Astronomy paste-up

(Basic)

INDEX
horizon
equator
ecliptic
earth's orbit
 
 

F O L

moon
moonspath
 
planets
precession
conjunction

http://employees.oneonta.edu/farberas/arth/Images/109images/4thc_hellenistic/aph_knidos_det.jpg

 
 

 

 

 

the Horizon - depends where you are on the Earth - the Zenith - ditto - it is the point directly overhead , wherever you are

the Celestial Equator - a projection of the Earths equator up into the sky   ..the North and South Celestial Pole , ditto

the Ecliptic - the plane of the Earth's orbit around the sun - or the path the sun makes in the sky , depending on how you look at it .The Ecliptic and the Celestial Equator would be the same if the Earth was not tilted on its axis - but it is ( which is why we have different seasons ) - and they are not - by 23 and half degrees

the Ecliptic and the Celestial Equator cross at two points , the Spring and Autumn Equinoces

All the planets and the moon have eliptical orbits but they are all more or less in the same flat plane with the sun ( except Pluto which is more wayward ) - so that viewed form Earth , they all take roughly the same path through the sky ( the Ecliptic ) and this path is divided up into twelve sections called the Zodiac afer the costellations on it which are mainly animals

except Libra - Virgo ...Gemini ..... Aquarius isnt really an Animal either .. the Zodiac is what its still called .....

the moon orbits the Earth so relates to the Earth as it circles the Celestial Equator  - so the path of the Moon is close to the Ecliptic but crisscrosses it twice a month

 

Horizon and Equator

Note that the daily rotation of the Earth causes each star and planet to make a daily circular path around the north celestial pole referred to as the diurnal motion.

HERE

http://abyss.uoregon.edu/~js/ast122/lectures/lec02.html  

HERE

 

 

Celestial globe -

 

Fig 1: Celestial Globes are useful tools for teaching astronomy coordinate systems so they are often found in astronomy lab classes. Other websites that explain the celestial sphere:

image of celestial globe that can be used in a classroom

1.   Using RA and dec

All stars and other objects in the sky are at different distances from earth. But if we for a moment forgot that and instead imagined them on the inside of a great sphere surrounding the earth then we'd have something called a celestial sphere. Now what if we wanted to describe the positions of those stars and objects? Since the celestial sphere surrounds the earth, let's do a few things. First, extend the earth's equator out until it intersects the celestial sphere. Now we have the celestial equator. Do the same thing with the earth's poles and we have the celestial poles. On earth, we can measure latitude as how far north or south something is from the equator. If you are at the equator you are at 0° latitude. At the North Pole, you are at +90°. So latitude is measured from 0 to ±90°. We can do the same thing on the celestial sphere, but instead we call it declination. Declination is also measured from 0° at the celestial equator to ±90° at the celestial poles.

A little tougher to translate is longitude. On earth we define it as how far east or west a place is from the Prime Meridian which is defined as a line beginning at the North pole, passing through Greenwich, England (UK), then ending at the South pole. There are historical reasons for that. But what about in the sky? Is there a 'Prime Meridian' up there? Yes, there is but first we need to define some other points in the sky.

Visualize the earth with the celestial sphere surrounding it and the celestial equator and poles are marked. Now, I bet you're imagining this with the earth's axis perfectly vertical. Remember, the earth's axis is tilted in relation to its orbit. So now it's tougher to imagine, but running across our celestial sphere is another line called the ecliptic.

One way of 'seeing' this line is to imagine the earth and celestial sphere going around the sun as one unit. As the earth moves around the sun, the sun is moving across the celestial sphere. When the earth is tilted away from the sun (northern hemisphere winter), then the sun and ecliptic are below the celestial equator. When the earth is tilted towards the sun (northern hemisphere summer), the sun and ecliptic are above the celestial equator.

graphic showing intersection of the celestial equator and ecliptic
Fig 2: Simple graphic showing the celestial equator, celestial poles and ecliptic.

