Monday, November 28, 2016

Obscured by Golden Clouds: Venus vs Mars


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Venus was named after the Roman goddess of love and beauty because of its own beauty and brilliance. It is the second brightest object in the night sky after the Moon. It is bright enough, in fact, that on a clear, moonless night, it can cast shadows upon the surface of the Earth. It seems like a welcoming world to us Earthlings, as it is the closest to our planet and the most Earth-like in size and composition. It is almost the exact same size as the Earth in terms of mass and diameter, it is made of the same rocky material, and it even has an atmosphere with similar (albeit more extreme) properties as the one that we breathe.
All these truths, coupled with the golden clouds that hid its surface from our telescopes led many fanciful astronomers and science-fiction writers to believe that this world harbored life of its own. It was only logical that such a beautiful and inviting world would host equally beautiful and inviting creatures. But as the decades progressed, our technology got better and better and with it our understanding of the universe increased as well. This increase in understanding extended to our knowledge of our closest neighbor, and we now see it for it really is: a hellish world with a jagged, black, lifeless terrain. Those beautiful golden clouds that hid the surface from our view turned out to be clouds of pure carbon dioxide gas, the presence of which we fear in our own atmosphere. Those clouds trapped the heat of the Sun in a runaway greenhouse gas effect, which superheated the planet’s surface to a scorching 460℃ (860℉), hot enough to melt lead. The destructiveness of these clouds do not stop there. They are so dense and plentiful that they exert a pressure equal to the pressure exerted by the Earth’s ocean on a submarine 1 kilometer below its surface, pressure enough to crush a human skeleton.
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Mars, our second closest neighbor, was named after the Roman god of war because of its blood-and-fire-red hue as seen from the Earth’s surface. We equate that color with the blood of war, with pain and suffering, with heat and flames, with the devil and hell itself. This world is one that is far from welcoming, and science-fiction film producers quickly took to depicting its surface as one of intense heat and jagged peaks, as can be seen in films produced as recently as the 1960s, like Robinson Crusoe on Mars, in which our marooned protagonist must overcome the planet’s cruelly hostile terrain as he awaits the arrival of a rescue crew.
In time, just as it did with Venus, our understanding and perception of the red planet greatly transformed. Our landers and orbiters have found that not only is it not the world of hellfire that we once thought, it is actually quite cold. The surface can experiences lows of −153 °C (−243°F) at the poles, and highs of 20°C (68°F) at the equator. Its days are only 40 minutes longer than our own, so Martian settlers would experience very little in the way of cosmic jetlag. Scientists have even found there to be liquid water, the very stuff that sustains us and all life as we know it, flowing upon the surface of that red planet.
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From world leaders like President Barack Obama to great minds like Stephen Hawking to captains of industry like Elon Musk, Mars has come to be seen as a lifeline for the human race. Mars, not Venus, is the only planet that truly welcomes us. It is the only planet other than Earth upon which we can make a true and lasting home. Our nightmarish image of Mars that we held so tightly for hundreds of years was one that actually reflected the reality of Venus, whereas our heavenly, welcoming image of Venus turned out to be more fitting for Mars. We are flanked by these two worlds which serve as constant reminders to us of how little we truly know. They are constant reminders that, what may seem to be true based purely upon the most superficial and shallow observations, can turn out to be further from reality than we could ever imagine.

Saturday, October 8, 2016

The Electromagnetic Spectrum: More than Meets the Eye

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There is so much more to light than we can see with our eyes. In fact, the visible portion of the electromagnetic spectrum represents (much) less than 0.001% of the whole spectrum. We can see light with wavelengths between 400 - 700 nanometers (0.0004 - 0.0005 centimeters), but wavelengths can be as long the universe itself or as short as a planck length. There is, therefore, so much knowledge that is hidden from our eyes, but with modern technology, we have been able to pierce through that veil of ignorance in order to reveal many of the universe’s greatest secrets. Take, for example, the Zone of Avoidance from my last piece. By observing in the infrared, we were able to see beyond all the dust of the Milky Way that obscures so much of the night sky. We gained new knowledge of our galaxies trajectory through the cosmos, knowledge that had been completely hidden to us as a result of our eyes’ natural limitations.
So, in this piece I will present you with images of one of the famous astronomical objects of all time: the Crab Nebula. Each image will depict the nebula as it can be “seen” in different wavelengths. Next to each image will be an image of the telescope that did what the human eye could not. Under each image will be a list of other types astronomical objects that can be seen particularly well through each wavelength. And so, without further ado…

