While astrology is widely disproven as a form of science in our modern age, it has its origins in the beginnings of computational astronomy. As explained by David Lindberg in his book The Beginnings of Western Science,
“By the end of the fifth century B.C., Babylonian celestial divination had expanded to embrace horoscopic astrology, which used planetary positions at the moment of birth (or near the date of birth for such exceptional phenomena as lunar eclipses) to predict individual fortunes.”
By the time the Greeks inherit the Babylonians’ methodology, astrology and astronomy are inseparable.
The specific idea of the 12 zodiacs signs (although a 13th one actually exists as well) comes from the positions not of the planets, but of the Sun. As Earth orbits on the ecliptic, the Sun is positioned “within” a specific zodiac constellation during a specific time in the orbit. For example, between July 23 and August 22, the Sun appears to be within the constellation Leo. This is why my horoscope sign would be Leo, since I was born on August 7th.
However, because of precession, these horoscope signs are actually a lie. These signs are based on the positions of the Sun in relation to these constellations from almost 2000 years ago, when astrology began. Earth’s axis has since moved about 1/13th of the way through its precession cycle in that time, so horoscopes are off by about a month from the actual position of the Sun today.
So instead of being a Leo, I guess I have to start embracing my inner Virgo!
While there is not concrete, photographic evidence that Andromeda and the Milky Way are galactic twins, astronomers have found evidence that points them to believe so. This picture shows the twin galaxies surrounded by tens of dwarf galaxies in their local group. This image was uploaded from http://askanastronomer.org/galaxies/faq/2016/08/22/andromeda-milkyway-collision/.
Astronomers have declared that our galaxy, the Milky Way is one of the largest two galaxies in our Local Group, rivaled only by its own twin, Andromeda. However, while technology has advanced greatly within the realm of astronomy, we have not yet reached the point of searching beyond the halo of the Milky Way and observing our own galaxy as outsiders. Considering this then begs the questions: How do we know that we are one of the largest galaxies in our Local Group? What evidence points us to the theory that we are Andromeda’s twin?
Let’s first discuss the evidence that tells us that the Milky Way is one of the largest in our local group (so large that other galaxies actually orbit around us!). In the 1920s, it was first believed that the Universe was 300,000 light years across. This was revised shortly after to only 30,000 light years across. However today, astronomers are fairly confident that the Milky Way spans 100,000 to 150,000 light years in diameter. This was discovered by the complex tools of distance measurements that astronomers call “the cosmic distance ladder.” One of the first steps in this ladder is radio waves which are shot out to distances even beyond our solar system so that astronomers can measure the time is takes for the radio waves to come back. The next step in the ladder to uncovering the large size of our galaxy is parallax, which allows scientist to gather distances of close stars within the galaxy. Following this, astronomers use main sequence fitting ( a technique that compares the brightness and color of a far away star to that of a near star) to find the distance to stars that are of even greater lengths from us. Using these techniques, astronomers are able to measure to the ends of the galaxy and get a pretty good idea of how grand our galaxy truly is in comparison to others (Baraniuk).
Yet, this still does not answer how astronomers came to believe that the Milky Way and Andromeda are twins. Previous theories presented Andromeda as three times the size of the Milky Way. Nevertheless, this changed Australian astronomers published an academic article denouncing the previous theory and replacing it with the idea that Andromeda is less than or equal to the size of the Milky Way. Using a measurement technique that measured a the necessary escape velocity of a star leaving the galaxy’s gravity, these astronomers discovered the true size of our neighbor (Parks).
Furthermore, scientist came to discover that the Milky Way is also a spiral galaxy through many clues, the first being the disk of stars that we see in our night sky. This disk of compressed stars can be seen with the naked eye at night and leads scientist to believe that this image is really a look into the disk of our galaxy. Another clue as to the shape of our galaxy is the movement of our stars. Through locating stars’ locations by their rotational velocities, scientist discovered that these stars are located in concentrated spiraling branches, or the “arms” of our galaxy (Peshin). These clues (plus the “duck test” which you can read more on at https://www.scienceabc.com/eyeopeners/how-do-we-know-the-milky-way-is-a-spiral-galaxy.html) give way to the theory that, just like Andromeda, our Milky Way is a large spiral galaxy.
