Saturday, May 26, 2012

Star colors and color blindness

Star colors in visible spectrum
Clark Planetarium
In astronomy stellar classification is based on their spectral characteristics.

The spectral class of a star is a designated class of a star describing the ionization of its chromosphere, what atomic excitations are most prominent in the light, giving an objective measure of the temperature in this chromosphere.

Light from the star is analyzed by
  • splitting it up by a diffraction grating
  • subdividing the incoming photons into a spectrum exhibiting a rainbow of colors
  • interspersed by absorption lines
  • each line indicating a certain ion of a certain chemical element
Most stars are currently classified using the letters O, B, A, F, G, K, and M, where O stars are the hottest and the letter sequence indicates successively cooler stars up to the coolest M class.

Oh, Be A Fine Gentleman/Girl, Kiss Me

O - Blue
B - Blue-white
A - White
F - Yellow-white
G - Yellow
K - Orange
M - Red

even though the actual star colors perceived by an observer may deviate from these colors depending on visual conditions and individual stars observed.

Color blindness
The above quoted wikipedia article wisely underlines the importance of the observer, the person who is looking at the light in nature or in photographs and judges the color. For a philosopher might ask "is there such a thing as red or is it just in the eyes of the looker?"

How do we perceive that a given electromagnetic wavelength, for example the Hydrogen alpha emission line, is red (rouge... rooi... vermelho... чырвоны )?

Well - by looking at it through our eyes. Normal healthy eyes and brains have the wonderful ability to make a distinction between fine shades of color, between blue and blue-white for example.

A color blind person cannot see stellar or other colors at all and people with color deficiency see them wrongly?


Well, God of Israel has created a truly marvellous BGR instrument and set two of them on our foreheads which, like the other things He has done, can become dysfunctional or break altogether.

Cross section of human eye. wikimedia
The typical human retina contains two kinds of light cells: the rod cells (active in low light) and the cone cells (active in normal daylight). Normally, there are three kinds of cones, each containing a different pigment, which are activated when the pigments absorb light.

The spectral sensitivities of the cones differ; one is maximally sensitive to short wavelengths, one to medium wavelengths, and the third to long wavelengths, with their peak sensitivities in the blue, yellowish-green, and yellow regions of the spectrum, respectively.

The absorption spectra of all three systems cover the visible spectrum. These receptors are often called S cones, M cones, and L cones, for short, medium, and long wavelength; but they are also often referred to as blue cones, green cones, and red cones, respectively.

Although these receptors are often referred to as "blue, green, and red" receptors, this terminology is not very accurate, especially as the "red" receptor actually has its peak sensitivity in the yellow region. The sensitivity of normal color vision actually depends on the overlap between the absorption spectra of the three systems: different colors are recognized when the different types of cone are stimulated to different degrees.

Red light, for example, stimulates the long wavelength cones much more than either of the others, and reducing the wavelength causes the other two cone systems to be increasingly stimulated, causing a gradual change in hue.

Many of the genes involved in color vision are on the X chromosome, making color blindness more common in males than in females because males have only one X chromosome, while females have two. Because this is an X-linked trait an estimated 2-3% of women have a 4th color cone and can be considered tetrachromats although it is not clear that this provides an advantage in color discrimination.

Wonder of creation - pairing of EM radiation and Retina receptors!

The eye is designed to receive strong or dim light and has BGR sensitivity to different wavelengths of visible light.

This is how we see stellar colors and their finest shades.

Except for those who suffer from color blindness.

Colors in space

Pinwheel in many colors!
Chandra photo album
Astronomers main evidence for the study of night sky is to examine the electromagnetic radiation that heavenly objects transmit in the Universe. Sophisticated instruments have been developed and installed either on the surface of planet Earth or on orbits in the sky to detect different wavelengths of this cosmic radiation.

The fabulous Chandra X-ray photo of the Pinwheel galaxy is a combination of light from different wavelengths.