Radio Waves  


Telescope:

ALMA Radio Array in the Atacama Desert of Chile
Other objects:
  • Cosmic background radiation (evidence of the Big Bang that permeates the universe)
  • Quasars (galaxies with incredibly “bright” and active cores)
  • Blazars (compact quasars with supermassive black hole’s at their centers)
  • Pulsars (rapidly rotating neutron stars that spit out beams of radiation from their poles)
  • Masers (clouds, planetary atmospheres, and comets)

Infrared 

Telescope:
Chandra X-Ray Observatory
Other objects:

  • Objects obscured by cosmic dust
  • Star clusters

Optical


Telescope:

Hubble Space Telescope
Other objects:
  • Stars
  • Galaxies
  • Planets
  • Nebulae
And the list goes on and on, of course….

 Ultra Violet

Telescope:
Ultraviolet Imaging Telescope
Other objects:
  • Interstellar medium (gas and dust that exists in the space between stars)
  • Young stars
  • Galaxies (in particular with regard to galactic evolution)
  • Any hotter kind of object, so an object at the beginning or end of its life cycle would grow particularly bright in ultraviolet

 X-Ray 

Telescope:
Chandra X-Ray Observatory
Other objects:
  • Extremely hot objects
  • Black hole emissions (the black hole itself cannot be seen at any wavelength because no light can escape its gravitational pull, but material falling into a black hole can emit X-Rays)
  • Neutron stars

[Check out the Citations/Sources page for all the attributions for the videos/information used in this article. If you want to learn more about this topic, feel free to click around on those links. Thanks for reading!]

Cosmic Dust, the Zone of Avoidance, and the Great Attractor

Cosmic Dust: the Zone of Avoidance
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When we think of space, we typically think of the absolute largest things in the universe. We think of objects that are as massive as billions of Suns or that span distances in excess of a million light years. These objects are so fascinating and different than anything we have here on Earth that it can be very easy to overlook that collection of unassuming, minuscule particles known as cosmic dust.  Cosmic dust is everywhere. Between planets within the Solar System, between the stars of the Milky Way, and between the galaxies themselves. Much like dust here on Earth, the stuff just gets everywhere. And, once more, like the dust here on Earth, it can be quite annoying for people to deal with....


The Zone of Avoidance
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You may find it hard to believe that, despite our vast knowledge of the cosmos, there remains a large swath of the universe right at our doorstep that we know little about. This region of space, located at the galactic disk of the Milky Way is called the Zone of Avoidance (ZoA), and it is constantly obscured by the interstellar dust of the Milky Way. Approximately 10-15% (more on the later) of all non-dark matter in the Milky Way is dust, so it’s not surprising ZoA obscures a whopping ≈20% of extragalactic space. This leaves a significant gap in many galaxy catalogues because it is nigh on impossible to catalogue that which we can’t even see. The most notable object that remains a mystery to us because of its location within the Zone of Avoidance is a mysterious and powerful object known only as the Great Attractor.


