Astronomy 101, page 1

I have decided to make this thread to inform all who might not know to much about outer space and thus may be confused when reading the majority of the threads here on ATS.I think it goes without saying a basic level of understanding of astronomy is needed on ATS since we mainly deal with "space aliens" and UFOs(which fly in space,lol).Also I think it is a basic human need to at the very least understand the fundamentals of Astronomy,our very closest outer space around our planet.Do you realize most can not name all of the planets in OUR solar system,let alone in order of distance.Yet we want to talk about planets that "Greys" or "Pleiadians"come from,or Nibiru(planet x).It is important to have a understanding of the vast distances in space as well as the multiple "out of this world" phenomena we find there.We find a lot of times members speaking of multiple astronomical terms when conversing about the various topics on ATS(mainly UFOs and aliens),so I figured this would help some of the less informed members and visitors to this site.It is necessary to have solid fundamentals in well,science,especially when we try to be scientific and use that process.I also think that space is the next 'big issue' in our 21st century society and because of that it is important to be informed on the aspects of space.I will present this introduction to Astronomy in multiple chapters explaining different basic things from GRB's to Astronomical Units to Planetary distances.Notice I will just briefly touch on the "Big Bang" and other cosmological related topics as they are still highly disputed.Well here we go and I hope this helps.


Outline of Chapters
Preface:A Short History of Astronomy
1.The Formation of the Universe,Galaxy,and Solar System
2.Some Basic Distance,Speed,and Measurement Terms
3.Our Solar System
4.Our Interstellar Neighborhood
5.Some Strange Things in Space



A short history of astronomy

Astronomy is the scientific study of celestial objects,dating back to Mesopotamia,Egypt,Greece,Rome,etc astronomy has been a way for us to explore our curiosity of that greatness we always look upon at night an wonder "What is that and why are they there?".Early on in civilization all we had was the naked eye and a high point to observe the heavens with(you can now imagine why they thought some of the "crazy" stuff they thought then about Earth and space).Objects like Stonehenge were used to calculate the cycle of the Sun and moon and thus was used as a calender.Also positions of the visible planets and stars were mapped.It was not until around 1608 did astronomy take its next big step when the first telescope was invented(now many people think it was Galileo but it wasn't)by Hans Lippershey,a Dutch eyeglass maker who created it for military use.Of course the great Galileo took this invention and made it better and by 1609 was using it to observe the night sky.

While Galileo Galilei did not invent the telescope, he made great improvements in the technology. His first construction was a three power instrument, which he quickly improved to eight, twenty and then thirty power. With this new tool, he found mountains and craters on the moon, discovered that the Milky Way was composed of stars, and discovered the four largest moons of Jupiter.

space.about.com
While Galileo is commonly considered the father of both astronomy and modern science he was proceeded by great scientist which he built is knowledge off of their observations.Johannes Kepler ,Sir Issac Newton,and Nicolaus Copernicus to name a few.We can thank all of them for our current knowledge of the Earth revolving around the Sun(Heliocentric),elliptical orbits,gravity,etc.Fast forward a few hundred years and through some great astronomers like Edwin Hubble and we have telescopes so powerful that if you looked at two fireflies in Japan from New York you could see them both clearly and distinctly.Or so powerful we can see stars over 2billion light years away!I am referring to the Hubble space telescope of course,but that is not it as we have X-ray telescopes,Infrared,Radio,Ultraviolet,Gamma ray,Gravity wave,Neutrino-the list grows ever on.So through our science,physics,math,and pure human observation we have gone from looking up blindly at the sky at night to launching telescopes into orbit,sending men to the Moon,and looking to the deepest recesses of the Universe.

1.The Formation of the Universe,Galaxy,and Solar System
The "Big Bang" is the generally accepted cause for the creation of our universe.Simply put the Big Bang was an explosion of a singularity(a point where finite matter is squashed into a infinite density) that contained all the matter and energy(some believe infinite matter and energy) of our universe an estimated 13.7 billion years ago.Apparently we reside inside this singularity and this is what our universe is.So now lets go from 13.7 billion years ago to about 8 or 9 and galaxies,including ours-the Milky Way formed as the Universe cooled down and molecules formed together to form stars and stars pulled other stars and dust in and so on until a galaxy is formed(this is called accretion).We live in what is called a Barred Spiral Galaxy because it is shaped similar to a an elongated pinwheel.Now lets fast forward to about 4.5 billion years ago,our Sun has formed likely due to a shockwave from a supernova,as well our solar system due to the same accretion(the pulling together of matter due to gravity) that formed the galaxies.At this point our planet is in its primordial stages(4.5 billion years ago) as is the rest of the solar system,over time it became what we know it today as.Here is a picture of the solar system to help:

