Being an amateur stargazer, I have to confess that very few sights on this planet can inspire more amazement and awe from me than the sight of the evening sky after sunset when twilight begins to deepen into night and the very first of our world's nearest heavenly neighbors begin to appear in our sky above.
Going outside at night and watching the moon rise, the planets of our Solar System appear, and thousands of visible stars and galaxies appear overhead in the night sky never ceases to amaze us stargazers.
Even the brightest star known to us, our own bright Sun that we see practically every clear, mostly cloudless daytime from sunrise to sunset, is a wonderful miracle in the heavens that most people seemingly take for granted because its a constant companion.
From our perspective standing here on our good Earth, everything in the heavens appears to be fixed -- aside from our lovely moon and the five visible "wanderers" that we can see with the naked eye.
However, outside of our visual range, our planet travels at an incredible speed of rotation every single day, and in orbit around the Sun. The planets of the solar system also cover distances that might seem surprisingly fast to most of us observing them. Our own bright Sun also travels at insanely fast speeds around our own Milky Way Galaxy.
The reason we don't readily notice this is because the space beyond our planet is so very vast, its nearly incomprehensible to imagine. The distances involved are so long that we cannot possibly measure them simply by miles.
Today, I'm going to tell y'all just how fast and how far we travel. Y'all better buckle up because this is gonna blow your minds.
The Sun, Earth, & The Moon
At the center of our solar system is our own beautiful Sun and this is where our journey begins.
Our Sun is a bright G-type main-sequence star (or G-Type Star) that comprises about 99.86% of the mass of the Solar System. The Sun itself rotates at an average of about 28 days, although this varies at different latitudes since the Sun isn't a solid body but rather a giant ball of gaseous plasma. Its width is measured at approximately 864,000 miles, or 109 times that of Earth, with its mass measured at about 330,000 times that of the Earth.
To give you an idea of how huge that actually is, let me explain to y'all the exact speed and distance it takes our Earth to travel in its orbit around the Sun in a single year.
Our planet Earth is the third planet out from the Sun and the fifth largest planet in our Solar System. The mean diameter of the Earth (the distance from one side to the other through Earth's center) is about 7,926 miles across. However, the interesting thing to realize here is that Earth is not quite a total sphere.
Our planet bulges out a bit more around the equator than it does at the poles because of its rotation caused by the flattening at the poles, making it a slight oblate spheroid. Earth is therefore slightly smaller when measured between the North and South Poles (or the meridional circumference), which gives a diameter of 7,907 miles -- or a difference of about 20 miles. Earth's circumference (the distance all the way around the equator) is around 24,900 miles.
Earth itself rotates on its axis in space counter-clockwise approximately once every 23 hours, 56 minutes, and 4 seconds in a standard 24 hour day; spinning at an incredible speed of about 1,037 miles and hour. Because Earth spins steadily, as well as moves at a constant rate in orbit around the sun, we have the gravity that holds us all tightly in its grip to this beautiful blue world we all know and love.
The mean distance from the surface of the Sun to the surface of the Earth is around 93 million miles. This distance is measured by astronomers as one astronomical unit (AU).
Since the Earth revolves in an oval shaped path (or elliptical orbit) around the Sun, rather than an even circular path, the exact distance varies ranging between the extremes of perihelion (closest approach) in January and aphelion (most distant orbital position) in July. This actually puts Earth’s orbital distance from the Sun from between approximately 91.5 million to 94 million miles respectively.
Earth travels about 1.6 million miles daily at about 68,000 miles per hour in its orbit around the sun. Over the span of the 365.26 days that makes up a single year, our planet Earth travels around 584 million miles in its orbit around the Sun.
That's pretty incredible huh?
Next to us in the night sky is our own beautiful lunar companion, Luna -- better known as simply the Moon.
The Moon's mean radius is 1,079.6 miles wide with an overall diameter of 2,159 miles, or about a little less than one-third the width of the Earth. Because of tidal forces that keep the Moon from rotating, one side always faces the Earth as it circles us in its monthly rotation.
