I’m truly baffled by the sheer size and scale of the Universe in comparison to the scale of the life I live, and the implications of that scale on finding life off of Earth. At any point in time, my attention is engulfed by only 10 or so meters of my surroundings, and often only a square meter in front of me when I’m sitting at my computer. We know much about the prospects of other life within our solar system, but as seen in the Powers of Ten video, there are several cosmic systems that absolutely dwarf our tiny planet and solar system. It is hard to believe that in the several cosmic systems shown as the video expanded from our 10^13 meter wide solar system to the 10^24 meter wide view of space (an expansion of almost a trillion times), there is not a single planet or habitat with ample conditions to house life. The search of each additional power of 10 surrounding us might take 10,000% as much time as the last, but the seemingly infinite expanse that we have to search makes me terrified, hopeful, and excited.
The topic associated with astronomy that intrigues me the most, at least with regards to the list provided, is definitely the vastness of the Universe. As a nerdy fan of late night, I can’t help but find Neil deGrasse Tyson’s appearances extremely entertaining. While I find that his talks often lack substance or depth, his enthusiasm for science is infectious. In the video below, he mentions dark energy and the expansion of the universe, and the acceleration of said expansion.
Tyson then expounded upon his previous conversation point, saying that over time, this unknown pressure that is accelerating the universe’s expansion will eventually expand to the point where other galaxies would be lost to us. However, could our technology not improve over that time frame to the point where there would be no difference in what we could observe?
He also brings up the point that if in the future, galaxies we know of now will no longer be observable, that means that there might be something in our Universe’s history that we no longer see. Essentially, that we’re staring at an incomplete picture while trying to explore the unknown. It sort of reminds me of the black box approach in science (see this link for more information). We try to operate and control all variables without necessarily understanding what actually happens. How can we study the future if we have an incomplete understanding of the past?
How fast is light? Nothing on earth is known to move faster, and in my opinion, we are actually very fortunate to be able to measure it. Aside the fact that light enables us to see, I am appreciative of it even more because if it were to get any faster by any stretch, astronomers would have to build new technology to measure its speed. This speed of light is known as the cosmic speed limit and even at the age of twenty-two, I am yet to experience anything more rightfully named. Why is It so hard for us to travel at the speed of light? The reason is that as you propel an object faster and faster, its relative mass compared to when the object is at rest, increases. This means that not only do we increase the speed object; we end up increasing the object’s mass as well, eventually resulting in an infinite mass which requires an infinite amount of energy to move it.
The moon is one of the most recognizable objects that appears in our sky and it has existed and has been celebrated for thousands upon thousands of years. Revolving around the Earth, the moon shows its face every night but with each cycle, appearing a little different. This is due to the moon phases- the variety of apparent shapes that it takes on based on our perspective of how sunlight reflects off of its surface from Earth. When the moon is in between the Earth and the Sun, light from the sun is not visible on the surface of the moon. When the moon is in the opposite position so that the earth is in between the moon and the sun, the moon is fully visible to us on Earth as all of the light that is reflected from the sun is visible. This is a full moon because, as the name suggests, the moon appears to be full. In between these two points, the moon can either appear to be a crescent shape, where less than half of the moon is visible, or what is known as a gibbous moon, in which more than half of the moon is visible.
Two types of eclipses may also occur due to the moon’s location in our sky, a lunar eclipse and a solar eclipse. A lunar eclipse occurs when the Earth is caught in between the suns light and the surface of the moon. This makes it so that the moon does not receive all of the suns light as it appears in the Earth’s shadow, giving it a reddish hue also known as a blood moon. A solar eclipse occurs when the moon is directly in between the sun and earth, causing the moons shadow to be cast down on earth. This form of eclipse is significantly rarer than its counterpart as the moon is much smaller than earth, resulting in a much smaller shadow.
The actual size of the universe is basically immeasurable as it is constantly expanding. But even if we could measure it, our human brains wouldn’t actually be able to understand howbig it really is. Our solar system is roughly 122 AU, an AU being the distance between the Earth and the sun. This is 11,000,000,000 miles. Still, even the solar system is too big to grasp.
The average distance from the Earth to the Moon is about 238,900 miles. This seems better to work with, but as you see from the picture above, you can fit all of the planets in the solar system into this distance. The chart below states each of the planets average diameters.
Measurements from Google.