 And then there are those two times when the axis is not tilted towards or away from the sun (spring and fall) so it looks like the sun and ecliptic are crossing the celestial equator. The winter and summer points are called the solstices and the spring and fall points are called the equinoxes. Because springtime is a time of birth and renewal, the Spring or Vernal equinox was considered to be very important so it was natural that when astronomers were trying to figure out a 'Prime Meridian' for the sky that they would choose a meridian passing through the Vernal Equinox. Because the vernal equinox is the point in the sky where the ecliptic crosses the celestial equator from south to north or is ascending, we call these longitude-like lines 'lines of RA or right ascension.'

So now we know where the 0 point or prime meridian is in the sky. How do we measure RA in the sky? Remember, on earth we measure longitude east and west from the Prime Meridian. In the sky, we measure it slightly differently. Earth is slowly turning on its axis -- once every 24 hours. Let's say that one day the Vernal equinox is crossing our local meridian (the line running north-south through the zenith, separates the sky into east and west). An hour later, we can imagine that crossing our meridian is another line of RA. And every hour after that, we have another line of RA overhead until we're back where we started. So we number these lines of right ascension in hours from 0 to 24.

http://dawn-aop.astro.umd.edu/intermediate/sec1.shtml

 

Ecliptic

Since the Earth's axis is tilted 23 1/2 degrees from the plane of our orbit around the Sun, The apparent motion of the Sun through the sky during the year is a circle that is inclined 23 1/2 degrees from the celestial equator. This circle is called the ecliptic and passes through 12 of the 88 constellations that we call the zodiac

 

tilt of Earth's rotation axis Since the ecliptic is tilted 23.5 degrees with respect to the celestial equator, the Sun's maximum angular distance from the celestial equator is 23.5 degrees. This happens at the solstices. For observers in the northern hemisphere, the farthest northern point above the celestial equator is the summer solstice, and the farthest southern point is the winter solstice. The word ``solstice'' means ``sun standing still'' because the Sun stops moving northward or southward at those points on the ecliptic. The Sun reaches winter solstice around December 21 and you see the least part of its diurnal path all year---this is the day of the least amount of daylight and marks the beginning of the season of winter for the northern hemisphere. On that day the Sun rises at its furthest south position in the southeast, follows its lowest arc south of the celestial equator, and sets at its furthest south position in the southwest. The Sun reaches the summer solstice around June 21 and you see the greatest part of its diurnal path above the horizon all year---this is the day of the most amount of daylight and marks the beginning of the season of summer for the northern hemisphere. On that day the Sun rises at its furthest north position in the northeast, follows its highest arc north of the celestial equator, and sets at its furthest north position in the northwest. The seasons are opposite for the southern hemisphere (eg., it is summer in the southern hemisphere when it is winter in the northern hemisphere). The Sun does not get high up above the horizon on the winter solstice. The Sun's rays hit the ground at a shallow angle at mid-day so the shadows are long. On the summer solstice the mid-day shadows are much shorter because the Sun is much higher above the horizon.

http://www.astronomynotes.com/nakedeye/s5.htm

 

The Sun appears to drift eastward with respect to the stars (or lag behind the stars) over a year's time. It makes one full circuit of 360 degrees in 365.24 days (very close to 1 degree or twice its diameter per day). This drift eastward is now known to be caused by the motion of the Earth around the Sun in its orbit.

 

The apparent yearly path of the Sun through the stars is called the ecliptic. This circular path is tilted 23.5 degrees with respect to the celestial equator because the Earth's rotation axis is tilted by 23.5 degrees with respect to its orbital plane. Be sure to keep distinct in your mind the difference between the slow drift of the Sun along the ecliptic during the year and the fast motion of the rising and setting Sun during a day.

 

 

http://www.astronomynotes.com/nakedeye/s5.htm

Sun motion among zodiac constellations

Sun motion among zodiac constellations

 

Earths eliptical orbit

 

discussed HERE

earth orbit around sun

 

see captionJanuary 4, 2001 -- This morning at 5 o'clock Eastern Standard time (0900 UT) Earth made its annual closest approach to the Sun -- an event astronomers call perihelion. Northerners shouldn't expect any relief from the cold, however. Although sunlight falling on Earth will be slightly more intense today than it is in July, winter will continue unabated.

