Radioactive element poisoning

Radioactive elements:A radioactive element is one with an unstable nucleus, which radiates alpha, beta or gamma radiation and gets converted to a stable element.

An element will undergo decay if:

1. It has more than 83 protons.
2. The ratio of protons to neutrons is very close. For example, Carbon, having 6 protons and 6 neutrons (therefore having a 1:1 ratio of protons and neutrons) is a very stable atom. On the other hand, Bismuth, an unstable atom, has 126 neutrons and 83 protons, giving it a 1.52:1 ratio.
3. Nuclides containing certain numbers of protons or neutrons (2, 8, 20, 50, 82, and 126) are more stable than others.
4. Nuclides with even numbers of both protons and neutrons and more stable than those with odd numbers of

Radioactivity:It's a spontaneous and random phenomenon whereby nuclei of certain chemical elements like Uranium, radiate gamma rays (high frequency electromagnetic radiation), beta particles (electrons or positrons) and alpha particles (Helium Nuclei).

Key factor lies in the nucleus of an element:To understand radioactivity, we need to explore the structure of an atomic nucleus. Every nucleus contains neutrons as well as protons. Neutrons are neither positively charged, nor negatively charged, they are neutral particles. Protons are positively charged. And as we know that like charges repel each other while unlike charges attract each other. In the nucleus, protons and neutrons are cramped together in a really very small space.

The protons in the nucleus, all being positively charged, repel each other! So if all the protons repel each other, how does the nucleus stay glued together and remain stable? It is because of the 'Nuclear Force'.

This force is more stronger than the electromagnetic force, but the range of this force is only limited to size of the nucleus, unlike electromagnetic force whose range is infinite. This nuclear force acts between the protons and neutrons, irrespective of the charge and it's always strongly attractive. However, it has limitations of range. So, in the nucleus, there is a constant tussle between the repelling electromagnetic coulomb force of protons and the attractive strong nuclear force.

In a nucleus like Uranium, which has almost 92 protons, coulomb repulsive force becomes too much for the nuclear force to contain. Subsequently, the nucleus is very unstable and radioactive decay occurs and Uranium decays into a more stable element. Such an unstable nucleus like Uranium, when gently tapped by a neutron, splits up into two other nuclei through nuclear fission, releasing tremendous amount of energy in the process! This is the principle on which nuclear energy and nuclear weapons are based.

A full explanation of radioactivity can only be given, if we plunge deep into quantum physics and elementary particle physics.

Types of Radioactive Decay:This decay may occur in any of the following three ways:

alpha decay, in which a nucleus emits an alpha particle, which consists of 2 neutrons and 2 protons and is equivalent to a helium nucleus; beta-minus decay, in which an electron is emitted along with an antineutrino (not shown); gamma decay, in which a nucleus gets rid of its excess energy by emitting a gamma ray photon; and proton decay, the release of a single proton from a nucleus. Proton decay is shown from a normal spherically shaped nucleus and from a deformed, football- shaped nucleus. Researchers have found that the rates of proton radioactivity are different for the two types of nuclei because of their different shapes.

Alpha Decay: Nucleus emits a helium nucleus (called an Alpha Particle) and gets converted to another nucleus with atomic number lesser by 2 and atomic weight lesser by 4.
 

Beta Decay: Beta decay could be of two types; either through emission of an electron or positron (the antiparticle of electron). Electron emission causes an increase in the atomic number by 1, while positron emission causes a decrease in the atomic number by 1. In some cases, double beta decay may occur, involving the emission of two beta particles.
 

Gamma Decay: Gamma decay just changes the energy level of the nucleus.
 

Electron Capture: One of the rarest decay modes is electron capture. In this phenomenon, an electron is captured or absorbed by a proton rich nucleus. This leads to the conversion of a proton into a neutron in the nucleus, along with release of an electron neutrino. This leads to a decrease in atomic number (transmuting the element in the process), while leaving the atomic mass number unchanged.

A radioactive element may have more than one decay mode.