Like the Earth travels around the sun in an oval-shaped path, the Moon also travels in an oblong orbit. When the Moon is the farthest away from Earth (or at its Apogee), it’s 252,088 miles away, while at it's closest approach (or at its Perigee), the Moon is 225,623 miles away -- the equivalent of about 32 Earths distant.
The Moon makes a complete orbit around the earth every 27.3 days, or approximately 13 times in a calendar year. Given the distance from the Earth and speed, the Moon travels a full distance of 1,423,000 miles an hour at a speed of 2,288 miles per hour to complete this orbit. Because of the rotation of the Earth and our own perspective standing on the surface, we humans do not perceive just how fast this is from our observations -- but its pretty fast!
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| The sunlight we
see here on Earth takes approximately 8 minutes and 20 seconds to travel the 93 million miles from the surface of the Sun through the gulf of space to reach Earth. |
The Speed Of Light
Our Solar System is so large in sheer scale that using ordinary units of measurement like feet, or miles, simply won't do. On average, Pluto -- the farthest planet in our solar system (and yes, it's still a planet even if its a small one!) has a mind-blowing average mean distance of 3.6 billion miles from the Sun and takes a whopping 247.9 years to orbit the Sun just once!
In order to measure the size of our Solar System more accurately we must use the speed of light as our yard stick.
We use this because the speed of light is constant throughout the universe, traveling in the vacuum of space at an incredible speed of about 186,282 miles per second -- or about 670.6 million miles per hour. To put that in perspective, if you could physically travel at the speed of light, you could go around the Earth a mind-blowing 7.5 times in one second; or travel from Earth to the Moon in about 1.5 seconds.
Now that's ludicrous speed folks, and theoretically nothing can move faster than light outside of science fiction.
One light-minute is about 11,160,000 miles. One light-hour is 671 million miles -- roughly the distance between the sun and halfway between the planets Jupiter and Saturn in our Solar System. One light-day is 16.1 billion miles -- more than four times the distance between the Sun and Pluto. Finally, one light-year is a whopping 5.8 trillion miles!
Standing on the surface of the Earth, when we look up at the bright yellow Sun in the sky and the light that makes up the daytime hours; that light we see takes approximately 8 minutes and 20 seconds to travel the 93 million miles from the surface of the Sun through the gulf of space to reach Earth. So, one AU is a bit more than 8 light-minutes in distance.
From the 3.6 billion miles from Sun to Pluto at the far end of the Solar System, it would take sunlight about 5 hours and 40 minutes to cover that distance, or roughly about 39.5 AU.
Now when measuring distances outside of our Solar System, we must turn to another unit of measuring distances called parsecs. A parsec is approximately equal to 3.26 light-years, or 19.2 trillion miles (206,000 AU). A distance of 1,000 parsecs (or 3,262 light years) is called a kiloparsec (KPC).
Beyond our Solar System the nearest stars are in the Alpha Centauri system, a triple star system made up of three stars: Rigil Kentaurus (Centauri A), Toliman (Centauri B), and the small, red dwarf star Proxima Centauri (Centauri C). The closest of these stars, Proxima Centauri, sits at about 4.24 light-years (or 1.30 parsecs) from the Sun.
To put another way, the light from our stellar next door neighbors that we would see standing her on Earth took just over four years to reach us. Also, if we tried to measure that in standard miles, that would be roughly 24,000,000,000,000 miles away! Now that's a lot of zeroes, y'all.
The Milky Way And Beyond
Our entire Solar System -- our Sun with its family of planets, asteroids, and comets -- orbits around the center of the large Milky Way Galaxy.
The Milky Way itself is a large barred spiral galaxy believed to be about 100,000 light years across (30.66 kiloparsecs) and made up of an estimated 100 - 400 billion stars, nebulae, and exoplanets.
The Solar System itself does not lie near the center of our Galaxy, rather it lies about 29,000 lights years (or 8 kiloparsecs) from the Galactic Center on what is known as the Orion-Cygnus Arm of the Milky Way.