Great Attractor
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Although the universe is expanding, the Milky Way and her galactic neighbors are not growing further and further apart from each other as one might expect. In reality, they are all being drawn toward a single point in space known only as the Great Attractor. For years we had no way of being certain as to the nature of an object that could exert such a powerful gravitational pull on our galaxy. Luckily, however, x-ray and infrared waves are much better at passing through the dust of the ZoA and we were able to determine, with the help of x-ray and infrared telescopes, that a galaxy supercluster more massive than 1,000,000,000,000,000 (1,000 trillion) suns existed right near the center of the Great Attractor. This supercluster is now known as the Norma Supercluster, and it is responsible for the motion of all of the galaxies in our neighborhood.
But the mystery didn’t end there. Astronomers soon realized that the Norma Supercluster itself was being pulled by another, even more massive object -- and she was, of course, taking the Milky Way along for the ride. That other, more massive object turned out to be another supercluster known as the Shapley Supercluster, and it is made up of more than 8,000 galaxies with a total mass of over 10,000,000,000,000,000,000 Suns (10,000 trillion).
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Depending on what you consider to be a single object, the Shapley Supercluster is the most massive object within a billion light years. Now, as it is a supercluster, it is quite reasonable to argue that the cluster isn’t an object at all, merely a collection of objects. But then if you decide to go down that route then you can no longer refer to even a galaxy as an object because, after all, what is a galaxy other than a collection of stars? And then, (stepping tentatively out of my domain and entering one of philosophy and biology) what is a person other than a collection of cells? But, of course, I digress.
Anyways, in the words of Fraser Caine, “as we hurtle through the cosmos, gravity shapes the path we travel”. We are pulled toward the “Great” Attractor, which is in turn pulled toward the even greater Shapley Supercluster, which is then pulled in some other direction by some other object or cluster. And all of these discoveries were set off by our ability to finally peer through the Zone of Avoidance, but the dust of the Milky Way does far more than just act as a frustrator for extragalactic astronomers…
The Galactic Core
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...it also acts as a frustrator for intragalactic astronomers.
Our galaxy is a whopping 100,000 lightyears in diameter, and yet we can only see a measly 6,000 lightyears into the disk at optical wavelengths. This is caused by the thick band of dust cosmic dust that surrounds and permeates the galactic disk and reflects light at optical wavelengths (but not infrared). The dust is so problematic that it leaves our knowledge of the galactic center severely lacking. For example, you may consider it to be a commonly known fact that our galaxy revolves around a supermassive black hole at its core that we call Sagittarius A*. That is, however, not a fact. There is strong evidence that the black hole exists, but that is all that it is: non-conclusive evidence. Although it is admittedly pretty darned near conclusive. Don’t let this article mislead you, there is almost certainly  a supermassive black hole at the center of our galaxy and most every other galaxy.
Zodiacal Lights
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Working our way ever inwards, cosmic dust is also present in our Solar System, which makes for a fascinating effect when observed from Earth. The dust of the Solar System exists in a form referred to as the Interplanetary Dust Cloud, which is made up of a very small amount of dust spread out over an incredibly large area. Individual dust grains near Earth’s orbit are typically between 10-100 micrometers in size (0.001 to 0.01 centimeters). There is such little dust that if you were to take all the dust in the interplanetary dust cloud and condense it into one shape, you would only be able to produce an asteroid with a diameter of approximately 15 km and a mass of 2.5 g/cm3. And yet, despite its apparent scarcity, it does some amazing things.
An important but oft overlooked fact about the dust of the Solar System is that the individual grains have, at least on a cosmic scale, very short lifespans. This means that none of the dust we have in the Solar System today is leftover from the system’s earliest days as a protoplanetary disk, despite what common sense might suggest. So where does all that dust go? Well, it has a few options. It can either be cast out into the interstellar medium by radiation/solar wind from the Sun, or radiation from the sun can actually slow the grains down as they try to complete an orbit, thus causing them to fall into the Sun itself. The dust can also collide with itself to form larger objects, at which point it is no longer dust, or it can be eaten up by the gravitational pull of the planets and comets.
You might be wondering how dust grains can still be present in the Solar System even though they have such short lifespans. New dust is formed by the collision of asteroids and comets, who then break up into smaller and smaller pieces until they become dust. Some dust even enters our Solar System from interstellar space. And just as our Solar System casts dust out into that region between the stars, other systems cast out dust of their own. In this way, some of the dust grains of our Solar System may be visitors from a distant, alien Sun. (Note, however, that dust in the Solar System that is of interstellar origin represents less than 0.1% of the total dust population).
On particularly dark nights, a faint glow can be seen stretching in a band across the sky. That band of light is called the Zodiacal Lights, and it is the light of the Sun being reflected by the many, scattered, minuscule grains of dust in the inner Solar System. And that’s only one way that by which cosmic dust has been known to light up the sky...