Polonium:

Polonium is a chemical element with the symbol Po and atomic number 84, discovered in 1898 by Marie and Pierre Curie. 

Symbol: Po

Electron configuration: [Xe] 6s2 4f14 5d10 6p4

 Atomic radius: 190 pm

Atomic number: 84

Discovered: 1898

Atomic mass: 209 u

Polonium poisoning:The maximum safe body burden of Po-210 is only seven picograms. A microgram of Po-210, which is no larger than a speck of dust, would certainly deliver a fatal dose of radiation.  

Polonium is only slowly excreted - it has a biological half life of around a month - and this ensures its alpha particles continue to wreak havoc once inside the body. One likely method of administration would be as a soluble salt (citrate or nitrate, for example) added to the victim's food or drink.Once ingested, polonium is rapidly distributed around the body, leaving a trail of reactive radicals in its wake as it steals electrons from any molecule it encounters. Low-level DNA damage from radiation can cause genetic changes that affect cell replication, whereas more severe damage may force the cell to self destruct by apoptosis.

The alleged mysteries:

The body of the former Palestinian leader Yasser Arafat is being exhumed on Tuesday today to test to see if he was the victim of Polonium-210 poisoning. The tests will attempt to establish the cause of his death in Paris in 2004.

Polonium was first discovered by Marie and Pierre Curie in 1898. It is a radioactive element that occurs naturally in the earth's crust.

According to scientists from the University of Chicago Polonium-210 is traditionally used to clear dust from camera lenses or photographic film.

It is poisonous if ingested and it's believe that the Russian dissident Alexander Litvinenko who died in November 2006 was the victim of Polonium-210 poisoning.
 *Note: all pictures thankfully shared from various sources..

Gregor Johann Mendel: Father of Genetics

Scientists Decode Black Dahlias:Vienna, Nov 25, 2012: Scientists have now decoded why some dahlias are black, a rarity, after analyzing as to why the plant displays varying hues, from white to yellow to red to purple.

Dahlia variabilis hort. is a popular garden flower. Continuous dahlia breeding worldwide has led to a huge number of cultivars many of them showing red hues, but black hues of dahlia flowers occur rarely. Credit: Dr. Heidi Halbwirth

To examine the biochemical basis for the distinctive dark coloring of the black dahlia, the research team from the Vienna University of Technology in Austria used pigment, enzyme and gene expression analyses. They determined that the majority of black cultivars have very low concentrations of flavones, as confirmed by low FNS II expression. Since flavones compete with anthocyanin biosynthesis for common intermediates, the lack of flavones favors the accumulation of huge amounts of anthocyanins that are found in black dahlias. The flavonol contents of black dahlias increased slightly parallel to the decrease of flavones. (Citation: Jana Thill, Silvija Miosic, Romel Ahmed, Karin Schlangen, Gerlinde Muster, Karl Stich and Heidi Halbwirth, ''Le Rouge et le Noir': A decline in flavone formation correlates with the rare color of black dahlia (Dahlia variabilis hort.) flowers', BMC Plant Biology 2012, 12:225) 

 *

Every research paper in Genetics 

reminds us a genius of all time

** 

The monk in the garden

Gregor Johann Mendel

The Father of Genetics

***

AKA Gregor Johann Mendel

Born: 22-Jul-1822Birthplace: Hynice, CzechiaDied: 6-Jan-1884Location of death: Brno, CzechiaCause of death: unspecifiedRemains: Buried, Central Cemetery, Brno, Czechia

Gender: MaleReligion: Roman CatholicRace or Ethnicity: WhiteOccupation: Scientist, Botanist, Religion

Nationality: CzechiaExecutive summary: Discovered the laws of inheritance

Father: Anton (farmer)Mother: RosineSister: VeronicaSister: Theresia

    High School: Troppau Gymnasium, Opava, Czechia (1840)
    University: Olmutz Philosophical Institute (1840-43)
    Theological: Brünn Theological College, Brno, Czechia (1847)
    Teacher: Znojmo Gymnasium, Znojmo, Czechia (1849-51)
    Teacher: Mathematics and Biology, University of Vienna (1851-54)
    Administrator: Abbot and Prelate, St Thomas's Abbey, Brno, Czechia (1854-68)

