Where Earth is in the Universe
Have You Ever Looked Up and Wondered; Where Are We?
Welcome Fellow Explorers
Hello reader, lets turn on our imaginations and strap ourselves to our office chairs or in whatever it is you are sitting on for a journey that begins right here on Earth. We are going to explore one of the great astronomical, cosmological, and quantifiable questions ever asked....
"Where is Earth in the Universe?"
To learn about where we are we will have to travel back in time to the very beginning of our universe and take a journey that will land us here in the present and then outward into the observable universe we see and detect with our modern day technology. From our own Solar System to the edge of time and space we will explore this question together and hopefully end up with at least a better understanding of where we are in the universe.
Geocentric Universe Model (Earth as the Center of Everything)
Where Are We Compared to Everything Else?
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When primitive men peered out from the safety of their caves and into the night sky filled with the glowing brilliance of a multitude of stars that make up the canopy above, I wonder if they pondered the same questions we do today. I mean when you look up at night at the visible stars that shine on the clearest evenings you can only wonder if they asked themselves that very question, "Where am I in the Universe?" But the actual number of stars in the sky is probably greater than all the sand grains on all the beaches of earth. Trillions of stars litter the universe in all directions.
To gather information from the stellar movements across the sky on observable nights and to create shapes of familiar gods and creatures the ancient astronomers named the pictures they saw as they connected stars and we call those images constellations. Sailors use the north star Polaris to guide their ships at night keeping her to the right when sailing west and left when heading east.
A Brief History of Mans Understanding of the Universe:
The Greek philosopher Aristotle theorized that the Earth was at rest in the center of the Universe and all the things we see in the heavens orbited around Earth. The astronomer Ptolemy used this theoretical principle to understand the movements in the heavens and his books were used for 1500 years. This model was called the Geocentric Model and was also adopted later on by the Catholic Church.
Galileo (1564 - 1642) discovered that Jupiter had four moons using a telescope he made himself. The moons showed that Earth was not at the center of all motion in the Universe. Galileo supported the theory set forth by Copernicus that the Earth actually circled the Sun. This got Galileo (a Catholic Priest) into trouble with the Church and he was placed under house arrest for the rest of his life.
How It All Began
In The Beginning The Earth Was Void and Without Form
Beyond the ink like blanket of night and the congregations of stars in the vast void we turn the dial of a radio or we switch on a television with only static. What we hear is the familiar hissing, that hissing is a microwave fingerprint revealing the violent distant past of our universe, made by a big bang at the beginning of time and space.
To know where we are in the universe we must look back at where we came from. Some 14.5 billion years ago all the mass and energy in the universe was compressed into an infinitely dense state heated to several trillion degrees. What followed was an expansion of energy a featureless mass of heat and energy rushed outward as matter and antimatter came into existence and annihilated one another giving the universe a push in its expansion. Matter tipped the scales in favor of a stable universe where we can exist. Since that initial Big Bang our universe has been expanding ever since.
In its infancy the Universe was a very hazy place and was formless. After a million years the background temperature of the universe dropped to (3k degrees above absolute -zero). Soon the strong force began to form nuclei which then captured electrons to create hydrogen and some helium. This helped the universe clear the heated froth of the after glow from the big bang and suddenly the universe gave birth to light as the first hydrogen stars ignited to life forcing back the cosmic haze.. Denser regions of heated gas pulled together through gravity and birthed into stars. Soon those stars formed into galaxies. We know that today's universe is still expanding. But we can see the background radiation of that ancient cosmic explosion called the Big Bang.
The matter of the universe collected into galaxy forms held together by the force of gravity. Gravities influence is felt all over the universe and integral to its structure. As we move outward from our own Galaxy and it's closest neighbors the Local Group we find ourselves in a tendril of galaxies strung into Super Clusters and the pattern repeats over and over like the nexus celluloid of a sponge's foamy surface.
The Solar System
The Planets and Beyond
Our first exploring points on our sojourn through the universe will be our Sun, the planets, asteroids, dwarf planets, and moons of our own Solar System. Put on some suntan lotion readers because we are headed 8 light minutes to the nearest star, our Sun. Here we look at our solar system and all it's dynamics and we learn about where we are locally in our solar system and you may be surprised at what you learn here in our stellar backyard.
Post Cards From the Edge - of the Solar SystemClick thumbnail to view full-size
The Sun Sol
Did You Know?