Our eyes see also earthly objects through the light they emit or reflect or block in shadows. Many telescopes collect light in the visible range of the spectrum familiar to us from the rainbow. Other instruments have been created in order to detect light in the infra-red or ultraviolet ranges invisible to human eyes.

Branches of Astronomy by electromagnetic wavelengths

Cos B Gamma-ray telescope. NASA
  • Gamma-ray astronomy has developed into a special branch of space sciences since 1960'ies. 
  • Special receivers detect X-rays like the NASA flagship Chandra X-ray Observatory.   
  • Radio astronomy is looking - or rather listening - to EM waves emitted in the radio frequencies - in this link is an image gallery of some of worlds most important devices including sophisticated Very Large Interferometry (VLBI) systems the pride of the countries that have them. 
  • Cosmic microwave background astronomy is unravelling deep secrets of the cosmos. Currently scientists hopes are focused especially on the BICEP2 cosmic microwave background polarization experiment located at the South Pole.

Friday, May 25, 2012

Andromeda Galaxy is near by

Andromeda and Milky Way are the largest galaxies in the Local group. ref

The distance from us to the nearest galaxy Andromeda is estimated at about 2.5 million light years. 

So how near is 2.5m ly? Could we go there or have visitors from there here upon Earth?

Let us try to understand the distance in terms of time it would travel there and back at light speed.

If we were to broadcast today 25 May 2012 a radio signal towards Andromeda and if someone out there would catch our signal, figure out exactly from where it came and kindly immediately responds to our signal with an identical radio signal, a kind of inter-galactic "ping", we would have that response back in our receivers clear and loud 25 May 5002012 AD.

How long period of time is that?

One point of reference is the fact that humans have existed on planet Earth as a distinct species approximately that time - 5002012 years take or leave some. Evolutionary biologists are estimating that according to the DNA records we humans were separated from chimpanzees in Africa about five million years ago.

Such a point of reference gives some perspective to astronomic distances and dates.

Red and blue clouds in deep space


IC 1795, a star forming region in Cassiopeia
APOD ©2011 Bob and Janice Fera (Fera Photography)
"Ionized by ultraviolet light from energetic young stars, a hydrogen atom emits the characteristic H-alpha light as its single electron is recaptured and transitions to lower energy states." (APOD)

(Ionization is the process of converting an atom or molecule into an ion by adding or removing charged particles such as electrons or ions. An ion is an atom or molecule in which the total number of electrons is not equal to the total number of protons, giving it a net positive or negative electrical charge. wikipedia)

H-alpha emission

Hydrogen alpha emission

In the simplified Rutherford Bohr model of the hydrogen atom, the Balmer lines result from an electron jump between the second energy level closest to the nucleus, and those levels more distant. The transition depicted here produces an H-alpha photon, and the first line of the Balmer series. For hydrogen (Z = 1) this transition results in a photon of wavelength 656 nm (red).

The visible hydrogen emission spectrum lines in the Balmer series. H-alpha is the red line at the right. wikimedia

Update: APOD 7 June 2012 has an impressive image of Venus transit taken with narrowband H-alpha filter. The red light from hydrogen emission shows interesting details on the surface of Sun not visible in regular photos.


Metrope's Reflection nebula in Pleiades
APOD ©2012 Leonardo Orazi
"The blue color typical of reflection nebula is caused by blue light being more efficiently scattered by the carbon dust than red light. The brightness of the nebula is determined by the size and density of the reflecting grains, and by the color and brightness of the neighboring star(s)." (APOD)

Friday, May 18, 2012

Andromeda Galaxy in Ultraviolet

Another gorgeous image in Astronomy Picture of the Day.

I store the link to this extraordinary beautiful and clear image of Andromeda here for easy of reference later on as the APOD site has so many images.

UV light
Ultraviolet (UV) light is electromagnetic radiation with a wavelength shorter than that of visible light, but longer than X-rays, in the range 10 nm to 400 nm, and energies from 3 eV to 124 eV.