Our Sun and Solar System move in a huge orbit around the center of the Milky Way Galaxy at about about 500,000 miles an hour. That's roughly about 12,500 miles in 90 seconds. Because the Milky Way is such a big place, even at this ludicrous speed, it takes our Sun and Solar System approximately 225-250 million years to complete one single orbit around the galaxy’s center. To put that in perspective, that's roughly Earth's early-to-mid Triassic Period when the first dinosaurs appeared till the present day! This amount of time is referred to as a cosmic year, or a galactic year.
The Milky Way itself travels through the Universe at large at an astonishing 1.3 million miles an hour!
Outside of our galaxy the nearest local bodies are the two Magellanic Clouds that orbit the Milky Way. The Large Magellanic Cloud (LMC) is approximately 163,000 light-years (49.9 kiloparsecs) away while the Small Magellanic Cloud (SMC) is approximately 206,000 light-years (63 kiloparsecs) away.
Beyond the Magellican Clouds the closest neighboring galaxy is the Andromeda Galaxy (Messier 31, or NGC 224). Like the Milky Way, it is also a barred spiral galaxy approximately 2.5 million light years (770 kiloparsecs) from our Sun. The Andromeda Galaxy has an estimated diameter of about 220,000 light years (67 kiloparsecs).
On and interesting note, due to the ever expanding nature of the Universe, the Andromeda Galaxy is currently racing toward our own Milky Way Galaxy at an estimated speed of about 70 miles per second and the two galaxies are expected to collide with each other sometime in about 4-5 billion years from now.
Once we move further out into the Universe itself, the distances become even more daunting. Astronomers typically express the distances between neighboring galaxies and galactic clusters in megaparsecs (MPC) and gigaparsecs (GPC) the largest units of length commonly used. A megaparsec is one million parsecs (or 3,260,000 light-years) and a gigiparsec is one billion parsecs (or 3.26 billion light-years)!
The most distant and probably oldest known galaxy in the observable Universe is GN-z11 approximately 32 billion light-years (or 9.75 gigaparsecs) away from the Milky Way in a Universe that is estimated to be 93 billion light-years (or 28 gigaparsecs) across!
Now that's truly incredible to think about, y'all!
Conclusion
Going about our daily lives we can easily take for granted that we are traveling through this galaxy and universe of ours, propelled at incredibly ludicrous speeds.
Looking up at the night sky, seeing the heavens above us in the sky dome, its truly a humbling experience knowing that in all of that infinity we are all of us merely a small speck of sand in an insanely large ocean of stars and galaxies -- and perhaps far more than we can readily observe even with our best astronomical instruments.
Probably the only thing more infinite than our known Universe is the human imagination itself.
I hope y'all have enjoyed this post, have a wonderful Dixie evening and y'all come back now, ya hear!
We use this because the speed of light is constant throughout the universe, traveling in the vacuum of space at an incredible speed of about 186,282 miles per second -- or about 670.6 million miles per hour. To put that in perspective, if you could physically travel at the speed of light, you could go around the Earth a mind-blowing 7.5 times in one second; or travel from Earth to the Moon in about 1.5 seconds.
Now that's ludicrous speed folks, and theoretically nothing can move faster than light outside of science fiction.
One light-minute is about 11,160,000 miles. One light-hour is 671 million miles -- roughly the distance between the sun and halfway between the planets Jupiter and Saturn in our Solar System. One light-day is 16.1 billion miles -- more than four times the distance between the Sun and Pluto. Finally, one light-year is a whopping 5.8 trillion miles!
Standing on the surface of the Earth, when we look up at the bright yellow Sun in the sky and the light that makes up the daytime hours; that light we see takes approximately 8 minutes and 20 seconds to travel the 93 million miles from the surface of the Sun through the gulf of space to reach Earth. So, one AU is a bit more than 8 light-minutes in distance.
From the 3.6 billion miles from Sun to Pluto at the far end of the Solar System, it would take sunlight about 5 hours and 40 minutes to cover that distance, or roughly about 39.5 AU.
Now when measuring distances outside of our Solar System, we must turn to another unit of measuring distances called parsecs. A parsec is approximately equal to 3.26 light-years, or 19.2 trillion miles (206,000 AU). A distance of 1,000 parsecs (or 3,262 light years) is called a kiloparsec (KPC).