Here on Earth: Shooting Stars, Noctilucent Clouds, and Phytoplankton
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Between 5 and 300 tons of this stuff enters the Earth’s atmosphere daily. Grains come tearing through the air at breakneck speeds -- up to 248,000 kilometers per hour. All of that air resistance causes the grains to pick up some incredible levels of heat exceeding 1,600℃ (3,000 ℉), so the ones that are large enough (greater than 2 millimeters in diameter) streak across the night sky in the form of shooting stars. Shooting “stars” are not stars at all, they are simple grains of dust like you might find on a beach of under your couch.


But not all dust burns up in a blaze of glory. Some of it enters the uppermost regions of Earth atmosphere and serves as a platform upon which water molecules can condense and ice crystals can form. These grains of dust become the foundation of noctilucent clouds, the kind of cloud that floats above the Earth and above all other clouds. The dust that forms these clouds eventually makes its way all the way down to the Earth’s surface. It seeds the ocean with iron, which serves as an important part of the food chain. It feeds phytoplankton, which is the basis of the entire food chain. It’s extraordinary. Those little ocean dwellers eat stardust, and that stardust eventually works its way all the way up the chain into the diets of humans. The same stuff that hid the so-called “great attractor” from us for decades is the stuff that keeps us alive on a daily basis.
[Check out the Citations/Sources page for all the attributions for the videos/information used in this article. If you want to learn more about this topic, feel free to click around on those links. Thanks for reading!]

Wednesday, July 13, 2016

Kepler’s Third Law of Planetary Motion

  1. The orbit of every planet in the Solar System is an ellipse with the Sun at one of two foci.
  2. A line joining a planet and the Sun sweeps out equal areas during equal intervals of time.
  3. The square of the orbital period is directly proportional to the cube of the semi-major axis of its orbit.
The square of the orbital period is directly proportional to the cube of the semi-major axis of its orbit.
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The major axis of an ellipse is the shape’s longest diameter, and the semi-major axis is half of that distance (the longest radius). In an orbit, the semi-major axis is the distance from the center of the ellipse to the point of perihelion/aphelion. Kepler’s Third law (in its simplest form) holds that the mathematical relationship of a planet’s orbital period to its semi major axis is such that T2 = a3, where T = orbital period (in Earth years) and a = the length of the semi-major axis (in Astronomical Units).  
Using this formula, we can find that length of the semi major axis of a celestial body given only its period or vice versa. This is especially useful when it comes to the study of exoplanets. Most exoplanets are discovered using something called the Transit Method, which measures the dip in brightness of a star as a planet passes in front of it from the perspective of Earth. Using this method, if everything goes perfectly and we are able to measure multiple consecutive transits, we are able to determine the orbital period (T) of the planet, from which we can use Kepler’s Third Law to determine the length of its semi-major axis (a).
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Let’s say, for example, that we are astronomers on the planet that is known to Earthlings as Trappist-1b, and we are observing a nearby star in search of exoplanets. Eventually, we notice a slight dip in the star’s luminosity, and twelve Earth-years later, we notice the very same dip appear once more. Given this information and using the formula T2 = a3, we are able to determine that the length of the semi-major axis of this planet’s orbit is a = 3√(122) = 5.2 AU, so if the planet’s orbit has a negligible level of eccentricity, then we now know it is located approximately 5.2 AU away from its parent star.
That star we observed just so happened to be the Sun and the planet whose transit we measured was none other than the great Jupiter. Jupiter does, indeed, have a negligible level of eccentricity (0.048), so our calculation does come out to be correct. It is important to note, however, that the simple T2 = a3 formula only works when the mass of one object is immensely dominant over the other (the Sun holds 99.8% of the entire Solar Systems mass). A more rigorous form of the law
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takes into account the masses of the two objects (M1 and M2, in Solar Masses) and the gravitational constant (G, 6.67408 × 10-11 m3 kg-1 s-2), and can be used in systems like binary star systems and planet-moon systems, in which there is no overly dominant mass.
[This is part three of a ten-part series called The Laws That Govern The Universe. Stay tuned for more! Check out the Citations/Sources page for all the attributions for the videos/information used in this article. If you want to learn more about this topic, feel free to click around on those links. Thanks for reading!]

