“The only reason for time is so that everything doesn't happen at once.”
~ Albert Einstein
Consider a measuring tape, one of those soft cloth yellow ones used in tailor shops—perhaps a tailor shop in Boston. If this measuring tape represented time, instead of distance, perhaps we might decide one inch equals a century—100 years. For most of us, if we’re lucky, our lives will span somewhere between three quarters of an inch and an inch. Make a mark, anywhere on the tape, to indicate today.
Looking back in time on our timeline measuring tape, the American Civil War, 1861 – 1865, occupies a tiny sliver of an inch, about one-and-a-half inches left of our mark. The Declaration of Independence was signed in the summer of 1776, about two-and-one-third inches to the left of our mark. Columbus landed on Hispaniola in 1492, a little over five inches to the left of our mark.
Christ lived 20 inches left of our mark. The Battle of Thermopylae, in the fall of 480 BC, in which a small Greek force, led by Leonidas and his 300 Spartans, confronted the invading Persian army, took place about 25 inches, just over two feet, left of our mark.
Stonehenge was built on the southern plains of England in about 3000 BC, about four feet to the left of our mark. The first written records of history began being kept about 3700 BC, or four-and-three-quarters feet left of our mark, about the same time the last woolly mammoth died.
Mesopotamian civilization arose and flourished during the period 8000 BC – 7000 BC, seven to eight feet left of our mark. About this same time, the last saber-toothed cat became extinct. Ten feet left of our mark, the last Ice Age ended. Twelve feet left of our mark, what is now the Sahara Desert was moist and fertile. The earliest permanent human settlement (in what is now the Czech Republic) was established about 23,000 BC, about 19 feet left of our mark.
Anatomically-modern Homo Sapiens first appeared in Africa about 120,000 years ago, or 100 feet (six feet longer than an NBA basketball court) left of our mark. Homo Sapiens and Homo Erectus diverged on the evolutionary chart about 250 feet left of our mark (Homo Erectus had colonized what is now modern Eurasia about 416 feet left of our mark).
Somewhere between 660 and 1300 feet (two to four football fields) left of our mark, Homo Erectus first learned how to control and use fire.
The genus Homo first emerged 2.5 million years ago, approximately 2100 feet, or about four tenths of a mile, left of our mark. The Hominid family emerged somewhere between 12 and 18 million years ago, or between two and three miles left of our mark.
The first grasses emerged on our planet about three miles left of present day. The first elephants appeared about four miles left of our mark. Cats began evolving almost five-and-a-half miles to the left, and canines at about six-and-a-third miles. Seven-and-three-quarter miles left, whales returned to the Earth’s oceans from land. Nine-and-a-half miles left, primates began evolving. Our timeline tape is still within the greater Boston metro area.
The last dinosaurs became extinct 65 million years ago, a little over 10 miles to the left of our mark. The Himalayas began to reach for the sky at about the same time, as the Indian subcontinent began its tectonic collision with Asia’s underbelly. The first mammals debuted about 31 miles left of today on our timeline tape. The age of the dinosaurs began about 250 million years ago, almost 40 miles to the left of our mark, or a few miles west of Worcester.
The first lunged organisms emerged about 420 million years ago, or about 66 miles to our left. The original vertebrates emerged about 85 miles left of our mark. The first complex, multi-celled life forms appeared about 600 million years ago, or 95 miles left. The very first life on Earth likely appeared somewhere in the range of 600 to 650 miles left of our mark. If our present day is in Boston, and each inch represents a century, life began somewhere around Cleveland (I hope no one from there interprets these words out of context!).
Our planet, Earth, formed about 4.5 billion years ago, or about 710 miles to the left. Our Solar System coalesced about 730 miles left of our mark. Scientific consensus suggests the universe began with The Big Bang around 13.5 billion years ago, or about 2150 miles left of our mark—or roughly the distance between Boston and Billings, Montana.
Getting back to the mark on our (extremely long) measuring tape in Boston, what about the part of the tape to the right—our future? What lies ahead? There seems to be a growing consensus among astronomers—particularly among specialists in stellar evolution—that our Sun will continue to get brighter, more intense (as it has for its first 4.5 billion years). Some scientists project that a billion years from now, our Sun will be 10 percent brighter. Our oceans will boil away and, at some point, far out to the right along our measuring tape, our Earth will no longer be capable of hosting life as we know it. At perhaps 5.5 billion years, our Sun will run out of fuel in its core. As it begins to burn hydrogen in the surrounding layers, our Sun will expand into a red giant. Somewhere around 7.5 billion years hence, our long-since dead planet Earth will vaporize as it spirals into our engorged, red Sun.