- Asteroids have moons! Asteroid moons orbit larger asteroids with more mass. In some cases the two asteroids are almost the same size.
- Lagrange points are locations in space where gravitational forces and the orbital motion of a body balance each other. Lagrange points are often used by NASA's JPL Mission Teams to help navigate space probes from Earth to the other planets.
- Most Science Fiction films and television shows depict the asteroid field as being a huge mass of many large and small objects made largely of stone and dust. These fields have to be navigated carefully because of proximity issues. But this couldn't be further from the truth about what our asteroid belt looks like
- The asteroid belt though populated by asteroid families are actually not very close together at all. These fields can contain many objects but they are weakly held together by gravity floating out there in the spacial expanse between Mars and Jupiter. This is also true for space junk. Yes it is true that there is LOTS of junk out there, but... It isn't like that scene in Wall-E where they have to bust through a cloud of coffee cups and cigarette butts.
The Inner Solar System
Our Star and her Four Dense Rocky Worlds:
Our Sun Sol:
The Sun is our home star. It has a mass of over 300,000 Earths. It is classified as a G2 yellow dwarf star. Our Sun produces nuclear fusion which releases tremendous amounts of energy through heat, light, radiation, electromagnetic energy, and electricity. Our Sun is in its prime of life phase being that it is still bright and this is a sign that it is in its main sequence phase of life. Hotter stars glow brighter where they dim with age and become red giants. Our Sun has a while before it uses up all its hydrogen and helium and ends its life as a white dwarf.
The Sun goes through cycles of activity called solar cycles. These happen when the Sun's electromagnetic field lines twist up because of the Sun's differential rotation. See the Sun is slighting squished because of the forces of mass and inertia. It is so massive that it's outer equator rotates faster than its polar caps. This causes the magnetic field lines to twist while the Sun rotates. Convection of electrified plasma below the Sun's surface creates large electrical currents that have a north and south dipole effect. Prominences break the surface of the Sun creating flux ropes. If you could see the entire filament we'd see that it is a large circle much like you see when you place a magnetic beneath a sheet of paper with iron filings on it. This process creates solar weather. When the convection happens Sun spots form, Soon flux ropes of plasma and electromagnetic energy rise off the surface of the sun and once in a while they become so energetic they explode outward in a solar flare sending electrified solar winds into the solar system.
The Four Inner Planets or the (Terrestrial Planets):
The four rocky worlds that call our inner solar system home are the Terrestrial Planets. They are dense worlds made mostly of rock, silicates, minerals, and metals like iron and nickle. Most of them have an atmosphere, (Venus, Earth, and Mars all have atmospheres) and all three have weathering on their surface. Most of them have impact craters from asteroid impacts. They also have tectonic surface features like volcanoes and fault lines.
Mercury 1st Planet from the Sun:
Mercury is the first planet we encounter as we venture outward into the solar system. At only 0.4 astral units or AU from the son it is the closest and smallest planet in the solar system being only a .055 Earths mass. Mercury has no moons and is dotted with impact craters, ridges, and rupes all caused by gravitational contraction from when Mercury was formed. Mercury has no atmosphere, if it did it was scoured clean by the solar winds produced by the Sun. Mercury is baked on its Sun facing side and freezing cold on the night side. Mercury's interior is mostly a thin mantle and a large iron core which makes up the bulk of planet. This iron core also produces an electromagnetic field much like Earths.
Venus 2nd Planet from the Sun:
Venus is very close in size to the Earth. Like the Earth it has a thick silicate mantle which surrounds an iron core, a thick atmosphere and geological activity. But there are striking differences between the Earth and Venus. Venus has no moon, and on Venus it is hot enough to melt led and the pressure at its surface is so dense it would destroy a space lander if we sent one. The Russians did just this with Venera 3 a reinforced lander which crash landed and was only able to take one picture before it was destroyed. Venus is covered in a thick layer of cloud which produces acid rain, Venus is so hot because of a run away greenhouse effect in the atmosphere, this makes Venus the hottest planet even above Mercury in the solar system. Venus has no magnetic field it is bombarded with solar energy constantly but because of its atmosphere it is absorbed and reflected back out into space. Though there has been no geologic activity detected on the planets surface it is believed to be geologically active since the atmosphere seems to be regularly replenished by gases released by what scientists think are volcanic eruptions.