aerospaceweb.org
Here is a picture of the core of the Milky Way in Infrared

wikipedia.org
It is currently impossible to view our galaxy as a whole because we can not travel out side of it to take a picture,but we can see others like ours.Our galaxy has a diameter of 100,000 lightyears-a thickness of 1,000 lightyears and contains an estimated 200-400 billion stars.(And we are the only life form???)Our galaxy has a North and South Galactic Pole and our sun rotates around the center every 220 million years(can you see how in space the aspect of time is immense).Our galaxy has 4 major arms in its spiral,they are(In order of closest to galactic center on out);Norma,Scutum-Crux,Sagittarius,Orion,Perseus,and Cygnus.Here is a link to a mapthat illustrates these.About half way between the rim and center lies the Orion arm and in the Orion arm lays our home,our solar system.Our galaxy,like other spirals has 5 distinct parts;The flat,rotating disc...a central bulge(where the arms disappear)...the "Halo",which is the spread out stars around the perimeter of our galaxy...and the galactic core(which contains a supermassive black hole,as all galaxies are thought to).Together with Irregular galaxies,spirals make up 60% of the galaxies in the visible universe.
Here is a picture of the Pinwheel Galaxy,which looks similar to ours

wikipedia.org
2.Some Basic Distance,Speed,and Measurement Terms
*Lightyear(ly)-The distance it takes light to travel in one year.
*Lightspeed-186,000 miles per second
*Astronomical Unit(AU)-One unit equals the mean distance from the Earth to the Sun(93,000,000 miles).
*Lightsecond,minute,hour,etc-Time it takes light to travel per unit of specified time.
*Parsec-One parsec(The parallax of one arc second) equals 3.259 lightyears and is used in astronomy for location and distance purposes.
*Parallax-The apparent displacement of an object when viewed along two different lines of sight.Used to determine close and near stars.
*Precession-The 'wobble' of a planetary body on its axis due to gravitational pull.This is also responsible for the change in seasons.
*Clestrial Sphere-The total area of the sky visible at anytime from any point on Earth.
*Zodiac-The twelve constellations that cross the ecliptic each year.
*Ecliptic-The apparent path that the sun traces out in the sky every year.
*Constellation-A group of stars in the sky that appear to form a pattern.There are 88 of them.
*Vacuum-Volume of space that is essentially empty of matter and pressurized gases(atmosphere).
*Arc-Unit of angular measurement equal to 1/160 of one degree.
*Right Ascension-RA is the astronomical term for one of the two coordinates of a point on the celestial sphere when using the equatorial coordinate system. The other coordinate is the declination
*Distance in miles and AU's of one lightyear-63,241 AU's and about 6,000,000,000,000 miles.
*Diameter of solar system-Between 100-300,000 AU's.
*Distance to exit solar system-Best guess anywhere over 10,000 AU's.
*Deep Space-Used when referring to anything between star systems or galaxies generally.Although it is sometimes used when speaking of anything outside Earths orbit.
*Satellite-A natural moon.
Continued.........




[edit on 4/10/2009 by jkrog08]



[edit on 16-5-2009 by spacedoubt]

*Black Hole-A point in space created by a supermassive star collapsing in on itself due to its massive gravity that 'sucks in' everything,even light into a singularity.
*Supermassive Black Hole-A very large black hole that is at least 5 solar masses in mass.
Note:The following events take place well beyond the orbit of our most distant planet,Neptune.
*Termination Shock-The termination shock is the point in the heliosphere where the solar wind slows down to subsonic speed (with respect to the star) due to interactions with the local interstellar medium.
*Bow Shock-The point where the interstellar medium, travelling in the opposite direction, slows down as it collides with the heliosphere.
*Heliosphere-A 'bubble' like surrounding our solar system from all our solar gases blown from the solar wind(which can travel over a million km per hour).
*Heliopause-The point where the interstellar medium and heliosphere pressure is balanced out.
*Interstellar Medium-The majority of interstellar space that consists mainly of Hydrogen and Helium from our galaxy.
*Heliosheath-The heliosheath is the region of the heliosphere beyond the termination shock. Here the wind is slowed, compressed and made turbulent by its interaction with the interstellar medium. Its distance from the Sun is approximately 80 to 100 AU's at its closest point.The heliosheath is shaped like the coma of a comet, and trails several times that distance in the direction opposite to the Sun's path through space. At its windward side, its thickness is estimated to be between 10 and 100 AU The current mission of the "Voyager 1" and "Voyager 2" space probes includes studying the heliosheath.