It is named because the spectrum consists of electromagnetic waves with frequencies higher than those that humans identify as the colour violet. These frequencies are invisible to humans, but visible to a number of insects and birds. They are also indirectly visible, by causing fluorescent materials to glow with visible light.

Although ultraviolet radiation is invisible to the human eye, most people are aware of the effects of UV through sunburn, and in tanning beds. A great deal (>97%) of mid-range ultraviolet (almost all UV above 280 nm and most above 315 nm) is blocked by the ozone layer, and would cause much damage to living organisms if it penetrated the atmosphere.

After atmospheric filtering, only about 3% of the total energy of sunlight at the zenith is ultraviolet, and much of this is near-ultraviolet that does not cause sunburn. An even smaller fraction is responsible for sunburn and also the formation of vitamin D (peak production occurring between 295 and 297 nm) in all organisms that make this vitamin (including humans).

The UV spectrum thus has many effects, both beneficial and damaging, to human health.

Thursday, May 10, 2012

Fiat lux! James Webb Space Telescope MIRI

The BBC Science correspondent Jonathan Amos gives a compact interim report on the current status of the James Webb Space Telescope on the occasion of the signing of the MIRI agreement with NASA. 

The task of the highly sensitive Mid-Infrared Instrument MIRI is to look for the first light of creation - as the Bible says

And God said, “Let there be light”; and there was light
Genesis 1:3 KJ21

Faint fossile light from the beginning

The earliest fossil light in the cosmos dates back over 13 billion human years. It is faint and can best be detected on infra-red wavelengths that penetrate also through the big dust and gas clouds that are hiding visible light from such distant objects in time and space.

Among other things Jonathan Amos tells about MIRI

Miri is a complex design, and will operate at minus 266C. This frigid state is required for the instrument's detectors to sample the faintest of infrared sources. Everything must be done to ensure the telescope's own heat energy does not swamp the very signal it is pursuing.

The hardware for Miri has been developed by institutes and companies from across Europe and America.

The job of pulling every item together and assembling the finished system has had its scientific and engineering lead in the UK.

Miri has just gone through a rigorous mechanical and thermal test campaign at the Rutherford Appleton Laboratory (RAL) in Oxfordshire.

The next step is for Miri to be put in a special environment-controlled shipping box, so it can travel to the US space agency's Goddard centre. The Maryland facility is where the final integration of James Webb will take place.

If all goes well the James Webb Space Telescope will be launched to its position 1.5 million kilometers from Earth in an ESA Arianne rocket in 2018.

If all goes well - life does not come with guarantees!

We wish God's blessing to the project and to all participating in this major scientific enterprise with so many hurdles on its way and with so much promise!

Friday, May 4, 2012

al Qaida in the sky?

Alkaid. Science blogs

Alkaid, the seventh star in the tip of the Great Bear's tail get its name from the Arabic قائد بنات نعش qā'id bināt naʿsh which means Leader of the Daughters of the Bier.

The bright star is fathomed as the leader among the three mourners following the bier (the cup of the Dipper). Every night the solemn procession slowly and silently walks around the North pole.

17th century satirical poet Samuel Butler wrote wittingly about the meaning of Alkaid in Medieval Astrology when describing his anti-hero Sir Hudibras:

Sir Hudibras
Cardan believ'd great states depend
Upon the tip o' th' Bear's tail's end;
That, as she whisk'd it t'wards the Sun,
Strew'd mighty empires up and down;
Which others say must needs be false,
Because your true bears have no tails.
Samuel Butler Hudibras p.442. 1674-78  

Butler also wrote something else that fits also modern al Qaida but touches militant religiosity everywhere regardless of whether it appears among Christians, Jews, Muslims, Hindus or other people. (For violent defence of one's faith and aggressive behaviour in order to reach religious goals is a global trait in humanity.)