Earth 3rd Planet from the Sun and Our Home:
Earth our home planet and the largest and most dense of all the inner planets and the one with current observable geological activity. It is also the only world we know of where life is known to exist. The reason is that the Earth orbits the Sun at just the right distance so that the element H2O or water can exist in liquid form. Because of this anomaly the chemical process to create life happened on Earth many millions of years ago. Life now inhabits almost every single environment on Earth. This solar orbit where life took hold is known as the Goldilocks Zone where conditions for life were just right. The earth is very geologically active with tectonic plate movements and volcanism. The Earth has a hydrosphere or ocean where much of the life on Earth exists. The oceans have tides and this phenomena caused by the Earth's Moon is what creates tide pools where it is believed in the primordial period before life collected the amino acid chains that began life. The Earth's atmosphere greatly differs from the other planets in the solar system. Life has altered the atmosphere significantly with 21% free oxygen. The Earth is also the only inner planet to have a large satellite (the Moon).
The Earth's Moon (Luna)
The Moon is our most familiar neighbor in space. It is also the only alien body our race has visited so far. We have sent probes to other worlds, but only on the Moon have men landed and walked upon its surface. The Moon is the largest satellite of any of the moonlit satellites in the Solar System as compared by its size to its host world Earth. It is also the second dense Moon in the Solar System after Jupiter's IO. It orbits in synchronous rotation with Earth showing Earth the same face and never its far side. It is the brightest observable object in the sky after the Sun; this happens even though its surface has a low reflectivity rate and is as dark as coal. It's importance has helped mankind keep track of months and the passage of years by it's regular cycles. It's gravitational power can be observed in the tidal forces seen in our oceans. It is said that this may have played a major role in evolution and beginning of life on Earth.
Mars 4th Planet from the Sun:
Mars is the 4th inner planet. It is smaller than Earth and Venus but it does possess and atmosphere made up of mostly carbon dioxide. The surface pressure is only 6.1 millibars or only .6 that of Earth's surface pressure. If you were stand on the surface of Mars your blood would boil as the gasses within you instantly began to be released from the lack of pressure. Mars has the largest mountain in the solar system Olympus Mons a long dead super volcano and it is also the host of the largest canyon in the solar system Valles Marineris which is as long as the continental United States. Mars is also the home of two satellites Deimos and Phobos both thought to be captured asteroids. Many astronomers now believe that Mars may have had water in its distant past. The Mars rovers Spirit, Opportunity, and Pathfinder have all found stones that show that at some time in their history were underwater. We do know that there is water ice trapped below the surface of Mars and in the polar ice caps. This has also been show in rock falls from canyon walls which show subterranean water ice in a permafrost layer. This and the fact that Mars has been shown to have methane in its atmosphere gives the Zeno-biologists oodles of hope that they may one day find microbial fossils or even living microorganisms living in underground colonies on Mars.
Ceres the Dwarf Planet:
Ceres is a dwarf planet (a very large asteroid that has enough mass to take on a rounded shape). Ceres is considered a dwarf planet since it does not orbit a planet but the Sun in a regular orbit.
The Asteroid Belt:
orbits between Mars and Jupiter. All asteroids excluding Ceres are labeled as small silicate, iron, and rocky objects. Asteroids in the asteroid belt are grouped into families based on their orbits. The asteroid belt also houses the main-belt comets which are believed to have helped kick start the water period on Earth and may have even helped in the chemistry it took to create life.
Humans have only walked on one other world:
On a personal note:
The opinions herein are the personal thoughts of the Author that wrote this article.
"The Moon has inspired mankind to keep looking up. I believe the Moon played a huge part in the development of reason and understanding. It gave us two bright heavenly bodies to which we could observe and know were always there never changing yet, they acted in predicable ways and confounded and astonished us when they changed their usual patterns. As in how a person tends to act in unpredictable ways because of their experience which developed personality. Through the process of learning to communicate those concepts language and art came into being. But it began when we looked up and wondered about our world and our place in it .
This could have been why the Sun and the Moon were worshiped as deities in most of the early primitive societies. Through droughts, through monsoons, through plagues, and disease, through years of splendor and of plenty.The Sun and the Moon have always been in the heavens acting like cosmic Mother and Father watching over us on Earth. They scared us when they crossed paths like a mother a father fighting in the sky as their children below sank in fear. Darkness surrounded them and for a moment it seemed like night would rest over our world for the rest of time and the long sleep would take us into eternal darkness. These contemplative thoughts are the exact reason why I believe the Moon and the Sun played a big part in our being human and beings of reasoning. So much so we reached up so that we visited our Moon."