    Ordained by the Roman Catholic Church 6-Aug-1847
    Asteroid Namesake 3313 Mendel
    Lunar Crater Mendel (48.8° S, 109.4° W, 138 km. diameter)
    Martian Crater Mendel (58.8° S, 161° E, 79 km. diameter)

The Lost and Found Genius of Gregor Mendel: Most people know that Gregor Mendel, the Moravian monk who patiently grew his peas in a monastery garden, shaped our understanding of inheritance. But people might not know that Mendel's work was ignored in his own lifetime, even though it contained answers to the most pressing questions raised by Charles Darwin's revolutionary book, ON ORIGIN OF THE SPECIES, published only a few years earlier. Mendel's single chance of recognition failed utterly, and he died a lonely and disappointed man (Before his death in 1884 he wrote, "I am convinced that it will not be long before the whole world acknowledges the results of my work,"). Thirty-five years later, his work was rescued from obscurity in a single season, the spring of 1900, when three scientists from three different countries nearly simultaneously dusted off Mendel's groundbreaking paper and finally recognized its profound significance. The perplexing silence that greeted Mendel's discovery and his ultimate canonization as the father of genetics make up a tale of intrigue, jealousy, and a healthy dose of bad timing. 

In 1857, Austrian monk Gregor Mendel decided to breed pea plants in the large monastery garden of Brunn. He loved botany (studying plants) and he had very much wanted to become a high school teacher. Unfortunately, he had failed the teaching exam three times, so he had to be content with living as a monk. It took him eight years and 30,000 pea plants to discover these natural laws of heredity (now known as the Mendelian Laws). Afterwards, Mendel wished to publish his findings, but feared that no one would listen to him because he was only a monk and not even qualified to teach high school! Nevertheless, he sent his reports to the most famous botanist in Europe, Karl Wilhelm von Nageli of Switzerland, hoping to gain his sponsorship (support of his work). von Nageli ignored Mendel's work, though, and sent it back to him. Mendel was able to get his paper published in a scientific journal several years later, but - just as he had feared - no one acknowledged it because he was an unsponsored amateur. Saddened, he gave up botany and devoted his days to monastic life. Mendel died in 1884. It was nearly forty years later when his writings and research were rediscovered and found to be true.

On New Year's Eve, 1866, Gregor Mendel wrote to the prominent Swiss botanist Carl Nägeli to tell him about his now classic experiments with Pisum peas. In the margins of the letter, Nägeli scribbled a note: "only empirical and not rational."

MENDEL, Gregor (1822-84). 

Mendel was born on July 22, 1822 in Heizendorf, Austria, (now known as Hyncice in Czechoslovakia). He was born Johann Mendel into a poor farming family. At that time it was difficult for poor families to obtain a good education and the young Mendel saw the only way to escape a life of poverty was to enter the monastery at Brunn in Moravis, (now Brno in Czechoslovakia). Here he was given the name Gregor. This monastery was the Augustinian Order of St Thomas, a teaching order with a reputation as a centre of learning and scientific enquiry.

He took the name Gregor when he entered the monastery in Brunn, Moravia (now Brno, Czech Republic) in 1843. He studied for two years at the Philosophical Institute in Olmutz (now Olomouc, Czech Republic), before going to Brunn. He became a priest in 1847. For most of the next 20 years he taught at a nearby high school, except for two years of study at the University of Vienna (1851-53). In 1868 Mendel was elected abbot of the monastery.

To enable him to further his education, the abbot arranged for Mendel to attend the University of Vienna to get a teaching diploma. However, Mendel did not perform well. He was nervous and the University did not consider him a clever student. Mendel's examiner failed him with the comments, " he lacks insight and the requisite clarity of knowledge". This must have been devastating to the young Mendel. who in 1853 had to return to the monastery as a failure.