Sir Hudibras
For his Religion, it was fit
To match his learning and his wit;
'Twas Presbyterian true blue;
For he was of that stubborn crew
Of errant saints, whom all men grant
To be the true Church Militant;
Such as do build their faith upon
The holy text of pike and gun;
Decide all controversies by
Infallible artillery;
And prove their doctrine orthodox
By apostolic blows and knocks;
Call fire and sword and desolation,
A godly thorough reformation,
Which always must be carried on,
And still be doing, never done;
As if religion were intended
For nothing else but to be mended.
Samuel Butler Hudibras

Cute, but in Arabic language...
In 2007 Dr Martin Rundkvist was wondering the association of the words Alkaid and al Qaida.  He took, however, the prudent step and asked an expert on Arabic language about the linguistics - how the two words are connected. This is the definitive answer he received:

Says Dear Reader Dilworth (who should know, being a professor of Arabic), "The star in the big bear constellation is called al-qaa'id in Arabic (I checked this on several Arabic astronomy sites) with a hamza in the middle (not an Ayn) which means that it is the active participle of the verb 'to lead', with the root qaaf waaw daal. Al-Qaeda is spelled with an Ayn in the middle (root qaaf, Ayn, daal) and it has the basic meaning mentioned: to sit.  The two words are not only not cognate, they are not at all related."
Rundkvist's blog

(Click the link for more discussions on the subject.)

Despite of the linguistic crushing of the "sounds similar" theory, I found the verses of Samuel Butler on Alkaid and on religious militantism still worth referring to.  Dr Rundkivst might as "a Swedish archaeologist, journal editor, public speaker, chairman of the Swedish Skeptics Society, atheist, lefty liberal, bookworm, and father of two" approve with this since also Voltaire was an admirer of Butler's anti-religious wit!

Thursday, May 3, 2012

Yet another unimaginable image - Messier 106

There is a truly unimaginable close-up image of the majestic galaxy Messier 106 in NASA Astronomy Picture of the Day APOD.

BTW isn't our choice of words sometimes amusing considering, for example, how brilliantly luminous the black hole actually is...

"It is also a Seyfert II galaxy, which means that due to x-rays and unusual emission lines detected, it is suspected that part of the galaxy is falling into a supermassive black hole in the center" (wikipedia)

St Augustine versus Bible

Professor Knuuttila notes in the study described in the previous blog that according to Saint Augustine creation "...took place through God's omnipotence without toil, effort, or industry.

How does Mister Augustine know this?

I see no other source for such a statement as the Philosophers love for accurate definitions in the purest linguistic world of ideas in Neo-Platonism and its emanations?

For the good old practical Bible tells us that the creating of everything actually was quite a job for God. We know this since after completing the work He took a well-deserved rest!

Thus the heavens and the earth were finished, and all the host of them. And on the seventh day God ended His work which He had made; and He rested on the seventh day from all His work which He had made. And God blessed the seventh day and sanctified it, because in it He had rested from all His work which God created and made.
Gen 2:1-3 

Sabbath observance
Sabbath observance is of cosmic importance in Judaism and a hall-mark of the religion.

Trying to emulate the total rest God has commanded on Sabbath day is a major challenge in Judaism and the source of constant worry. Really resting on Sabbath from everything that can be considered work is actually so difficult that some Jewish scholars have suggested "if Sabbath is kept properly even once Messiah will come!"

Since the divine rest on the Seventh Day is of such fundamental importance to the religion of the people of God Saint Augustine and the rest of us should not dismiss it so lightly ultimately relying on our brains and not on what is written in the Holy Scriptures.

If I am wrong about St Augustine in this, please fix my error!

Time and Creation in Augustine - Simo Knuuttila

The Cambridge Companion to Augustine  8

Time and creation in Augustine
Simo Knuuttila

Augustine's most extensive discussions of philosophical and theological cosmology are found in his commentaries on Genesis (De Genesi contra Manichaeos, De Genesi ad litteram imperfectus liber, De Genesi ad litteram libri duodecim), in the last three books of the Confessions, and in Books 11 and 12 of the De civitate Dei. The main lines of his view of the creation are as follows.