The Jovian Giants of the Deep
We now move on past Mars and the Asteroid Belt on to Jupiter. Out here in the realm of giants we are now far enough from our Sun that we need to bundle up as the temperature drops dramatically here. Out here we enter the little understand Jovian kingdom and Jupiter is it's lord. This massive world is bigger than all the planets, asteroids, and moons in the Solar System put together. It protects us from rogue comets and large asteroids and if I were an alien visitor to the Solar System I'd probably identify our Solar System as having one star and a large gas world with some solar debris left over. So lets bundle up and visit these titans of the deep!
The Outer Solar System
The Jovian Worlds (Gas Giants) and the Ice Titans (Ice Moon and Kuiper Object Systems):
Jupiter 5th planet from the Sun:
When you think of Jupiter you have to think BIG. Jupiter is the largest planet in the solar system. It is a gas world banded in colorful clouds which storm over the entire face of the planet. Lightening strikes flash upon it's dark side. Jupiter's atmosphere is also home to the largest storm in the Solar System. The Great Red Spot as it is known for its color and size would fit three Earths inside its oval. The spot has been observed for over 300 years and has gone through periods of low activity and then come back to full strength over time. The cloud bands on Jupiter seem to act like gas conveyor belts where pressure systems drive jet streams gaseous materials to different altitudes. This gives rise to the distinctive bands we see circling inside Jupiter's super dense atmosphere. As the layers decrease in altitude the pressures build and the gas becomes more and more dense. A 3 mile an hour wind on Jupiter would knock over a house as it's density would be so thick as to act like a solid against the mass of the house.
Saturn the 6th planet from the Sun:
Saturn has always called out for us to look up in awe and wonder. It's disc was just so different then all the other lights in the heavens. And when we were able to view Saturn through telescopes we gazed upon an alien world not dreamed of by men. It's ever changing disc proved to be a system of planetary rings. Soon Saturn's moons were viewed as well. Even to this day Saturn is changing the way we view the Solar System. The planet's dynamic ring system is composed of clumps of ice and dust the size of micrometers to meters in breadth. Two of Saturn's moons orbit Saturn within the ring system. Saturn is a gas giant like Jupiter but still smaller than its huge neighbor. Saturn is a very lite world in that if you could construct an ocean large enough to throw Saturn into, like a beach ball it would float on top. It is an airy world full of mystery and only now with the Cassini spacecraft are we learning about this amazing world with all its dynamic winds and bands and many moons.
Uranus the 7th planet from the Sun:
Uranus is the third largest world in our Solar System. It is visible to the naked eye but was not recognized as a planet until 1781 when Sir William Herschel announced that he had discovered Uranus. It was the first planet ever discovered with a telescope. Uranus is a gas giant like its cousins Jupiter and Saturn which share many similarities but in Uranus's case it is considered a much colder world compared to Jupiter and Saturn which are mostly composed of hydrogen and helium like our Sun. Uranus and Neptune the next planet on the list are ice giants/ These worlds contain more water, ammonia and methane with traces of hydrocarbons. Uranus happens to have the coldest atmosphere in the Solar System at -224 degrees. It has a complex layered cloud system with water clouds at its lowest levels. The interior is thought to be made of ice and rock. Uranus has a ring system but it is small compared to Saturn's and it is host to many moons. Uranus also has a magnetosphere like Earth. Uranus rotates on its side.and planetary astronomers believe this could have been caused by an ancient impact to the planet.
Neptune the 8th planet from the Sun:
Neptune named for the Roman god of the sea. Neptune like Uranus is composed of hydrogen and helium it has many of the same gasses as Uranus such as ammonia, methane, and water in gas form. It is the farthest planet from the Sun and is a near twin for Uranus. It was discovered using a gravitational perturbation. Johann Galle discovered Neptune. Much of Neptune's blue appearance is because of the high amounts of methane in its upper atmosphere.