Planet
Diameter (mi.)
Mercury
3,032
Venus
7,520.8
Mars
4,212
Jupiter
86,881.4
Saturn
72,367.4
Neptune
30,599
Uranus
31,518
Even the closest thing in the universe to us is an unbelievable distance away. If you add up all of these diameters you get 236,130.6 miles, so even with all the planets there, you still have room for Pluto!
Major Planets and Planetoids in the Solar System, to scale. Illustration by Roberto Ziche. Source: user kitsua on reddit
Have you ever wondered just how big the Solar System is? One helpful website to answer that question is Josh Worth’s “If the Moon Were Only 1 Pixel” site. This beautiful website allows you to scroll through the Solar System, to-scale, as if the Moon were only 1 pixel (that is, teeny-tiny and barely visible on your screen). You can scroll at your own pace, travel at the speed of light, or hop straight to different objects in our Solar System. Check it out! I bet you’ll be surprised at how overwhelmingly empty the Solar System is. Scrolling for minutes through the vast nothingness that separates the planets really hammers home how alone Earth is, and it may make you realize how colossal a challenge it will be to send people to Mars. What have you noticed that surprised you? Let me know in the comments!
You might find yourself looking at a (to-scale) diagram of the planets of the solar system (and Pluto), such as the following:
A solar system model that suspiciously does not include earth…
and think to yourself “Wow, Pluto is so much farther out from the sun than the Earth is. The solar system is so massive!”. And while you would be correct in your statement, the orbits of the sun’s outer planets (and dwarf planets) pale in comparison to the true extent of our solar system. Enter: the OORT CLOUD.
Actually, the Oort Cloud is going to have to wait. First, we’re going to have to cover comets. For a comet to show its characteristic tail, it has to pass (relatively) close to the sun. This implies that its orbit must be highly elliptical so that it can be near the sun for a short period of time before moving far enough away that it reverts to its less aesthetic ball-of-ice-and-rock form.
Everyone knows about Halley’s comet, which becomes visible from Earth every 76 years. Combining this lengthy period with the above fact that comet orbits must be very elliptical, one can imagine that Halley’s comet is, at its furthest extent away from the sun, far away. An in fact it manages to reach a bit farther than the orbit of Neptune before crashing back toward the sun.
But, in the grand scheme of things, Halley’s comet actually has a fairly short period. The famous Hale-Bopp comet has a period of over 2500 years and, as you might guess, reaches much farther away from the sun than Halley’s comet: 183 AU, or roughly 6 times farther than Neptune’s Aphelion.
But wait, there’s more! This unassuming ball of rock:
is Sedna, a minor planet whose aphelion is 936 AU, or 30 times Neptune’s aphelion.
But even beyond Sedna, there is the Oort Cloud. The Oort Cloud is a theoretical cloud of gas and icy bodies which exists at the very edge of the Sun’s gravitational influence. This cloud is conjectured to exist at up to 200,000 AU away from the sun. In other words, the outer reaches of the Oort Cloud, should it exists according to these projected specifications, would be over six thousand times farther away from from the sun is than Neptune. This is the true extent of our solar system, beyond which point the sun’s gravity is no longer sufficient to pull bodies along with it as it wanders through the galaxy.
Comparison of the inner solar system versus the inner Oort Cloud.
When it comes to taking meaningless BuzzFeed quizzes or looking at Tumblr text posts about my zodiac sign, I am guilty as charged. There’s something satisfying about taking a quiz that tells you which limited edition Oreo flavor you are by your zodiac sign! (I’m apparently Gingerbread. Who knew?) I even know some people who see these astrology quizzes as fun personality quizzes. But although it may be fun, these quizzes ultimately hold no other purpose or truth other than being an excellent mode of procrastination.
There are twelve zodiac signs, with each sign corresponding to the placement of the sun at one’s date of birth. (Note: There is a 13th sign—Ophiuchus, but it doesn’t align with the 12-month calendar. So ancient astrologers ignored it because that’s the best way to solve our problems, apparently.) As mentioned in my introductory post, my sun sign is supposed to be Libra. This means that the constellation Libra was behind the sun on my date of birth—September 28th. Except it wasn’t! As it turns out, due to the precession of Earth’s axis, the position of the stars relative to the ecliptic have moved back by approximately a month. As shown in the image below, Earth wobbles (like a top) as it rotates around its axis, which is tilted 23.5 degrees. This cycle of precession takes approximately 26,000 years! Because the signs are based in the positions of the Sun among the constellations as they were ~2000 years ago, the axis has moved through approximately a 1/13th of the precession cycle, which explains why our zodiac signs are off by approximately a month!