  • God created both the spiritual realm of angels and the visible world, including the incarnated souls, out of nothing (ex nihilo), without any pre-existing matter or other things outside God, so that ontologically new beings came into existence. 
  • The creation was based on an eternal free act of God's perfectly good will
  • It took place through God's omnipotence without toil, effort, or industry
  • God created simultaneously all first actualized things and, through “seminal reasons” inherent in them, the conditions of all those things which were to come up to the end of the world. 
  • God is the only creator
  • Created beings cannot bring things into existence out of nothing
  • God created time in creating movement in the universe. 
  • The story of the six days of creation is a metaphor which helps human imagination. 
  • Augustine sometimes interprets the “beginning”' (in principio) of Gen. 1.1 as a temporal beginning
  • but following an established tradition, he also takes it to refer to the Word or the Son of God (John 1.1-3): “In this beginning, God, you made heaven and earth, in your Word, in your Son, in your power, in your wisdom, in your truth” (Conf. 11.9.11).
Cambridge Collections Online

Alfonsine Tables and Arabic names of stars

Alfonso X of Castile
Many Spanish/Latin transliterations of Arabic star names were given in the Alfonsine tables compiled during the Crusader period in Toledo in 1252. This work is a significant cultural bridge between Islamic Astronomy carrying on Greco-Roman traditions, Jewish scientists active in Caliphate of Cordoba and Christian world in Europe.

Alfonsine Tables are an example of the multicultural and multilingual environment that prevailed in early Medieval Spain. At the time of the Crusades it was an important peaceful meeting ground for Christian, Jewish and Islamic cultures.

The Castilian tradition carries on also today as the majority of the bright stars in the northern sky have Arabic names even the cultural and scientific prominence of the Islamic world has markedly declined from the heydays of the past.

[Alfonso X of Castile (1221 – 1284) also called Alfonso the Wise] assembled a team of scholars, known as the Toledo School of Translators, who among other translating tasks, were commanded to produce new tables that updated the Tables of Toledo.

The new tables were based on earlier astronomical works and observations by Islamic astronomers, adding observations by astronomers Alfonso had gathered in Toledo, among them several Jewish scholars, like Yehuda ben Moshe and Isaac ibn Sid. He also brought Aben Raghel y Alquibicio and Aben Musio y Mohamat, from Seville, Joseph Aben Alí and Jacobo Abenvena, from Córdoba, and fifty more from Gascony and Paris.

The instructions for the Alfonsine tables were originally written in Castilian Spanish. The first printed edition of the Alfonsine tables appeared in 1483, and a second edition in 1491. Georg Purbach used the Alfonsine tables for his book, Theoricae novae planetarum (New Theory of the Planets). Nicolaus Copernicus used the second edition in his work. One use of these and similar astronomical tables was to calculate ephemerides, which were in turn used by astrologers to cast horoscopes.

Arabic star names in Ursa Major

Ursa Major's stars. Book plate by Sydney Hall (1842 – 1922)
The Latin name of the constellation Ursa Major means the Great Bear. However, there is a rather sad Arabic tradition according to which the constellation of the Big Dipper is actually a funeral procession in which the four stars of the dipper form the bier, kubra, and the three stars of the handle are mourners following the coffin banat na'ash al kubra. The nightly slow and solemn movement of the constellation around the pole may have contributed to this association. (ref)

Despite of the tradition of funeral procession five of the Arabic names refer to locations on the body of the Greater Bear. (The Smaller Bear is Ursa Minor with Polaris). Only the names of the two stars at the end of the bear's tail refer to the funeral procession.