The Kuiper Belt is an area outside the main orbit of the planets (though they do cross orbits with Neptune and Triton Neptune's largest moon is believed to be a captured Kuiper Belt object). It consists of dwarf planets or small bodies which are composed of much of the same gasses we see in comets such as ice, ammonia, and methane. These ice worlds have eccentric orbits like the Pluto Charon system that can cross Neptune's regular orbit around the Sun. It is believed that the formation of Neptune gravitationally upset these minor bodies and sent them into long scattered orbits even as far as up to a 100 AU's away from the Sun and at odd angular orbits. Unlike the comets though they have a more stable existence in the far reaches of the Solar System. They are also called trans-Neptunian obhects.
The Oort Cloud:
The Oort Cloud is home to billions of small ice bodies which make up many of the rare comets that fall into the Inner Solar System making for spectacular, orbit far away from the Sun. These vagabonds of the Outer Solar System spend their time in perpetual darkness; stuck in deep darkness between our Sun and it's nearest neighbors. It is thought that as stars form, their excretion disk or debris cloud surrounds the Planetary disk. Out in this place between 1k and 3k AU the solar system we are that the very edge of the Solar System. These comets will sometimes experience a wobble in the gravitational field or influence from the interstellar medium and be perturbed just enough to make a one time trip through the Solar System and light up like a firework. Most of the time these comets dive straight into the Sun but some survive to swing back out into the darkness of deep space.
The Great Beyond!
Out here beyond the solar system in the stygian deep between the stars even light at a 186.000 mps takes years to reach even our closest neighboring star. Storms of interstellar dust and gas flood the medium and temperatures are extremely low. This is the vast ocean or rift between our Sun and it's closes neighbors. This dark and lonely void beckons us to turn back home to the comforts of our Star's warmth but out beyond the rift are other solar systems to be discovered.
Where We Are In Our Milky Way Galaxy
Our Local Star Systems
B: The Sun's Neighborhood:
Astronomers classify our sun as an ordinary yellow star. Distances are shown in light years or how far light travels in one year of travel at the speed of light. It takes the light from the sun 8 minutes to reach us here on the ground. The sun's light is 93.2 million miles away. Light travels at a 186,000 miles per second. The Sun's light does not touch Pluto for another 5 hours and not for 4 years and 4 months does it reach our closest stellar neighbor Alpha Centauri. Alpha Centauri is a multiple star system made up of 3 stars locked in a gravitational dance as they orbit each other.
Where We Are Compared to Nearby Galaxies (The Local Group)
C:The Local Group:
Our Milky Way galaxy is located within a cluster of some 20 galaxies called the Local Group. The Milky Way, (a spiral bar galaxy), it's sister Andromeda (M31), and smaller M33 are all spirals which spin at a fast rate. The Andromeda galaxy is filled with star clusters and dust clouds. NGC 205 is an elliptical galaxy made up of ancient stars. The Large and Small Megellanic Clouds are called irregular galaxies; they have been described as a haze by the Magellan's crew in 1520. These galaxies all move in random paths and are glued together by gravity.
Super Clusters The Larger Structures of the Universe
The Virgo Super-Cluster
D. Local Supercluster:
Like schools of fish they congregate in supoerclusters. Virgo is the largest and is the closest to our Local Group, it is 50 million light years away in the middle of our supercluster. It is rich in thousands of member galaxies.
There is new surfacing observations that show great voids of empty space between the superclusters. This has astronomers saying the universe has a sort of sponge like quality to its larger over all structure. These galactic super clusters connect through stellar filaments that stretch between giant voids.
How Big is the Universe?
Universal Reference Map
Back to Where We Started
We are heading back now... We move through the soup that was the beginning of our Universe, the super heated plasma that once permeated everything so many billions of years ago. We fly past the super clusters and the great spacial divides between the galaxies, back into our galactic neighborhood The Local Group. We slip past Andromeda and towards our own galaxy the Milky Way. There in the arm of Orion Cygnus, on the inner edge is our solar neighborhood. There we see the closest stars to our Sun, we pass Sirius the Dog Star and then Alpha Centauri. Soon we are entering the Oort Cloud passing frozen debris from the formation of our Solar System. We glide pass the Kuiper Objects and then we see the familiar blue of Neptune. We head passed Uranus, then Saturn and Jupiter. We are now navigating the Asteroid Belt and soon we come to Mars. We cross the divide from Mars to Earth and we feel the warmth of our life giving Sun as we touch back down on Earth. We have traveled backwards in time and now come full circle back to the present. We know where we are now, back home on Earth.
Thanks for taking the journey with me, I hope you learned something. I know I did.