The Voyager 2 is a space probe that was launched by NASA in 1977 in order to study the outer planets. It is still traveling and is now sending back information about the outer solar system and is around 13 billion miles away from earth. There is a record inside the voyager made to display life and the diversity of life on earth. The record comes with directions for playing the record as well as earth’s location. The record can be found here; the beginning of the record is of people of different cultures speaking, and after a few minutes the record gets even weirder. Give it a listen!
This photo shows the scale of the Earth compared to other planets and the sun. While daunting, to see how small the sun is compared to other cosmic bodies, check out this article and video here!
Many people have talked about the feeling of walking outside, looking up at the night sky, and feeling small. You look out into the cosmos, see seemingly countless stars, and think that everything you do on earth is just immeasurably small. Despite many people feeling that way, few truly understand the real scope of the universe. Take our own solar system. Personally, as you may know, I’m a big fan of Pluto. Yet Pluto, when compared to the earth, is tiny, not coming close to taking up even half of our size. But it doesn’t stop there. As shown in the picture above, the Earth is barely a spec in comparison to the sun. That might make someone think the sun is a relatively large object in space, and might be fairly important. While that thought process feels right, in reality it is rather laughable. As demonstrated in the video, the sun is barely even measurable compared to other stars, and those other stars are next to nothing when compared to the Milky Way. The Milky Way is about a hundred thousand light years across, a number which seems unfathomable, that there could be anything so large that it takes light hundreds of thousands of years to travel. Yet the Milky Way, when compared to the rest of the universe is also merely a spec. The size and scope of how big things really are is simply beyond comprehension, especially when you have people who think the walk between Commons and Main Campus is far. The universe is bigger than people often think, and it’s important to put that into perspective.
One of my favorite pastimes is observing the sky at night and seeing which constellations I can point out. While I am no expert by any stretch of the imagination, I like to think that I have a basic knowledge of several “main” constellations — Orion’s Belt, the North Star, the Big / Little Dipper, etc. Knowing these constellations makes me feel connected to the universe in a very real way, as if those stars are not so distant after all.
My knowledge of the stars and passion for learning new constellations began during my time in high school at Montgomery Bell Academy, located here in Nashville. One of the excellent opportunities that my high school afforded me was the opportunity to travel to the school’s observatory on Long Mountain in Tennessee. This location has one of the lowest amounts of ambient light in the South, making it a perfect location for stargazing. I have many fond memories of trips to Long Mountain to look at the sky, gathered around a campfire with friends and marveling at the vastness of our universe. Nonetheless, the knowledge that we can gain from learning about the universe — in my experience — connects us with it, making the universe seem just a little smaller and closer to home.
We all know that light travels fast – 299,792,458 meters per second, to be precise. Still, if the sun were to suddenly disappear into a mysterious void, you and I on Earth would not notice for about 8 minutes and 20 seconds. Or would we? Would we not immediately feel the sudden jolt of our gravitational big brother vanishing, sending us hurtling directionless through space?
Interestingly, we would not set off our usual orbit until the light from the sun goes out as well. As explained in this video, the speed of light should actually be called the speed of causality. Things in the universe cannot interact with each other faster than light can travel, and thus gravitation waves such as those created by colliding black holes will not reach us faster than light travelling from a star that is the same distance away.
One of the coolest videos I have ever seen is the Powers of Ten video. In 1977 Charles and Ray Eames—the inventors of the Eames Office, a famous furniture company—in collaboration with IBM, created a video beginning in Chicago and gradually zooming out, transporting the viewer to the outer edges of the universe. Every ten seconds the video zooms out by a new power of ten. There are two main takeaways I got from this video. One is that the Earth, and myself, are extremely small. Practically nothing in comparison to the rest of the universe. The second is that as we zoom out there is a pattern rotating between a relative density of stuff to vast expanses of nothing.