This future sounds bleak. Keep in mind, however, Homo Sapiens have only been around for about 120 thousand years, or about 100 feet of our measuring tape—just a bit longer than the Boston Celtics’ home court. We didn’t even begin recording our history until less than five feet ago. Even if our Earth only supports life for another 500 million years, that doomsday is still farther into our future than the advent of lunged creatures is into our past. 500 million years is about 80 miles to the right of our mark, a nice drive up the coast to near Portland, Maine. A lot will happen on that journey.
Sunday, March 28, 2010
Our Place in Space
“A person’s a person, no matter how small”
- Horton the Elephant, Horton Hears a Who, Dr Seuss
I used to judge elementary and middle school science fairs on occasion. Aside from exhibits showing how carbonated soda would corrode steel nails, the most ubiquitous project theme seemed to be the tried and true model of our Solar System. Oh, what wondrous concoctions and contraptions they were, fashioned almost universally from colorfully painted and carefully decorated plastic foam balls of various sizes and a rainbow array of pipe cleaners and wire coat hangers. The more imaginative ones would incorporate movement, the planets able to revolve around the Sun. Without exception, they all fit within the allotted space for a project—certainly within a square yard or so. I always thought the youngsters, at least the geeky ones, would get a kick out of knowing how big their projects would be if they were modeled to scale…
Let’s say the Earth, which is about 8000 miles in diameter, were approximately the size of a large pea—a hair bigger than a quarter inch in diameter. Our Moon, about one quarter the diameter of earth, would then be slightly less than the size of the tiniest of baby peas. Put in proper reference to one another, baby pea Moon would be placed in orbit around big pea Earth at a distance of about 9 inches.
Using the same scale, our Sun, which is about 870,000 miles in diameter, would be a very large beach ball, about three feet in diameter. Earth orbits the Sun at a distance of 93 million miles. Using our big pea Earth and our big beach ball Sun, we would need to place them at the opposite goal lines of a football field to appropriately model the distance—about a hundred yards apart.
How big is our Solar System? Heck, what comprises our Solar System? Let’s go with the latest thinking, which excludes Pluto as an actual planet. Yes, if you have not heard, Pluto was demoted to dwarf planet status by the International Astronomical Union in 2006. So, all that stuff you learned about nine planets? Throw it away. (This was really bad news for plastic foam ball manufacturers, who saw an immediate ten percent slump in annual sales and were forced to compensate by launching an all-out marketing blitz promoting miniature hand-made snowmen during the winter holiday season, but I digress.)
We now consider Neptune, the eighth and final planet, to be the farthest planet from our Sun. Neptune is about 30,000 miles in diameter, just under four times the diameter of Earth. Compared with our large pea planet, Neptune would be a small cherry tomato (only blue). Neptune orbits the sun at an average distance of about 2.8 billion—yes that’s billion—miles. In our model, our cherry tomato Neptune would need to be placed about 1.73 miles away from our beach ball Sun.
So, if our science fair project model is going to be accurate, we’re going to need a pretty big room to put it in—a room three and a half miles across to accommodate the diameter of our system!
There are regions of the Solar System well beyond Neptune, such as the Kuiper Belt. This cloud of orbiting objects, much like the Asteroid Belt between Mars and Jupiter, only much larger and more massive, is the place to which poor Pluto was demoted. Including this outer region in our model would roughly double its size to seven miles in diameter.
Let’s not stop our journey just yet, shall we? Let’s take big step back—one giant leap for humankind, if you will—and imagine our Sun, our star, as a single grain of sand, say about one thirty-second of an inch in diameter. In that scale, you’d have to have some pretty amazing vision (probably a microscope) to see the tiny speck that would be Neptune, in its orbit a little over nine feet away from our grain of sand Sun. So, with our Sun as a tiny grain of sand at the center, our Solar System would be a circle a little over 18 feet across. If we included the Kuiper Belt region, our circle would be about 30 to 35 feet across.
Other than our Sun, the nearest star to us is Alpha Centauri, the third brightest star in the night sky (behind Sirius and Canopus) and visible in the Southern Hemisphere as the brightest star in the constellation Centaurus. Alpha Centauri is actually a system of three stars in close proximity to each other, all sharing a complex gravitational and orbital arrangement. This star system is approximately 4.37 light years away from our Sun. That’s how far light, travelling at 186,000 miles per second (about 5.88 trillion miles per year), will travel in about four years and four-and-a-half months, which is about 25.8 trillion miles.