Thursday, June 23, 2016

Penny4NASA


Take Action Here: http://www.penny4nasa.org/take-action/



“Mars has been flown by, orbited, smacked into, radar examined, and rocketed onto, as well as bounced upon, rolled over, shoveled, drilled into, baked and even blasted. Still to come: Mars being stepped on.”
-Buzz Aldrin

Thursday, June 16, 2016

FEATURED: The Politics of Space Exploration (by PolitiTurk)



        Throughout the course of history, there has always been an uncharted frontier for Americans to explore–whether the New World, the West, or the depths of the oceans. Now, thanks to the effects of industrialization, the frontiers of this world are beginning to dwindle. There will, though, always be one unexplored frontier–one which cannot possibly be explored in entirety, never ceases to drive our curiosity as a nation, and inspires people around the world to dream big–space.
        Ever since the Space Race of the 1960s, the United States has been at the forefront of space exploration. While other nations have accomplished similar feats as those of the United States, no nation's space agency is as well-known as NASA, the National Aeronautics and Space Administration. Since Armstrong first walked on the moon, NASA has inspired young minds to dream big, and even become astronauts. This ability to accomplish such great technological feats has been, for decades, a result of major bipartisan support for space exploration. For years, it has been an issue upon which Democrats and Republicans alike can, for the most part, unite and agree.
        Space exploration drives us forward as a nation, unites us under the cause of curiosity, and pushes us "where no man has gone before." Not only is there an ever-present desire in the American public for space exploration, but politicians, as well, seek to continue to explore our own solar system and beyond. Many view it as essential to the national agenda, as well as to our nation's scientific advancements. No matter how imperative the future of space exploration to this great nation, though, it is often undermined by a Congress unable to either agree or compromise.


        Recently, NASA requested its 2017 budget from various branches of the U.S. Government–the House of Representatives, the Senate, and President Obama. The budget was received rather differently from each respondent. Both the Senate and the President did not give NASA significant advances in funding; both of their budget proposals placed far more emphasis on space travel than on earth science, as well. The House committee that decides upon NASA's annual budget, however, was rather generous in its allotting of funds. Seeing that NASA needs a certain amount of funding for its ambitious space travel programs, the House provided NASA with a hefty $19.5 billion budget for 2017. This was $200 million more than the Senate's proposal and $500 million more than that of the President.

        This budget, which will have to pass through both the House and the Senate in order to become effective, could potentially grant NASA the ability to expand its programs and bring seemingly distant exploratory missions to the near future. However, the House and the Senate have not agreed upon a budget for the NASA since 2010–the Senate often being reluctant to endorse space spending in all fields. NASA's budget has historically been lowballed, which has resulted in NASA being limited in its capabilities. Should Congress be able to agree upon a substantial budget for NASA this year, the United States will be able to maintain its position of global leadership atop the ladder of space exploration. As stated in a Huffington Post article by Eileen Collins and Nick Lampson, "As a nation, we must put politics aside to ensure that expanding the space frontier occupies a prominent place on our national agenda."


        In the past several years, some have criticized the government's waning support for space exploration, as it has given rise to the growth of privatized space corporations, such as Elon Musk's SpaceX and Jeff Bezos' Blue Origin. SpaceX, in particular, has publicized its intentions to launch missions to Mars in the next several years and has given a new hope to those wishing to see more space missions in the near future. The sort of fascinating research tests and propositions made by SpaceX have demonstrated that space exploration is not a lost cause. SpaceX, as well, has proven that, if NASA were to receive more substantial funding from the government, it would be able to accomplish more notable feats–as opposed to those it has focused on recently, the majority of which do not excite the public as much as the thought of a mission to Mars. 