Mendel's famous garden-pea experiments began in 1856 in the monastery garden. He proposed that the existence of characteristics such as blossom color is due to the occurrence of paired elementary units of heredity, now known as genes. Mendel presented his work to the local Natural Science Society in 1865 in a paper entitled "Experiments with Plant Hybrids." (Gregor Mendel 1865.Versuche uber Pflanzen-Hybriden. Verh. Naturfosch. Ver. Brunn, Vol 4:3-47.) Administrative duties after 1868 kept him too busy for further research. He lived out his life in relative obscurity, dying on Jan. 6, 1884. In 1900, independent research by other scientists confirmed Mendel's results.

Mendel's garden plot at the Augustine monastery in Brno, Czech Republic.

He published his results in the Journal of the Brno Natural History Society in 1866, writing:

"It is now clear that the hybrids form seeds having one or other of two differentiating characters, and of these one half develop again the hybrid form, while the other half yield plants which remain constant and receive the dominant or the recessive characters in equal numbers."

Mendel's field notes

While Mendel's research was with plants, the basic underlying principles of heredity that he discovered also apply to people and other animals because the mechanisms of heredity are essentially the same for all complex life forms.

Through the selective cross-breeding of common pea plants (Pisum sativum) over many generations, Mendel discovered that certain traits show up in offspring without any blending of parent characteristics.  For instance, the pea flowers are either purple or white--intermediate colors do not appear in the offspring of cross-pollinated pea plants.  Mendel observed seven traits that are easily recognized and apparently only occur in one of two forms:

1.	flower color is purple or white	5.	seed color is yellow or green
2.	flower position is axil or terminal	6.	pod shape is inflated or constricted
3.	stem length is long or short	7.	pod color is yellow or green
4.	seed shape is round or wrinkled

Experiments on plant hybridization:

In cross-pollinating plants that either produce yellow or green pea seeds exclusively, Mendel found that the first offspring generation (f1) always has yellow seeds.   However, the following generation (f2) consistently has a 3:1 ratio of yellow to green

 

This 3:1 ratio occurs in later generations as well.   Mendel realized that this was the key to understanding the basic mechanisms of inheritance.

He came to three important conclusions from these experimental results:

1.	that the inheritance of each trait is determined by "units" or "factors" that are passed on to descendents unchanged      (these units are now called genes)
2.	that an individual inherits one such unit from each parent for each trait
3.	that a trait may not show up in an individual but can still be passed on to the next generation.

It is important to realize that, in this experiment, the starting parent plants were homozygous for pea seed color.  That is to say, they each had two identical forms (or alleles) of the gene for this trait--2 yellows or 2 greens.  The plants in the f1 generation were all heterozygous.   In other words, they each had inherited two different alleles--one from each parent plant.  It becomes clearer when we look at the actual genetic makeup, or genotype , of the pea plants instead of only the phenotype, or observable physical characteristics.

Note that each of the f1 generation plants (shown above) inherited a Y allele from one parent and a G allele from the other.  When the f1 plants breed, each has an equal chance of passing on either Y or G alleles to each offspring.

With all of the seven pea plant traits that Mendel examined, one form appeared dominant over the other, which is to say it masked the presence of the other allele.  For example, when the genotype for pea seed color is YG (heterozygous), the phenotype is yellow.  However, the dominant yellow allele does not alter the recessive green one in any way.   Both alleles can be passed on to the next generation unchanged.

Mendel's observations from these experiments can be summarized in two principles:

1.	the principle of segregation
2.	the principle of independent assortment

According to the principle of segregation, for any particular trait, the pair of alleles of each parent separate and only one allele passes from each parent on to an offspring.  Which allele in a parent's pair of alleles is inherited is a matter of chance.  We now know that this segregation of alleles occurs during the process of sex cell formation (i.e.meiosis).

Segregation of alleles in the production of sex cells

According to the principle of independent assortment, different pairs of alleles are passed to offspring independently of each other.  The result is that new combinations of genes present in neither parent are possible.  For example, a pea plant's inheritance of the ability to produce purple flowers instead of white ones does not make it more likely that it will also inherit the ability to produce yellow pea seeds in contrast to green ones.  Likewise, the principle of independent assortment explains why the human inheritance of a particular eye color does not increase or decrease the likelihood of having 6 fingers on each hand.  Today, we know this is due to the fact that the genes for independently assorted traits are located on different chromosomes 

These two principles of inheritance, along with the understanding of unit inheritance and dominance, were the beginnings of our modern science of genetics.