This video reminded me of a video I first saw just over a year ago, which represents the The Digital Universe, developed by the American Museum of Natural History’s Hayden Planetarium. It uses “data from dozens of organizations worldwide to create the most complete and accurate 3-D atlas of the Universe from the local solar neighborhood out to the edge of the observable Universe.” This video begins on Earth and continually zooms out until reaching the edge of the observable universe, 13.7 billion light-years away, before zooming back into Earth. This video had a profound effect on me. Like the Powers of Ten film, it emphasizes just how tiny and insignificant Earth is. However, as the video zooms back in, hurtling towards Earth, the placement of our beautiful planet seems perfect. All of the things that have led to life on this one speck are anything but insignificant. It helps that it is accompanied by the musical masterpiece “Time” by Hans Zimmer. The Digital Universe tool can be found on the AMNH website and is free to explore.
Something that fascinates me is the idea of scale of our universe. In particular, “scale” relative to a more traditional size/distance scale that we use more often. The metric scale, whose utility to humans generally ranges from millimeters to kilometers (measurements that we are easily able to estimate and compare), represents an indescribably minuscule spectrum of distance measurements when compared to the gargantuan size of our universe. See this slide show depicting the scale of our universe.
The universe is made of superclusters, which house local groups, one of which containing the Milky Way galaxy, which contains our solar system–inside that solar system lies our planet, Earth. Even the small minutiae of the universe (planets like Earth) are smaller in comparison to the Universe than the cells are that make up a human body. The diameter of the Earth is a breathtaking 12,742km–a number still much greater than most are able to comprehend–but the Earth itself contributes negligible mass to the universe as a whole. This subject is particularly intriguing to me because it challenges me to think in terms of distances/sizes that are much larger than we can comprehend.
Size of universe graphic. Obtained from SlidePlayer.com.
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The universe is much, much, much bigger than you may think it is. I personally find it inconceivable – my finite brain does not register infinity. The observable universe, as we know it today, is 14 billion years old – this means that we can see 14 billion light-years into the universe. Within this universe are billions of galaxies, each containing billions of stars. The Earth, and our Solar System, is nothing but a microscopic dot within the universe. Here are some mind-blowing facts about the universe that may help you put its vastness into perspective.
There are more stars in the universe than the number of individuals grains of sand on all the beaches on Earth combined.
The universe began at a single point in time and space (the Big Bang), but has been expanding since the beginning of time.
Its diameter spans across 150 billion light years.
As I contemplated about the universe, a couple thoughts came to my mind. Maybe the readers of this post can ponder them too.
How did the big bang happen? How did we go from nothing to something? How did we go from absolutely zero to infinity?
Are we just mere coincidence? Are we just products of atom collision and random chance? Or is there more meaning to life?
What is the likelihood of us being here at this moment? It seems like every collision had gone just the right way for us to exist? Is there a Creator behind the universe? Is there a design to it?
We may never know the answers to these questions for certain, but they’re worth thinking about for sure.
I’m sure you have heard the phrase “once in a blue moon” which is widely used to describe rare or seldom events. However, it wasn’t until I was in high school that I learned the true origins of the colloquial phrase. After seeing an article headline announcing the occurrence of a blue moon, my friend and I decided to drive out to a lookout late at night to get a better view. When we arrived, we were stumped to notice that the moon did not appear blue at all! At this point I looked for the article on my phone and actually read past the headline to hopefully provide an answer to our confusion.
As it turns out, a blue moon should not look any different from any another full moon! The term is just used to denote the second full moon of the month. I learned from the article that most months only exhibit one full moon due to the lunar cycle. According to NASA, the lunar cycle is 29 days and the average month is 30 or 31 days meaning that the blue moon should occur every 2 and a half years.
At the end of the night, we felt pretty silly. However, we were still able to see a beautiful full moon on a lovely night.
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