wikipedia.org
*Nova,Supernova,and Hypernova-Exploding stars at the end of their life cycle,the terms "super and hyper" simply refer to their intensity.
*Dwarf Stars-Small sized stars,either early in life cycle or at very end.
*Giant Stars and Super Giant Stars-Massive stars at the end of their respective life cycle who's enormous size is attributed to their rapid consumption of Helium.
*Main Sequence Stars-Stars in the "prime" of their life cycle,like our sun.
*Gas Giants-Planets large in size with no solid ground.
*Terrestrial Planets-Planets small to medium in size comprised of a rocky surface.
*Nebula-Collections of interstellar cloud and dust,where stars are born.
M-16 Nebula

aspire.cosmic-ray.org
*Average temperature of space-2.275 Kelven(-455 F),three degrees shy of absolute zero.
*Shape of universe-Believed to be either flat or spherical,but infinite.
*Types of galaxies-Elliptical,Irregular,Spiral,Barred.There are several sub-types for each,the names describe themselves.Also there are two other kinds that emit different spectres more than others;Radio(highly radio) and Quasars(highly energetic).

Now let us talk about our solar system,home of our sun, eight planets, and many "outer rim" planetoids such as Pluto and Eris.
3.Our Solar System
The Sun
Our star,which we call The Sun is a Yellow Dwarf(an average star) which is at the center of our solar system.Our sun accounts for 98.6% of our solar systems mass and made up mostly of Hydrogen and Helium as well as various other elements.It is about 93,000,000 miles from Earth, has a mean diameter of 109 Earths,and a mass of 332,946 Earths.It releases energy on the scale of 4.26 million metric tons per secondand is made up of nine distinct parts from the Corona to the core.It is a near perfect circle and is the source for most life on Earth.It has an apparent rotation of 28 days at its equator,although it has what is called a differential rotation because it rotates faster at its equator than at its poles,this is because it exists in a Plasmatic(the fourth state of matter).


wikipedia.org
Now for the planets in order of distance from Sun.
The Terrestrial Planets(planets with a solid surface)
*Mercury

wikipedia.org
Mercury is the innermost and smallest planet in the solar system orbiting once every 88 days.It has trace atmospheric pressure and the mass of 0.055 Earths as well as a surface area equal to 0.108 Earths.It has no moons and its surface temperatures range from -297 to 801 degrees F.At its closest point in orbit Mercury is 57,000,000 miles from Earth.
*Venus

factmonster.com
Venus is the second planet out from the Sun and also has no moons.Venus also has a peculiar retrograde axial rotation(it rotates backwards compared to the other planets) believed to have been caused by a massive meteor or comet impact in the past.Venus is sometimes called the Earths twin because they are similar in size with Venus being 650 miles less in diameter than the Earth.Venus has what scientist call a "runaway greenhouse effect" probably from rapidly evaporating oceans in its far past.It has a very thick atmosphere that contains 95% Carbon Dioxide which rains sulfuric acid under the crushing pressure and temperatures of up to 900 degrees F.Its surface is rocky with multiple volcanoes,mountains,canyons, with a 200 mile long river of hardened lava.It takes 225 Earth days to orbit the Sun.
*Earth

researchpark.arc.nasa.gov
We won't spend to much time on this planet as I think we all know quite a bit about it.Earth is on AU from the sun and appears like a swirl of white and blue from space.It has one moon called(lol)the Moon or Luna.It is the only known planet with life and liquid water.It is in between the smallest and largest of the planets in the solar system.It has a circumference of about 25,000 miles and a diameter of 7,926.41 miles.
*Mars

factmonster.com
Also known as the "Red Planet' because its rusty red color(due to high Iron content) Mars has 2 moons(Phobos and Deimos) and is about half the size of Earth.It is the fourth planet out from the Sun and the last of the terrestrial planets.The temperature averages about -80 F as Mars lacks a strong atmosphere like Earth.Mars has the highest mountain in the solar system in Olympus Mons and likely has frozen water in its permafrost and ice caps at its poles.Carbon Dioxide makes up 95% of its atmosphere.Mars is reminiscent of a "wasteland desert" as it is barren with scattered mountains,canyons,and valleys subject to intense dust storms.At the closest point in its orbit Mars is 35,000,000 miles from Earth.
*Asteroid Belt