Gregor Mendel's genius spelt out in a pea-flavoured Google doodle. Born into poverty on a farm in Austria, Gregor Mendel and his peas went on to sow the seeds of modern genetics

*Note: all pictures thankfully shared from various sources.

 

Turn down the heat: World Bank warns for disaster

The warnings come as nations meet in Doha, Qatar from November 26 for the next major round of international climate change negotiations.

It is the first time a Gulf state has hosted global climate negotiations

Kim, a physician and former president of Dartmouth College who was tapped for the World Bank by US President Barack Obama, said that 97 percent of scientists agreed that human activity was causing climate change.

“A 4°C world is likely to be one in which communities, cities and countries would experience severe disruptions, damage, and dislocation,” the bank report said. “There is no certainty that adaptation to a 4°C world is possible.”

The report noted that a drop in average temperature of around 4.5 degrees Celsius — more than 7 degrees Fahrenheit — triggered the last ice age, and it predicted that a temperature increase of that magnitude would similarly reshape the planet.

 In what World Bank President Jim Yong Kim acknowledged was a “doomsday scenario,” a new bank study cited the 4 degree increase as a threshold that would likely trigger widespread crop failures and malnutrition and dislocate large numbers of people from land inundated by rising seas.

"A 4 degree warmer world can, and must be, avoided -- we need to hold warming below 2 degrees," World Bank Group president Jim Yong Kim said.

 "Lack of action on climate change threatens to make the world our children inherit a completely different world than we are living in today. Climate change is one of the single biggest challenges facing development, and we need to assume the moral responsibility to take action on behalf of future generations, especially the poorest," he said.

 The report says the 4°C scenarios are potentially devastating: the inundation of coastal cities; increasing risks for food production potentially leading to higher under and malnutrition rates; many dry regions becoming dryer, wet regions wetter; unprecedented heat waves in many regions, especially in the tropics; substantially exacerbated water scarcity in many regions; increased intensity of tropical cyclones; and irreversible loss of biodiversity, including coral reef systems.

It said extreme heat waves, that without global warming would be expected to occur once in several hundred years, will be experienced during almost all summer months in many regions.

The effects would not be evenly distributed.

From the Bonn Climate Change Talks, which were held June 2nd-13th 2008,

According to a new report from the Institute of Policy Studies in Washington DC, the Bank’s role in carbon markets is "dangerously counterproductive." The World Bank is "playing both sides of the climate crisis," concludes Janet Redman, main author of the report. "It is making money off of causing the climate crisis and then turning around and claiming to solve it," she says. Instead of encouraging clean energy investors, the Bank is lending much of its financial support to the fossil fuel industry.

"We’re not at the moment seeing the leadership from industrialized countries which I think is essential," warned de Boer, midway through the Bonn meeting. As the talks ended, he described the task of reaching agreement by the end of 2009 as "daunting." "It could well be said that we have been beating around the bush," said Chandrashekhar Dasgupta, India’s representative. The United States, Canada and Australia, in particular, were accused by environmentalists of limiting progress.

Astronomical Concepts

amateur  astronomy series #5

Celestial sphere: Inside of an imaginary sphere, with the  Earth at it's center, upon which all celestial bodies are assumed to be projected.

The Earth rotating within a relatively small-diameter Earth-centered celestial sphere. Depicted here are stars (white), the ecliptic (red), and lines of right ascension and declination (green) of the equatorial coordinate system.

The most obvious behavior of the celestial sphere is it's apparent daily east to west rotation, due to the axial spin of the earth.

The point which the stars appear to move around is one of the celestial poles.

The  celestial equator is the line around the celestial sphere that is half way between the celestial poles

The Altitude/ azimuth coordinate system can be used to describe a direction of view (The Azimuth angle) and a height in the sky (the Altitude angle).