"Seasonal weather patterns are shaped primarily by the 23.5-degree tilt of our planet's spin axis, not by Earth's elliptical orbit," explains George Lebo, a professor of astronomy at the University of Florida. "During northern winter the north pole is tilted away from the Sun. Days are short and that makes it cold. The fact that we're a little closer to the Sun in January doesn't make much difference. It's still chilly -- even here in Florida!"

more at NASA site  - HERE

see captionMost planets follow orbits that are more elliptical than Earth's. Pluto's orbit,

Above: The orbits of Mercury (red), Earth (blue) and Mars (black). The solid lines indicate each planet's elliptical path around the Sun. The dotted lines show circular paths with the same mean separation from the center. Earth is almost exactly the same distance from the Sun at aphelion and perihelion, but the orbits of Mars and Mercury depart significantly from a circle. For more information, please visit Bridgewater College's Interactive Planetary Orbits web site

 

Precession - or why the stars change gradually over centuries  

Precession:

Gravitation pull of the Sun and Moon causes a "wobble" in the Earth's axis with a period of 25,000 years (like pushing a gyroscope). This wobble is called precession and has the result of changing the point in the sky where the celestial poles are located and, therefore, changes the "pole star".

This motion was first recorded by Hipparchus in 100 B.C. who noticed differences between ancient Babylonian observations and his own. When the Babylonians were the world power in 2000 B.C., the vernal equinox was in the constellation Aries and the star Thuban (in Draco) was the closest bright star to the north celestial pole. When the Pyramids were built, the north star was Vega.


Sidereal and Synodic time:

HERE

 

Planets

http://physics.uoregon.edu/~jimbrau/astr121/Notes/SS/ss-rotation.jpg

My Very Educated Mother Showed Us Nine Planets

http://ifa.hawaii.edu/~barnes/ast110_06/foss/0908a.png

 

Facts about Pluto

pluto.jpg
In Roman mythology, Pluto is the god of the underworld. The planet received this name perhaps because it’s so far from the Sun that it is in eternal darkness.

http://www.backtowild.com/2007/09/

 

 

 

equator/rotation of the sun -

drewterry

Feb21-08, 10:10 AM

I just learned the sun has an equatorial rotation rate of approximately 25 earth days, and a polar rotation of approximately 31 days.
Intuitively, by the laws of physics, it should be the other way around: longer at the equator and shorter at the poles?

Also, if our solar system is within a larger orbit, is there a year for the sun in that orbit?

What I read is in terms of our year here on Earth - not that there is anything wrong with the Earth year, of course.
I love the year here on Earth.

Any light cast on my shadow is, in advance, very much appreciated.


RetardedBastard Feb21-08, 06:25 PM
 
I'm sure there are others on this board who can explain to you the exact mechanism in GREAT detail (eg., spacetiger), but I'll just stick with the obvious superficial answers to start off :)

I just learned the sun has an equatorial rotation rate of approximately 25 earth days, and a polar rotation of approximately 31 days.
Intuitively, by the laws of physics, it should be the other way around: longer at the equator and shorter at the poles?


You're referring to the sun's "differential rotation" which occurs because the sun is not a big solid ball (it's plasma... super hot ionized gas), different parts rotate at different angular velocities.
This differential rotation applies to other gaseous bodies like the Jovian planets, as well as the disk of the galaxy.

Also, if our solar system is within a larger orbit, is there a year for the sun in that orbit?


If I understand you, you are asking: does the sun itself orbit another body in space?
If that's what you are asking then the answer is YES. Our sun revolves around the galactic center at about 220 km/s, and it takes one "galactic year", or approximately 220 MILLION earth-years, to orbit. Interestingly enough, that's a supermassive BLACK HOLE that the sun is orbiting around!

http://www.physicsforums.com/archive/index.php/t-216968.html

 

Moon

Phases of the Moon:

The Moon is tidally locked to the Earth, meaning that one side always faces us (the nearside), whereas the farside is forever hidden from us. In addition, the Moon is illuminated on one side by the Sun, the other side is dark (night).