One of the most beautiful aspects
of astronomy is learning about our place in the vast universe. Although we
humans often feel as if we are the center of the universe, we are so tiny and
so young compared to the whole cosmos.
At around 20 years of age, most of us probably feel as if we are relatively grown up, and that we have already experienced quite a bit of life. But that length of time is nothing compared to the 14 billion years the universe has been in existence. Consider this: if the entire age of the universe were condensed into a year, each of us would have been born only 0.05 seconds ago! Think about that the next time you feel old!
It is also incredibly difficult to imagine a world without
humans, yet we as a species have only been around for the last two minutes of
this cosmic year…and all our history has taken place in just the last 30
seconds! So far, humanity is but a tiny blip compared to the existence of the
universe.
But just how small are we? We humans feel pretty big on this Earth – after all, we’re larger than most of the other species on our planet, and with our own intellect we’ve constructed sprawling cities and towering skyscrapers. We can fly halfway around the planet in a matter of hours. Yet the Earth is minuscule on a cosmic scale: one million Earths could fit inside the Sun, which is just a medium-sized star. It takes light from the Sun eight minutes to reach us, despite it being the fastest thing in the universe. For comparison, the next closest star (Alpha Centauri) is 4.4 light-years away. We have already far exceeded the distance humans could expect to travel within a lifetime, but it is still nothing compared to the diameter of our Milky Way Galaxy: 100,000 light-years. There are still 2.5 million light-years between the Milky Way and its nearest neighbor, the Andromeda Galaxy; both are part of a collection known as the Local Group, which is 10 million light-years in diameter. That is only a fraction of the diameter of the Observable Universe (the parts of the universe from which light has reached us), which is 93 million light-years. We humans are negligible on this incredible scale. In number, too, our population of seven billion does not compare to the approximately billion trillion stars in the observable universe, or even the 100 billion stars in our Milky Way Galaxy!
Perhaps understanding these scales of time and size will help you gain a deeper appreciation for the marvels of the universe. And if you are having a bad day, just remember how small and insignificant your problems are compared to the grandeur of the cosmos!
A comparison of the Earth and other round objects in the Solar System. Note how small our planet is, even on this scale!
Our universe is so vast it is simply mind blowing. The true nature of the size of our universe can be understood by examining powers of ten. We begin with a picnic scene one meter wide viewed from one meter away. Every 10 seconds we will look 10 times further away and our view of the picnic will be 10 times wider. Zoom out to 10^2 meters, the distance a man can run in 10 seconds. Back up even further to 10^3 meters, the distance a race car can travel in 10 seconds. Now at 10^4, the distance a supersonic airplane can travel in 10 seconds. At only 10^6 do you begin to see the entire sphere of the earth. At 10^7, background stars are so far away that they do not yet appear to move. At 10^13 we see our entire solar system, and at 10^14 our solar system shrinks to one bright point in the distance, and our sun is now merely just one star among the million others that scatter our galaxy. At 10^20, we reach the outskirts of our galaxy and begin to see the spiral shape of the Milky Way. At 10^21 we see the clouds of Magellan and other satellite groups, and now one million light years away at 10^22 we begin to see groups of galaxies. Fast-forward to 10^24, the largest view of the universe that has been discovered by man. At this vantage point in space, galaxies start look like dust. There appears to be more emptiness than matter, but this emptiness is normal, “as the richness of our own neighborhood is the exception” (Powers of Ten). Centuries ago, people considered earth to be astronomically unique. We know now that is incorrect, that earth is no different from the millions of other habitable planets in our universe. Why is it then, that many people still consider human life the most important thing in the universe? At 10^24 meters away from our picnic scene, when galaxies look like specks of dust littered throughout the universe, you begin to realize how insignificant human life is in comparison to the grand scheme of things. However, many people in contemporary society tend to forget this fact, as their inflated ego has led them to believe that humans are the most important thing out of everything in our vast universe. Knowing just truly large our universe is can be quite humbling, and I believe that is an important fact to be mindful of.