The asteroid belt is the region of the Solar System located roughly between the orbits of the planets Mars and Jupiter. It is occupied by numerous irregularly shaped bodies called asteroids or minor planets. The asteroid belt region is also termed the main belt to distinguish it from other concentrations of minor planets within the Solar System, such as the Kuiper belt and scattered disc.
More than half the mass of the main belt is contained in the four largest objects: Ceres, 4 Vesta, 2 Pallas, and 10 Hygiea. All of these have mean diameters of more than 400 km, while Ceres, the main belt's only dwarf planet, is about 950 km in diameter.

wikipedia.org
The Jovian Planets(planets with no solid surface,Gas Giants)
*Jupiter

factmonster.com
Jupiter is the largest planet in the solar system and possibly a failed star(Brown Dwarf).About 1300 Earths would fit into Jupiter and its diameter is 88,736 miles.It has the "Great Red Spot"which is a hurricane type storm greater in size than the Earth which has been going on for centuries.Its multi-layered atmosphere is made up of dust,methane,ammonia,hydrogen,helium,water,and other elements.Its average temperature is -234 F and it has no surface,just layer after layer of gas and further down liquid forms of the gases(due to the pressure).Jupiter has the most moons of any planet in the solar system with 63 known and 4 rings.At its closest it is 371 million miles from Earth.It takes twelve years to orbit the Sun and,like all Jovian planets has a rapid axial rotation as its days are only around 12 hours long.
Continued


[edit on 4/10/2009 by jkrog08]


[edit on 16-5-2009 by spacedoubt]

*Saturn

factmonster.com
"Lord of the Rings",Saturn is probably the most famous planet because of its massive rings,which actually are only 20 meters in thickness!Also because of the large amount of buoyant gases on Saturn if you could find an ocean big enough to throw it into it would float!Saturn is about ten times in diameter than Earth and has an atmosphere made mostly of Hydrogen and Helium with an average temperature of -288 F.A day is ten hours and a year is 29.5 Earth years.At its closest Saturn is 733 million miles from Earth and has 31 known satellites and over a thousand rings made up of ice particles.Again,like Jupiter Saturn has no surface.
*Uranus

www.factmonster.com...
Uranus is the seventh planet out and twice as far from the Sun as Saturn.It wasn't discovered until 1781 by William Herschel.It is four times the diameter of the Earth.Little is known about its surface but it is believed to be similar to the other Jovian planets,its atmosphere contains Hydrogen,Helium,and Methane.It has a uniform temperature of -353 F.It rotates on its axis once ever 17 hours(as with all non Earth objects hours is in "Earth hours") and orbits the Sun every 84 Earth years.At Uranus's closest point it is 1.6 billion miles from Earth.It has 27 moons and eleven rings.
*Neptune

factmonster.com
We now come to the last planet in our solar system,the stormy blue planet named after the Roman god of the sea and that is thirty times further from the Sun than Earth.It is 4 times the diameter of Earth and has a gaseous and liquid "surface" made up of methane,ammonia,hydrogen,and helium and has constant raging storms like the "Great Blue Spot".The average temperature is - 353 F and it rotates every 17 hours and orbits every 165 years.It is 2.6 billion miles from Earth at its closest point.It has 13 moons and four rings and has its magnetic poles 'sideways',on the horizontal axis.
*The Planetoids
Pluto,Eris,and other "Dwarf Planets"(Trans-Neptune Objects,Plutoids,etc) make up the rest of the planetary bodies in our solar system.They do not meet the criteria to be classified as planets but are larger than asteroids.In fact Pluto was once a planet and then reclassified after the discovery of Eris,which was larger than Pluto!So the mythical planet "X" does in fact exist as many small planetoids out beyond the orbit of Neptune,but before the Orrt Cloud.The picture below is a picture of Eris and its moon taken by the Hubble.

wikipedia.org
After these planetoids we have the Kelper Belt(another,much larger asteroid belt extending from 30-55 AU out),the "shock zones" of the Heliosphere I talked about earlier(55-100 AU)and the hypothetical lightyear distant Oort Cloud(which is 50,000 AU away,nearly a quarter of the 200,000 AU distance to Proxima Centauri),which is a cloud of orbiting comets on the outer edges of our system.AND THEN we are out of our star system with 4.2 lightyears to go to Proxima Centauri.
4.Our Interstellar Neighborhood
Proxima Centauri(In X-Ray)

wikipedia.org
At 4.2 Lightyears from Earth Proxima Centauri is our closest star(about 200,000 AU's or 24 trillion miles).The distances in space are immense as an understatement our "local group" of stars are all stars within a 500 lightyear radius of the Sun.Going out in terms of distance from Earth are:
*Rigel Kentauris(A and B) at 4.3 ly
*Barnards Star at 6 ly
*Wolf 359 CN at 7.7 AND Wolf 359 BD at 8.2 ly
*Sirius at 8.5 ly
*Epsilon at 10.8 ly
*Procyon A at 11.4 ly
*GJ 682 at 16.3
*****And for all you Grey fans out there......The Zeta Reticuli system is 39.5 ly away.