Which parts are illuminated (daytime) and which parts we see from the Earth are determined by the Moon's orbit around the Earth, what is called the phase of the Moon (click here for the current phase of the Moon).

As the Moon moves counterclockwise around the Earth, the daylight side becomes more and more visible (i.e. we say the Moon is `waxing'). After full Moon is reached we begi n to see more and more of the nighttime side (i.e. we say the Moon is `waning'). This whole monthly sequence is called the phases of the Moon.

 

HERE

 

Moon-rotation

http://physics.uoregon.edu/~jimbrau/BrauImNew/Chap08/FG08_11.jpg

 

MoonThe Moon's path through the starsMoon

Most people seem to know that the Sun changes its rising and setting positions during the course of a year, and that its noon height in relation to the horizon varies with the seasons. In winter, the Sun rises in the southeast and sets in the southwest, while in summer it rises in the northeast and sets in the northwest, spending much longer in the sky than during winter. At the equinoxes, the sun rises at due east and sets and due west and the length of day and night are the same.

The imaginary line which the sun follows through the heavens is called by astronomers the "ecliptic". It takes the sun one year (365.25 days) to complete one journey around the sky along the Ecliptic. The graphic below shows part of the Ecliptic through the winter night sky, stretching from west to east through the Zodiac constellations Pisces, Aries, Taurus, Gemini, Cancer and Leo.

The Ecliptic line

The 12 Zodiac constellations are those through which the Sun, and the planets, pass on their course through the stars. However, while the planets follow the general path of the Ecliptic, not all of them stick rigidly to it. The Moon is one of these planets.

SEEING THE SEPARATION
The line formed by the Moon's course on its 29-day journey around the sky is tilted slightly to the Ecliptic. This means that, while the Moon's pathline intersects the Sun's pathline (Ecliptic) twice during one lunation, its path is tilted slightly so that it separates from the Sun's path by 5.15 degrees at maximum separation - a distance of roughly 10 moonwidths as seen by the observer.

A good way to visualise this 'separation' of the Moon's path from the Ecliptic is shown in the animation on the right (filesize 72k). You should see the Moon moving through the constellations from west to east - the grey line is the Ecliptic. Note how the Moon's path crosses the Ecliptic twice. Keep watching if you didn't notice it the first time. If you would like to see a larger version of this animation (162k) just click here.

During one 29-day lunation, the Moon seems to spend half its time north of the ecliptic and half its time south. You should be able to see this clearly in the animation.

The Moon's path relative to the ecliptic

THE NODES

The points where the path of the Moon crosses the Ecliptic are called the "Nodes" - specifically the "ascending node", or the point where the Moon crosses the Ecliptic moving south to north, and the "descending node", the point where it crosses heading from north to south. The two nodes are always located 180 degrees apart, or at opposite sides of the sky to each other. It takes the Moon just 14 days to make the journey from one node to the other, but it takes the Sun six months to make a similar 180-degree trip through the sky.

Ascending node
Descending node

The Moon at ascending node taken from the above animation.

The Moon at descending node from the animation shown above.

The nodes themselves slowly move through the sky, so that the Moon's intersection with, and maximum separation from, the Ecliptic move through the constellations slowly over time. This movement is westerly, taking the rotation of the nodes in the opposite direction of the Moon's movement through the stars, which is from west to east.

The ancient Stone Age builders would have been able to see the rotation of the nodes by doing two simple things: (1) keeping an eye on the Moon's position relative to the background stars and (2) watching the Moon's rising and setting positions on the horizon.

RULES OF THUMB

Remember, the Moon crudely follows the path of the Sun and a few simple rules of thumb can be learned from watching it. Firstly, New Moon is the phase of the Moon which is invisible to us, because it occurs when the Moon is in the same position in the sky as the Sun. Full Moon is ALWAYS located 180 degrees from the sun on an east-west plane, so if the Full Moon is rising, the Sun is setting. Now divide this 180-degree distance into two using the Moon.

