the zenith at Noon on the solstice. This comes out to roughly 7.5 degrees. Next, using basic theorems of geometry, he equated the angle of sunlight to the angular distance between the two cities as measured from the center of the Earth. Now knowing the angle is only half the battle in determining a measurement for the Earth’s circumference. Eratosthenes needed a measurement of the metric distance between the two cities. The story says that, as any right-minded man would do, he hired an army to march from Swenet to Alexandria and keep count of the number of steps they took during their journey. The marching soldiers related their steps to the Egyptian unit called the stadia, which translates to 157.5 meters, and came up with 5000 stadia between the cities. When a little algebra is applied, this comes out to about 700 stadia per degree of Earth. Now multiplying by 360 degrees and changing units from stadia to meters, you get 39,690 kilometers as the circumference of the Earth, which is a 1.6% difference from our current accepted value! 1.6% off! There are modern day experimental labs which strive for anything less than 5% error, never mind less than 2%!

It astonishes me how the grandest questions often have the cleverest, yet simplest solutions. More often than not in astronomy, scientists must come up with clever, indirect methods of measurement, since the objects that astronomy deals with are too big and/or too far away to measure directly. But the thrill of exploration and the innate human desire to learn has driven the brightest minds of every generation to come up with new and ingenious ways to come up with answers to the biggest of questions, using nothing but wit and basic mathematical principles.

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Sir Isaac Newton’s World

Sir Isaac Newton was born Christmas day, December 25, 1642 in the small hamlet of Woolsthorpe in the county of Lincolnshire in the English countryside. He lived a full 84 years, in which he revolutionized our fundamental understanding of the universe by discovering his Law’s of Motion, Law of Gravity, and laws of Optics; as well as inventing the Newtonian telescope; and independently inventing Calculus. He has gone down into the history books as one of the smartest individuals to ever live, as well as one of the most influential scientists to ever live. He later died peacefully in his sleep on March 20, 1727. For more specific details on his life, check out this article by Dr. Robert Hatch at the University of Florida.

Newton’s lifetime overlapped with a very interesting part of history. Here are two events which occurred during his life:

February 1692 (Newton, age 50): The Salem Witch Trials took place in Salem, Massachusetts.

This famous event in the young colony of Massachusetts was a widespread public hysteria of the presence of witches in the small, rural town of Salem. Public fear over evil spirits and sin brought forth public trials of those who were accused of witchcraft. These trials were unfair and unjust, often leading to the death of the accused after a dubiously justified trial.

1689 (Newton, age 47): John Locke publishes his Two Treatises of Government.

        This essay later heavily influenced the American revolutionists in the British Colonies, and thus was a major source of inspiration towards the founding of a new and independent United States of America. In it, Locke outlines his idea of the “State of Nature” whereby all men are born into the world free of tyranny, but eventually we give up some of these freeborn instilled rights in order to join a society where we all mutually benefit. But he warned of society and those in charge of it becoming too powerful and tyrannical.

As well as fascinating historical events, Newton’s lifetime overlapped with many famous and influential people, including other scientists, political figures, artists, and many others. One example is Johann Sebastian Bach.  Bach was a famous composer of the Baroque Period, especially writing with the piano and violin. His major works include Mass in B Minor, The Well-Tempered Clavier, and his Lullaby. 

As I think about Newton and the world he inhabited, I think it’s very useful to sometimes step back, away from your subject of interest, to investigate the world in which the subject lived it. Often times we isolate our subject, choosing to focus in on him/her entirely, but we forget that any person is product of their environment. Therefore it is important to understand that environment. That is why I found learning about the world around Isaac Newton to be almost as important as learning about the man himself. For example, Newton of course was this trailblazing explorer in the day’s most cutting edge fields, but yet we look across the ocean to the America’s and we see that the people of Salem, Massachusetts still believe in and live in a fantasy land where superstition and rumor overwhelms facts and reality. Newton was an exceptional human being for not only his time, but even by our standards today.

 

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The Grandest Experiment

The majority of physics experiments take place in a small lab found in the basement of a university science building. However, for a grand hypothesis, one needs a grand experiment. The year was 1919 and a nervous Albert Einstein awaited the results of an experiment on the scale never before seen nor bested up to the present day. Four years earlier, Einstein published a paper outlining his Theory of General Relativity, the bold claims of this paper brought on skepticism at first, but soon he would win over the hearts and minds of every scientist and civilian alive. Einstein postulated that the immense mass of large bodies, such as the Sun, would bend the fabric of space-time and thus, light waves would be bent as they travelled near these gravity wells. Such a proposition goes against the days accepted theory put forth by Newton 200 years earlier: that all light travels in straight lines. So how could Einstein prove that light can be bent by gravity?

The answer would come courtesy of one of nature’s most awe inspiring events, a total solar eclipse. A solar eclipse occurs when the Moon passes directly in front of the Sun, and thus blocks the sunlight from reaching Earth. These eclipses can only occur when the Moon is new in its phase. Not because the Moon is biggest at that time, it is always the same size no matter the phase! But rather because that is the only phase in which the Moon can possibly be in line with the Earth and Sun. We have a new Moon 13 times per year but we don’t experience 13 solar eclipses a year due to the Moon’s 5 degree orbital tilt. The total blockage of the sun during a solar eclipse only lasts about 7.5 minutes, but for that time the sky darkens and the stars come out. Einstein’s theory postulated that the light from distant stars which were hidden behind the Sun would be bent around the Sun and therefore be observable. Normally, this theory would be impossible to test since the Sun’s light drowns out any observable stars. But the uniqueness of the eclipse allowed just enough time for Sir Arthur Eddington, who took on the challenge of capturing the picture on Einstein’s behalf,  to take a photograph of the sky, including stars. The idea was, if we know the exact celestial coordinates that the Sun blocks, we will know the exact stars that lay hidden behind the Sun. When the lights go out during the eclipse, if those stars are visible at the fringe of the eclipse, then we know their light has been bent, thus proving the theory.

Once the picture (see the original negative here!) was developed and scrutinized, it was determined that Einstein was correct. He became an overnight celebrity not only in the science community, but among everyday people too. His theory still stands as accepted in the physics community to this day and has been verified by the eclipse test many more times, and by other tests designed in years to come, but none used tools as grand as a total solar eclipse!

Want to learn more about the factors that go into how and when a solar eclipse can occur? Check out this awesome video!