The azimuth angle is measured clockwise round from due north. Hence North itself is 0°, East 90°, South-West 135° and so on. The altitude angle is measured up from the horizon.

Looking directly up (at the zenith) would be 90°, half way between the zenith and the horizon is 40° and so on. The point opposite zenith is called  nadir.

The altitude and azimuth values for an object in the sky change with time and location of the observer.

The celestial latitude and longitude
right ascension (α) or hour angle (h)  (horizontal) and declination (δ) (vertical)

RA/DC coordinate system uses two angles to describe positions in the sky. These angles are measured from standard points on the celestial sphere.

Right ascension and declination are to the celestial sphere what longitude and latitude are to terrestrial map makers.

celestial pole: The northern celestial pole has a declination of 90°, the celestial equator has a declination of 0° and the southern celestial pole has a declination of -90°.

Right ascension is measured as an angle round from a point in the sky known as the first point of Aries, in the same way that longitude is measured around the from Green witch. One hour of RA= 15° of arc

This was an accurate description of it's position thousands of years ago, but precaution has now carried it into the constellation of Pisces.

Some notes:

ecliptic: Apparent yearly path of the sun against the background of stars caused by the earth's orbital motion. Because of the 23.5°, "obliquity of ecliptic'. The annual path of the sun takes it through the familiar 12 constellations of the zodiac.

zodiac: Belt of constellations, roughly 8° on either side of the ecliptic, through which the sun, moon and planet appears to pass. The zodiac includes 12 familiar constellations, named after constellations they contained at the time of ancient Greeks.

In astrology zodiac is divided into 12 equal signs, each 30° long.

Constellation  are groupings of stars that are visually close to one another in the sky.

Polaris: A pole star is a visible star, preferably a prominent one, that is approximately aligned with the Earth's axis of rotation; that is, a star whose apparent position is close to one of the celestial poles, and which lies approximately directly overhead when viewed from the Earth's North Pole or South Pole. A similar concept also applies to other planets than the Earth. In practice, the term Pole Star usually refers to Polaris, which is the current northern pole star, also known as the North Star.

The south celestial pole currently lacks a bright star like Polaris to mark its position. At present, the naked-eye star nearest to this imaginary point is the faint Sigma Octantis, which is sometimes known as the South Star.

# In 14,000 years time Polaris will be nearly 47° away from the celestial pole.

# Polaris, North Star 90°

# Sigma Octantis -90 °

sidereal day and sidereal time (360° rotation, i.e. 23 hrs, 56 mins, 4.091 secs) and solar day and solar time (more than 360°)

Right ascension can be measured in angular terms. However, it is more common to use units of time (hours, minutes, seconds or h m s).

Astronomer measure time by the rotation of the Earth relative to the star, that is exactly 360° of axial rotation, rather than to the sun. Their sidereal time scale has a day of 24 sidereal hours, which in terms of civil time is 24 hours, 56 minutes and 4.091 seconds long.

The beginning of the sidereal day is when the First Point of Aries lies on the Meridian, the great circle of linking the north and south points and passing directly overhead. After 24 sidereal ours it will be in that position again. At 1 h sidereal time the sky will have rotated 15°.

Angles are measured in degree. The degree is divided in 60 minutes of arc (also known a arc-minutes). Each minute of arc is further subdivided i sixty seconds of arc (or arc-seconds). Thus one degree is equal to 3600 seconds of arc (further finer grades, as milli arc-seconds i.e. one thousandth of an arc-second).

Notation

90°  15'  12"

               12.432"

90.2533° 

Astronomical system of units

# An astronomical unit (abbreviated as AU, au, a.u., or ua) is a unit of length equal to exactly 149,597,870,700 metres (92,955,807.273 mi)^[1] or approximately the mean Earth–Sun distance by the best current (2009) estimate of the International Astronomical Union (IAU)

# Light year: speed of light 300,000 kms/second, i.e. 9.5 trillion kms= 1 light year
( the speed of light in a vacuum is defined as c₀ = 299,792,458 m/s in a vacuum, in accordance with the SI units.)