        In addition, the House has demonstrated a great deal of interest in the rise of America's commercial space sector. In May, it passed the SPACE Act, which is helping to promote growth for companies like SpaceX, which possess similar objectives to NASA, yet far more capabilities. In recent news, SpaceX failed to successfully land its Falcon 9 rocket on a cargo ship, only to successfully land it on the ship during a second test. For companies like SpaceX, which have far more budgetary flexibility than NASA, it is okay to fail once in a while. Nonetheless, NASA has shown interest in cooperating with SpaceX's proposed missions to Mars in the future, giving hope to a potential merge of public and private spaceflight organizations.
        Moreover, although space exploration seems to be an issue with a great deal of bipartisan support, there is, nonetheless, a certain level of partisan division regarding the placement of funds for NASA. While Republican politicians tend to favor more funding for deep-space-exploration missions, such as NASA's planned Orion Exploration Mission, Democrats typically support more tangible space projects–such as those regarding NASA's earth science division, which often deals with research on climate change and has, for years, received inadequate government funding thanks to an incompetent Congress.
        As Lamar Smith, Republican Representative and chairman of the House Science, Space, and Technology Committee, told The Atlantic in an interview, "The future is bright for discovery, but failure to invest in innovation and space exploration could leave America in the dark." It is clear that members of both major parties see the need to invest in the future of space exploration, yet it is often the result of partisan quarreling that NASA's budget remains too low for it to strive for anything truly revolutionary. If Congress can simply agree upon a substantial budget for NASA, it will allow the United States to remain a global leader in space exploration and to continue to push further into the infinite universe. 


[This article was provided by Michael Turk of polititurk.blogspot.com

Kepler's Second Law of Planetary Motion

  1. The orbit of every planet in the Solar System is an ellipse with the Sun at one of two foci.
  2. A line joining a planet and the Sun sweeps out equal areas during equal intervals of time.
  3. The square of the orbital period is directly proportional to the cube of the semi-major axis of its orbit.
A line joining a planet and the Sun sweeps out equal areas during equal intervals of time
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Kepler’s second law has everything to do with orbital speed. The speed of an object as it orbits a system’s center of gravity is not constant, but rather it varies depending upon where in its orbit the object is located. In an ideal orbit (a perfectly circular orbit), orbital speed will be constant or nearly constant, whereas in a more realistic, more elliptical orbit, the speed will vary greatly. These variations in speed are such that if a line were to be drawn between a planet and the Sun, the areas that would be swept out by the line as the planet moved along its orbit for a period of time will always be equal to one another, no matter where in its orbit the object is located.
Take, for example, Halley’s Comet, an object whose orbit (0.97 eccentricity) is just about as far from circular as one can get. The year is 1983, and Halley’s Comet is 3 years from reaching perihelion.
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After 6 years, the Comet will be just as far from perihelion as it is today, only going in the opposite direction. So, for this example, the chosen time interval is six years. During these six years, from 1983 to 1989, Halley’s Comet whips around the Sun with an approximate average orbital velocity of 55 kilometers per second (compare that to Earth’s measly orbital velocity 30 kilometers per second). From 1983 to 1989, an imaginary line joining the center of the comet to the center of the Sun sweeps out an area of X AU2.
Copy of Halley's Comet (1).png
Let’s fast forward thirty-one years to the year 2020. Now, Halley’s Comet is 3 years from reaching aphelion, and in six years the Comet will be just as far from aphelion as it is today, only going in the opposite direction. Where Halley’s Comet tore through the cosmos as it approached perihelion, Halley’s Comet will crawl through space at a speed of less than one kilometer per second (0.88 km/s, to be exact) as it approach aphelion (compare that to Earth’s 30 km/s and Halley’s perihelion speed of 55 km/s).
Copy of Halley's Comet (2).png
So, the rapid orbital speed of the comet as it approaches perihelion makes for a very short but wide triangle, whereas the slow movement of the comet as it approaches aphelion makes for a very long but narrow triangle. This effect is such that the areas of these two triangles are equal (X AU2 = X AU2). This will be true for any six-year (or whatever time interval you chose) period. The area will always be the same, no matter where you choose (whether or not the body cross perihelion and/or aphelion is not important) to begin your measurement of the area swept out by the line joining the two celestial bodies.
[This is part two of a ten-part series called The Laws That Govern The Universe. Stay tuned for more! Check out the Citations/Sources page for all the attributions for the videos/information used in this article. If you want to learn more about this topic, feel free to click around on those links. Thanks for reading!]