So, in our new model, Alpha Centauri would be represented by three tiny grains of sand. And how far would this small collection of sand grains be from the sand grain that is our own Sun, the 18-foot circle that is our Solar System? 16 miles away! We, indeed, live in a sparsely populated neighborhood.
Our galaxy, the Milky Way, is a spiral disc, the arms and center of which contain approximately 200 billion stars (and perhaps as many as 400 billion). This disc is about 100,000 light years across (that’s 100,000 multiplied by 5.88 trillion miles, folks). Still using our grain of sand—a single tiny grain of sand—as our Sun, our galaxy would be 366,000 miles across!
Perhaps our scale is too big to fathom this. Let’s take another step back. Let’s say our entire solar system, about 5.6 billion miles in diameter (using Neptune’s orbit as the outer limit while fully acknowledging the true Solar System extends far beyond that), is the size of a dime, about five eighths of an inch in diameter. The Alpha Centauri system is now about 240 feet away. In this new scale, our galaxy would still be about 1040 miles across! Our Solar System, our little dime, would be about 27 miles from the center of our galaxy.
Head hurt? Let’s take one more step back, shall we? Let’s say our entire home galaxy, our Milky Way, all 100,000 light years across (100,000 times 5.88 trillion miles), is now just a dime. Scientists agree there are billions of galaxies in the observable universe—billions of them. Excluding the Large and Small Magellanic Clouds (small galaxies associated with the Milky Way and visible in the Southern Hemisphere), our nearest galactic neighbor is Andromeda. Although less massive than our own galaxy, scientists have estimated Andromeda contains as many as a trillion stars and is slightly larger than twice the diameter of the Milky Way, which would make it about the size of a fifty-cent piece in our final model. This fifty-cent piece Andromeda would be positioned about fifteen-and-a-half inches from our dime Milky Way.
And, so, we come to the size of our universe (not to mention well beyond my outer limit to discuss this topic with any confidence—well past time to scare up an astrophysicist). Here, there is broader disagreement as to size; however, the mainstream scientific community seems to accept that the visible universe is a sphere approximately 92 billion light years in diameter. I’m not sure exactly where our Milky Way dime fits into this universe. Our study—our understanding—of the limits of our universe is necessarily Milky Way centric. So, if our dime were at the center of the visible (to us, humankind) universe, our universe would be a sphere about nine miles in diameter.
Feel small? I do. Maybe it’s time we stick together and love each other more.
- Horton the Elephant, Horton Hears a Who, Dr Seuss
I used to judge elementary and middle school science fairs on occasion. Aside from exhibits showing how carbonated soda would corrode steel nails, the most ubiquitous project theme seemed to be the tried and true model of our Solar System. Oh, what wondrous concoctions and contraptions they were, fashioned almost universally from colorfully painted and carefully decorated plastic foam balls of various sizes and a rainbow array of pipe cleaners and wire coat hangers. The more imaginative ones would incorporate movement, the planets able to revolve around the Sun. Without exception, they all fit within the allotted space for a project—certainly within a square yard or so. I always thought the youngsters, at least the geeky ones, would get a kick out of knowing how big their projects would be if they were modeled to scale…
Let’s say the Earth, which is about 8000 miles in diameter, were approximately the size of a large pea—a hair bigger than a quarter inch in diameter. Our Moon, about one quarter the diameter of earth, would then be slightly less than the size of the tiniest of baby peas. Put in proper reference to one another, baby pea Moon would be placed in orbit around big pea Earth at a distance of about 9 inches.
Using the same scale, our Sun, which is about 870,000 miles in diameter, would be a very large beach ball, about three feet in diameter. Earth orbits the Sun at a distance of 93 million miles. Using our big pea Earth and our big beach ball Sun, we would need to place them at the opposite goal lines of a football field to appropriately model the distance—about a hundred yards apart.
How big is our Solar System? Heck, what comprises our Solar System? Let’s go with the latest thinking, which excludes Pluto as an actual planet. Yes, if you have not heard, Pluto was demoted to dwarf planet status by the International Astronomical Union in 2006. So, all that stuff you learned about nine planets? Throw it away. (This was really bad news for plastic foam ball manufacturers, who saw an immediate ten percent slump in annual sales and were forced to compensate by launching an all-out marketing blitz promoting miniature hand-made snowmen during the winter holiday season, but I digress.)