# Parsec, the distance of an object that has an annual parallax of one second of arc.

The astronomical distance unit parsec uses the AU as a baseline and an angle of one arcsecond for parallax. 1 AU and 1 pc not to scale.

Transits of Venus across the face of the Sun were, for a long time, the best method of measuring the astronomical unit, despite the difficulties (here, the so-called "black drop effect") and the rarity of observations.

*Note: all pictures thankfully shared from various sources..























*Note: all pictures thankfully shared from various sources..

Celestial Coordinates

amateur  astronomy series #4

Coordinate systems can specify a position in 3-dimensional space, for specifying positions of celestial objects: satellites, planets, stars, galaxies, and so on......are analogous to the geographic coordinate system used on the surface of the Earth, with the same fundamental (x,y) plane and primary (x-axis) direction. Each coordinate system is named for its choice of fundamental plane.

A star's galactic (yellow), ecliptic (red) and equatorial (blue) coordinates, as projected on the celestial sphere. Ecliptic and equatorial coordinates share the vernal equinox (magenta) as the primary direction, and galactic coordinates are referred to the galactic center (yellow). The origin of coordinates (the "center of the sphere") is ambiguous

The Coordinate systems in use:

1. Equatorial Coordinates:

Declination (latitude): +90°, -90°

Right Ascension (longitude): hours, minutes, seconds

2. The Horizontal Coordinate System uses the observer's horizon as the plane of reference.

Altitude: angular measure of an object above the horizon.

Azimuth: being measured westward around the horizon from north.

3. Ecliptic Coordinates are based upon the plane of the Ecliptic and uses the measure of,

Celestial Latitude (Ecliptic Latitude): is measured in degrees north and south of the ecliptic.

Celestial Longitude (Ecliptic Longitude) is measured in degrees eastward along the ecliptic from the first point of the Aries.

4. galactic Coordinate System takes the plane of the Galaxy and the Galactic Center (RA 17h 46m dec -28° 56') as it's reference points.

Galactic Latitude is measured from 0° at tghe Galactic Equator to 90° at tghe Galactic Pole, while

Galactic Longitude is measured from 0° to 360° eastwards along the Galactic Equator.

Summary of the main Coordinate systems:

• 1 Coordinate systems
  • 1.1 Horizontal system
  • 1.2 Equatorial system
  • 1.3 Ecliptic system
  • 1.4 Galactic system
  • 1.5 Supergalactic system

Notation

• Horizontal coordinates

• A - azimuth
• a - altitude

• Equatorial coordinates

• α - right ascension
• δ - declination
• h - hour angle

• Ecliptic coordinates

• λ - ecliptic longitude
• β - ecliptic latitude

• Galactic coordinates

• l - galactic longitude
• b - galactic latitude

• Miscellaneous

• λ_o - observer's longitude
• φ_o - observer's latitude
• ε - obliquity of the ecliptic
• θ_L - local sidereal time
• θ_G - Greenwich sidereal time

Coordinate system [1]	Center point (Origin)	Fundamental plane (0º vertical)	Poles	Coordinates		Primary direction (0º horizontal)
				Vertical	Horizontal
Horizontal (also called Alt/Az or El/Az)	observer	horizon	zenith / nadir	altitude (a) or elevation	azimuth (A)	north or south point of horizon
Equatorial	center of the Earth (geocentric) / center of the Sun (heliocentric)	celestial equator	celestial poles	declination (δ)	right ascension (α) or hour angle (h)	vernal equinox
Ecliptic		ecliptic	ecliptic poles	ecliptic latitude (β)	ecliptic longitude (λ)
Galactic	center of the Sun	galactic plane	galactic poles	galactic latitude (b)	galactic longitude (l)	galactic center
Supergalactic		supergalactic plane	supergalactic poles	supergalactic latitude (SGB)	supergalactic longitude (SGL)	intersection of supergalactic plane and galactic plane

*Note: all pictures thankfully shared from various sources..