Beyond our Solar System the nearest stars are in the Alpha Centauri system, a triple star system made up of three stars: Rigil Kentaurus (Centauri A), Toliman (Centauri B), and the small, red dwarf star Proxima Centauri (Centauri C). The closest of these stars, Proxima Centauri, sits at about 4.24 light-years (or 1.30 parsecs) from the Sun.
To put another way, the light from our stellar next door neighbors that we would see standing her on Earth took just over four years to reach us. Also, if we tried to measure that in standard miles, that would be roughly 24,000,000,000,000 miles away! Now that's a lot of zeroes, y'all.
The Milky Way And Beyond
Our entire Solar System -- our Sun with its family of planets, asteroids, and comets -- orbits around the center of the large Milky Way Galaxy.
The Milky Way itself is a large barred spiral galaxy believed to be about 100,000 light years across (30.66 kiloparsecs) and made up of an estimated 100 - 400 billion stars, nebulae, and exoplanets.
The Solar System itself does not lie near the center of our Galaxy, rather it lies about 29,000 lights years (or 8 kiloparsecs) from the Galactic Center on what is known as the Orion-Cygnus Arm of the Milky Way.
Our Sun and Solar System move in a huge orbit around the center of the Milky Way Galaxy at about about 500,000 miles an hour. That's roughly about 12,500 miles in 90 seconds. Because the Milky Way is such a big place, even at this ludicrous speed, it takes our Sun and Solar System approximately 225-250 million years to complete one single orbit around the galaxy’s center. To put that in perspective, that's roughly Earth's early-to-mid Triassic Period when the first dinosaurs appeared till the present day! This amount of time is referred to as a cosmic year, or a galactic year.
The Milky Way itself travels through the Universe at large at an astonishing 1.3 million miles an hour!
Outside of our galaxy the nearest local bodies are the two Magellanic Clouds that orbit the Milky Way. The Large Magellanic Cloud (LMC) is approximately 163,000 light-years (49.9 kiloparsecs) away while the Small Magellanic Cloud (SMC) is approximately 206,000 light-years (63 kiloparsecs) away.
Beyond the Magellican Clouds the closest neighboring galaxy is the Andromeda Galaxy (Messier 31, or NGC 224). Like the Milky Way, it is also a barred spiral galaxy approximately 2.5 million light years (770 kiloparsecs) from our Sun. The Andromeda Galaxy has an estimated diameter of about 220,000 light years (67 kiloparsecs).
On and interesting note, due to the ever expanding nature of the Universe, the Andromeda Galaxy is currently racing toward our own Milky Way Galaxy at an estimated speed of about 70 miles per second and the two galaxies are expected to collide with each other sometime in about 4-5 billion years from now.
Once we move further out into the Universe itself, the distances become even more daunting. Astronomers typically express the distances between neighboring galaxies and galactic clusters in megaparsecs (MPC) and gigaparsecs (GPC) the largest units of length commonly used. A megaparsec is one million parsecs (or 3,260,000 light-years) and a gigiparsec is one billion parsecs (or 3.26 billion light-years)!
The most distant and probably oldest known galaxy in the observable Universe is GN-z11 approximately 32 billion light-years (or 9.75 gigaparsecs) away from the Milky Way in a Universe that is estimated to be 93 billion light-years (or 28 gigaparsecs) across!
Now that's truly incredible to think about, y'all!
Conclusion
Going about our daily lives we can easily take for granted that we are traveling through this galaxy and universe of ours, propelled at incredibly ludicrous speeds.
Looking up at the night sky, seeing the heavens above us in the sky dome, its truly a humbling experience knowing that in all of that infinity we are all of us merely a small speck of sand in an insanely large ocean of stars and galaxies -- and perhaps far more than we can readily observe even with our best astronomical instruments.
Probably the only thing more infinite than our known Universe is the human imagination itself.
I hope y'all have enjoyed this post, have a wonderful Dixie evening and y'all come back now, ya hear!
This blogger would like to offer a special thanks to the wonderful folks at earthsky.org and NASA for providing the information in this article.
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