We now consider Neptune, the eighth and final planet, to be the farthest planet from our Sun. Neptune is about 30,000 miles in diameter, just under four times the diameter of Earth. Compared with our large pea planet, Neptune would be a small cherry tomato (only blue). Neptune orbits the sun at an average distance of about 2.8 billion—yes that’s billion—miles. In our model, our cherry tomato Neptune would need to be placed about 1.73 miles away from our beach ball Sun.
So, if our science fair project model is going to be accurate, we’re going to need a pretty big room to put it in—a room three and a half miles across to accommodate the diameter of our system!
There are regions of the Solar System well beyond Neptune, such as the Kuiper Belt. This cloud of orbiting objects, much like the Asteroid Belt between Mars and Jupiter, only much larger and more massive, is the place to which poor Pluto was demoted. Including this outer region in our model would roughly double its size to seven miles in diameter.
Let’s not stop our journey just yet, shall we? Let’s take big step back—one giant leap for humankind, if you will—and imagine our Sun, our star, as a single grain of sand, say about one thirty-second of an inch in diameter. In that scale, you’d have to have some pretty amazing vision (probably a microscope) to see the tiny speck that would be Neptune, in its orbit a little over nine feet away from our grain of sand Sun. So, with our Sun as a tiny grain of sand at the center, our Solar System would be a circle a little over 18 feet across. If we included the Kuiper Belt region, our circle would be about 30 to 35 feet across.
Other than our Sun, the nearest star to us is Alpha Centauri, the third brightest star in the night sky (behind Sirius and Canopus) and visible in the Southern Hemisphere as the brightest star in the constellation Centaurus. Alpha Centauri is actually a system of three stars in close proximity to each other, all sharing a complex gravitational and orbital arrangement. This star system is approximately 4.37 light years away from our Sun. That’s how far light, travelling at 186,000 miles per second (about 5.88 trillion miles per year), will travel in about four years and four-and-a-half months, which is about 25.8 trillion miles.
So, in our new model, Alpha Centauri would be represented by three tiny grains of sand. And how far would this small collection of sand grains be from the sand grain that is our own Sun, the 18-foot circle that is our Solar System? 16 miles away! We, indeed, live in a sparsely populated neighborhood.
Our galaxy, the Milky Way, is a spiral disc, the arms and center of which contain approximately 200 billion stars (and perhaps as many as 400 billion). This disc is about 100,000 light years across (that’s 100,000 multiplied by 5.88 trillion miles, folks). Still using our grain of sand—a single tiny grain of sand—as our Sun, our galaxy would be 366,000 miles across!
Perhaps our scale is too big to fathom this. Let’s take another step back. Let’s say our entire solar system, about 5.6 billion miles in diameter (using Neptune’s orbit as the outer limit while fully acknowledging the true Solar System extends far beyond that), is the size of a dime, about five eighths of an inch in diameter. The Alpha Centauri system is now about 240 feet away. In this new scale, our galaxy would still be about 1040 miles across! Our Solar System, our little dime, would be about 27 miles from the center of our galaxy.
Head hurt? Let’s take one more step back, shall we? Let’s say our entire home galaxy, our Milky Way, all 100,000 light years across (100,000 times 5.88 trillion miles), is now just a dime. Scientists agree there are billions of galaxies in the observable universe—billions of them. Excluding the Large and Small Magellanic Clouds (small galaxies associated with the Milky Way and visible in the Southern Hemisphere), our nearest galactic neighbor is Andromeda. Although less massive than our own galaxy, scientists have estimated Andromeda contains as many as a trillion stars and is slightly larger than twice the diameter of the Milky Way, which would make it about the size of a fifty-cent piece in our final model. This fifty-cent piece Andromeda would be positioned about fifteen-and-a-half inches from our dime Milky Way.
And, so, we come to the size of our universe (not to mention well beyond my outer limit to discuss this topic with any confidence—well past time to scare up an astrophysicist). Here, there is broader disagreement as to size; however, the mainstream scientific community seems to accept that the visible universe is a sphere approximately 92 billion light years in diameter. I’m not sure exactly where our Milky Way dime fits into this universe. Our study—our understanding—of the limits of our universe is necessarily Milky Way centric. So, if our dime were at the center of the visible (to us, humankind) universe, our universe would be a sphere about nine miles in diameter.
Feel small? I do. Maybe it’s time we stick together and love each other more.
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