Here is a few pics of the Pleiades star cluster(440 lightyears away)

Another.....

That one was of the Reflection Nebula around the cluster
wikipedia.org
Sirius.....

space.about.com
The Hubble Deep Field view containing some of the furthest pictures ever taken of our universe.Mostly you see galaxies,you can see some stars(mostly in the foreground)......Here's more:

January 15, 1996: One peek into a small part of the sky, one giant leap back in time. The Hubble telescope has provided mankind's deepest, most detailed visible view of the universe.
Representing a narrow "keyhole" view stretching to the visible horizon of the universe, the Hubble Deep Field image covers a speck of the sky only about the width of a dime 75 feet away. Though the field is a very small sample of the heavens, it is considered representative of the typical distribution of galaxies in space, because the universe, statistically, looks largely the same in all directions. Gazing into this small field, Hubble uncovered a bewildering assortment of at least 1,500galaxies at various stages of evolution.

hubblesite.org


Some of these objects in the Deep Field are 12 billion light years away,truly astounding.You look at just that small number of galaxies and think "wow,the possibilities"(at least I do,lol).
5.Some Strange Things in Space
I know this thread is pretty long(it has gone further then I wanted it to,but it does contain a lot of info)so I will just show you this Universe episode on the strangest things in space and then close with a brief explanation on gamma ray bursts.It is really good and covers the coolest things(and most important).So I hope you enjoy!
Part One

youtube.com

The Universe is a great show isn't it?I love it,we watched it in my astronomy 101 class last year quite a bit.Props to the History Channel for airing it.Alcohol clouds,dark matter,pulsars,magnetars,pulsar planets,neutrinos,etc......Oh my!lol

Gamma Ray Burst
GRB for short, a gamma ray burst is the most powerful event in the Universe since the Big Bang.Originally picked up in the 60's by an American spy satellite designed to monitor Soviet nuclear tests they were originally thought to be alien battles in deep space!We quickly found out that is not true as they are super luminous explosions from collapsing super dense stars like pulsars,magnetars,neutron stars,and black holes.They emit a super high level of gamma radiation and are observed as brilliant flashes of light that overwhelm any other light source in the cosmos.They typically last a few milliseconds but can last minutes.The only ones detected have been over 1000 ly away.It has been postulated that a GRB caused the Permian Extinction(K-T Boundary layer) in which 99 % of life was killed off some hundreds of millions of years ago.If one were to 'go off' say 500 light years or closer and was aimed in our direction it would be catastrophic and an "Extinction Level Event".NASA currently has orbiting telescopes,like the "SWIFT" monitoring these events and typically sees about three per week in deep space.Here is a picture of the "afterglow" of one from 1999........

wikipedia.org

Conclusion

One thing I learned in my formal astronomy class was that you ask a lot of questions but the truth is for a lot of things you think we know,we really don't!Astronomers don't know near as much as you would think,so sometimes you get disappointed when looking for facts on something there isn't.Like I said earlier I think astronomy is a 'core requirement" for todays life,and definitely here on ATS!I hope I educated some people and I hope you all liked what I put on here.Like I said I hope it wasn't to long but it will greatly help you understand more of our immediate vicinity outside our wonderful planet Earth.So again,hope you liked it and found it educational or entertaining as that was its purpose.Well hopefully now you understand more than before about astronomy and the wonders of the universe.






jb.man.ac.uk

*******
big-bang-theory.com
space.about.com
factmonster.com
nbdc.noaa.gov
windows.ucar.edu
space.com
wisegeek.com
aspire.cosmic-ray.org

[edit on 4/10/2009 by jkrog08]

reply to post by fishneedh2o

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He has mentioned pluto under the planetoids category, which is the category it is supposed to be, under the decision of the IAU.

[edit on April 10th, 2009 by peacejet]

reply to post by AntiConspirator

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The "X" is not a Roman numeral but the letter "X", as in unknown.

reply to post by ngchunter

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Ha,good point on the mechanics thread ,though I am going to have to take a break as this thread took about a day to do(longest I've spent).But your right we do need more 'explanatory threads'.Internos does a good job on them and has quite a few.I am glad you liked it!

Not a problem,thats what I wanted.You might like this as well:www.abovetopsecret.com...'

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