A week after New Moon is the First Quarter (which should probably be called First Half, because you can see half the face of the Moon), which is located 90 degrees east of the Sun, or in terms of Solar tropical time, three months. In other words, when you see the First Quarter Moon you know the Sun will be in that east-west position in three months' time. When you see Full Moon , that's where the Sun will be in six months' time. A good method of remembering this is the Sun-Moon positions on the solstices. If you see a Full Moon rising around the time of Winter Solstice, mark or remember its rising position - that's roughly where the Sun will rise in six months time - at the Summer Solstice. Notice how in Summer time the Sun is high in the sky while the Full Moon is always low, and in Winter when the Sun is low the Full Moon is always high.

Finally, there's the last quarter (or last half!) which marks out the position the Sun will be in nine months' time.

MOON DIAGRAM
This diagram by Martin Brennan should help show you where the Moon is in relation to the Sun in its various phases. Click on the diagram for a larger version.

Diagram 2 shows the first quarter , which is at its highest point in the sky when the Sun is setting. This phase marks where the Sun will be three months later. Diagram 3 shows the Full Moon , rising in the east while the Sun sets in the west. The Moon's full phase lasts for about three nights. Diagram 4 shows Full Moon at midnight, 180 degrees opposite the Sun. Six months later the Sun will be in this part of the sky.

In diagram 7, the last quarter phase is reached, showing where the Sun will be located in nine months' time. Diagram eight shows the last crescent, which disappears to become "New Moon" before the next lunation begins. It has to be said that Diagram 6 is a bit misleading, showing the last quarter rising but at a slightly odd angle.

CLICK FOR LARGER VERSION

The rotation of the nodes, and knowledge of the Moon's separation from the Ecliptic is crucial to understanding how the ancients predicted eclipses, and crucial to understanding why they marked the so-called "standstills" of the Moon using standing stones, stone circles and other sites.

Some facts to remember:

New Moon

New Moon: In conjunction with the Sun; position of Sun at the present time.

First Quarter

First Quarter: 90 degrees from the Sun; shows position of Sun in three months.

Full Moon

Full Moon: 180 degrees from the Sun; shows Sun's position in six months' time.

Last Quarter

Last quarter: 270 degrees from the Sun; shows where sun will be in nine months.

 

http://www.mythicalireland.com/astronomy/moonmovements/moonpath.html

 

 

 

The Real Romance in the Stars 

By Richard Dawkins

Article in The Independent December 1995

HERE

 

"In the space of one hundred and seventy-six years the Lower Mississippi has shortened itself two hundred and forty-two miles. Therefore ... in the Old Oolitic Silurian Period the Lower Mississippi River was upward of one million three hundred thousand miles long... seven hundred and forty-two years from now the Lower Mississippi will be only a mile and three-quarters long... There is something fascinating about science. One gets such wholesale returns of conjecture out of such a trifling investment of fact."    Mark Twain

 

The Flower of Life

The Flower of Life (commonly abbreviated as FOL) is the modern name given to a geometrical figure composed of multiple evenly-spaced, overlappingThe Flower of Life (click image for links to further images). circles, that are arranged so that they form a flower-like pattern with a sixfold symmetry like a hexagon. The center of each circle is on the circumference of six surrounding circles of the same diameter.

The earliest known example of the Flower of Life symbol dates to at least 400AD, and is possibly much older than that.[1] Throughout human history, philosophers, artists, and architects around the world have known the FOL for its perfect form, proportion, and harmony. It is considered by some pagans to be a symbol of sacred geometry, said to contain ancient, religious value depicting the fundamental forms of space and time.[2][3][4][5] In this (pagan) sense, it is a visual expression of the connections life weaves through all sentient beings, believed to contain a type of Akashic Record of basic information of all living things.[6]

There are many spiritual beliefs associated with the FOL; for example, depictions of the five Platonic Solids are found within the symbol of Metatron's Cube, which may be derived from the FOL pattern. These platonic solids are geometrical forms which are said to act as a template from which all life springs.

Another notable example of that which may be derived from the FOL is the Tree of Life[citation needed]. This has been an important symbol of sacred geometry for many people from various religious backgrounds. Particularly, the teachings of the Kabbalah have dealt intricately with the Tree of Life[citation needed].

http://en.wikipedia.org/wiki/Flower_of_Life

The Flower of Life symbol drawn in red ocre Temple of Osiris at Abydos, Egypt.
The Flower of Life symbol drawn in red ocre Temple of Osiris at Abydos, Egypt.

 

The Seed of Life (a component of the Flower of Life)
The Seed of Life (a component of the Flower of Life)

Tree of Life

 

The symbol of the Tree of Life may be derived from the Flower of Life. The Tree of Life is a mystical concept, a metaphor for commonThe Tree of Life derived from the Flower of Life. descent, and a motif in various world theologies and philosophies.[47] This mystical concept has historically been adopted by some Christians, Jews, Hermeticists, and pagans.[48] Along with the Seed of Life it is believed to be part of the geometry that parallels the cycle of the fruit tree. This relationship is implied when these two forms are superimposed upon each other.[26]

The Tree of Life is most widely recognized as a mystical concept within the Kabbalah, which is used to understand the nature of God and the manner in which He created the world ex nihilo (out of nothing). The Kabbalists developed this concept into a full model of reality, using the tree to depict a "map" of creation. The tree of life has been called the "cosmology" of the Kabbalah.[48]

Some believe the Tree of Life of Kabbalah corresponds to the Tree of Life mentioned in Genesis 2:9.[4

http://en.wikipedia.org/wiki/Flower_of_Life

 

Electromagnetic spectrum

 

The electromagnetic (EM) spectrum is the range of all possible electromagnetic radiation frequencies.[1] The "electromagnetic spectrum" (usually just spectrum) of an object is the characteristic distribution of electromagnetic radiation from that particular object.

The electromagnetic spectrum extends from below the frequencies used for modern radio (at the long-wavelength end) through gamma radiation (at the short-wavelength end), covering wavelengths from thousands of kilometres down to a fraction the size of an atom. It is thought that the short wavelength limit is in the vicinity of the Planck length, and the long wavelength limit is the size of the universe itself (see physical cosmology), although in principle the spectrum is infinite and continuous.

HERE

 

 

Curitiba

Curitiba from Barigüi Park
Curitiba from Barigüi Park
Flag of Curitiba
Flag
Official seal of Curitiba
Seal

Curitiba (pron. IPA[kuɾi'tibɐ] or IPA[kuɾi'tʃibɐ]) is the capital city of the Brazilian state of Paraná. The city has the largest population and also the largest economy in Southern Brazil. The population of Curitiba numbers approximately 1.8 million people (7th largest nationwide) and the latest GDP figures for the city surpass US$17 billion (ranking 4th nationwide) according to IBGE .[1]

Nickname(s): Ctba
Motto: 'A Cidade da Gente' (City of the People)
Location in the State of Paraná
Location in the State of Paraná
Location of Curitiba
Coordinates: 25°25′S 49°15′W / -25.417, -49.25
 

http://en.wikipedia.org/wiki/Curitiba

 

 


More about Myra you can read in Wikipedia: en.wikipedia.org/wiki/Myra 

 

Longitude

Map of Earth
Longitude (λ)
Lines of longitude appear curved in this projection, but are actually halves of great circles.
Latitude (φ)
Lines of latitude appear horizontal in this projection, but are actually circular with different radii. All locations with a given latitude are collectively referred to as a circle of latitude.
The equator divides the planet into a Northern Hemisphere and a Southern Hemisphere, and has a latitude of 0°.

 

History

Main article: History of longitude

Mariners and explorers for most of history struggled to determine precise longitude. Latitude was calculated by observing with quadrant or astrolabe the inclination of the sun or of charted stars, but longitude presented no such manifest means of study. Amerigo Vespucci was perhaps the first to proffer a solution, after devoting a great deal of time and energy studying the problem during his sojourns in the New World.

"As to longitude, I declare that I found so much difficulty in determining it that I was put to great pains to ascertain the east-west distance I had covered. The final result of my labors was that I found nothing better to do than to watch for and take observations at night of the conjunction of one planet with another, and especially of the conjunction of the moon with the other planets, because the moon is swifter in her course than any other planet. I compared my observations with [an almanac]. After I had made experiments many nights, one night, the twenty-third of August, 1499, there was a conjunction of the moon with Mars, which according to the almanac was to occur at midnight or a half hour before. I found that...at midnight Mars's position was three and a half degrees to the east." [2]

By comparing the relative positions of the moon and Mars with their anticipated positions, Vespucci was able to crudely deduce his longitude. But this method had several limitations: First, it required the occurrence of a specific astronomical event (in this case, Mars passing through the same right ascension as the moon), and the observer needed to anticipate this event via an astronomical almanac. One needed also to know the precise time, which was difficult to ascertain in foreign lands. Finally, it required a stable viewing platform, rendering the technique useless on the rolling deck of a ship at sea.

Unlike latitude, which has the equator as a natural starting position, there is no natural starting position for longitude. Therefore, a reference meridian had to be chosen. While British cartographers had long used the Greenwich meridian in London, other references were used elsewhere, including: El Hierro, Rome, Copenhagen, Jerusalem, Saint Petersburg, Pisa, Paris, Philadelphia, and Washington. In 1884, the International Meridian Conference adopted the Greenwich meridian as the universal prime meridian or zero point of longitude.

http://en.wikipedia.org/wiki/Longitude

Conjunction (astronomy and astrology)

Position of the observer

The term conjunction primarily refers to a phenomenon defined only for the position of the observer, not just to a celestial relationship. However, e.g. for moon and sun observed from the earth, conjunction as a classifying term may apply both to the positions of conjunction (both sun and moon observed jointly in one direction or with similar ecliptical longitude) and to opposition (both sun and moon observed separately in opposite directions or with ecliptical longitude 180 degrees apart).

Superior and inferior

Image:Positional astronomy.png

As seen from a planet that is superior, if an inferior planet is on the opposite side of the Sun, it is in superior conjunction with the Sun. An inferior conjunction occurs when the two planets lie in a line on the same side of the Sun. In an inferior conjunction, the superior planet is "in opposition" to the Sun as seen from the inferior planet.

The terms "inferior conjunction" and "superior conjunction" are used in particular for the planets Mercury and Venus, which are inferior planets as seen from the Earth. However, this definition can be applied to any pair of planets, as seen from the one further from the Sun.

A planet (or asteroid or comet) is simply said to be in conjunction, when it is in conjunction with the Sun, as seen from the Earth. The Moon is in conjunction with the Sun at New Moon (or rather Dark Moon).

"Quasi-conjunctions" are also possible; in this scenario, a planet in retrograde motion — always either Mercury or Venus — will "drop back" in right ascension until it almost allows another planet to overtake it, but then the former planet will resume its forward motion and thereafter appear to draw away from it again. This will occur in the morning sky, before dawn; or the reverse may happen in the evening sky after dusk, with Mercury or Venus entering retrograde motion just as it is about to overtake another planet (often Mercury and Venus are both of the planets involved, and when this situation arises they may remain in very close visual proximity for several days or even longer). The quasi-conjunction is reckoned as occurring at the time the distance in right ascension between the two planets is smallest, even though, when declination is taken into account, they may appear closer together shortly before or after this.

http://en.wikipedia.org/wiki/Conjunction_(astronomy)

 

 

http://www.arthistory.sbc.edu/imageswomen/papers/parisaphrodite/botticelli_birth_of_venus.gif

Aphrodite

http://employees.oneonta.edu/farberas/arth/Images/109images/4thc_hellenistic/aph_knidos_det.jpg

 

http://web.tampabay.rr.com/bmerkey/examples/fake-position-fixed.html

This has been a demonstration of faking fixed positioning with CSS for Internet Explorer without scripts. Back to CSS buttons