Ursa Major constellation

1. Dubhe
The back of the Greater Bear ظهر الدب الاكبر‎ żahr ad-dubb al-akbar

2. Merak
The loins المراق al-maraqq

3. Phecda
The tight of the Bear e فخذ الدب "fakhð ad-dubb

4. Megrez
The base (of the tail) المغرز‎ al-maghriz

5. Alioth
Fat tail of a sheep آليات alyat

6. Mizar and Alcor
Waistband or girdle مئزر mīzar
Alcor of uncertain origin has the Arabic name سها suha "the neglected one"

Mizar and Alcor, Horse and Rider
Photo: ESO Online Digitized Sky Survey
The Arabs in the desert regarded it as a test of penetrating vision; and they were accustomed to oppose suhel to suha (Canopus to Alcor) as occupying respectively the highest and lowest posts in the celestial hierarchy.  So that

vidit alcor at non lunam plenam

(Latin for "he saw Alcor, but not the full moon")  came to be a proverbial description of one keenly alive to trifles, but dull of apprehension for broad facts.

al sahja was the rhythmical form of the usual Suha; and it appears as al khawwar, the Faint One, in an interesting list of Arabic star-names, published in Popular Astronomy for January, 1895, by Professor Robert H. West, of the Syrian Protestant College at Beirut.

The 14th century Arabian lexicographer Al Firuzabadi called it Our Riddle, and Al Sadak, the Test,—correctly Saidak, True; while the 13th century Persian astronomical writer Al Kazwini said that "people tested their eyesight by this star."

Humboldt wrote of it as being seen with difficulty, and Arago similarly alluded to it; but some now consider it brighter than formerly and no longer the difficult object that it was, even in the clear sky of the Desert; or as having increased in angular distance from Mizar.

7. Alkaid
Leader of the Daughters of the Bier قائد بنات نعش qā'id bināt naʿsh
The well-known Arabic word al qaida is from another root with basic meaning "to sit". (ref)

Detailed information about star names can be found in the excellent Constellations of words - stars.

Wednesday, May 2, 2012

Cosmic Godless Inclusion Zone (CGsIZ)

The Cosmic Godless Inclusion Zone (CGsIZ) invites with open arms all those who question or deny the existence or influence of any supernatural being on the real physical world. Perhaps such creations of human imagination have some role in social life and for individuals offering escape to those having problems in facing the hard facts of life.

Questioning or denying the existence of God is considered in this inclusion zone to be soooo cool and modern - and most importantly, the only proper realm of a truly scientific mind free from superstitions of the past.

How Science works?
The key in the scientific cosmic godless inclusion zone definition is the way how Science works.

Different branches of Science set the playground in which they attempt to solve specific questions and to offer explanations and predictions. The ground rules of the scientific game, regardless of what is being studied from Cosmology to Astrobiology to Mathematics or Astrophysics ... are set so that it is possible to verify the theory or hypothesis.

Verification methods vary greatly from purely logical to highly experimental but the axiomatic ground rule of the game is that science seeks answers to questions it can solve now or in the future.

The question "Does God exist?" is not in the realm of science and should not be considered as such.

Modern science does not accept any kind of deus ex machina i.e. divine intervention or influence of invisible spirits and personal powers as explanation to natural phenomena. In contrast to this, religions may and do explain phenomena in many different ways from traditional to innovative but this is not considered nor was ever in the past considered science.

It is true that ancient science was often permuted with Astrological beliefs and the influential power in stars on our existence. But at the same time there were attempts to categorize these traditions and to rationally explain these sky powers, leading scientific theories of those days. A prime example of this is the famed Ptolemy of Alexandria (90-168 AD) and his Tetrabiblos.

Today's scholars consider such attempts pre-scientific which is as good definition as any but Tetrabiblos shows the basic attempt of human reasoning that has since evolved into modern scientific inquiry.

How God works?
The fundamental error in both Atheism and Creationism - two sides of the same coin - is an assumption that religious people can by faith explain natural phenomena for example on the basis of the Bible or Koran.

Materialist gives an explanation that needs no supernatural intervention (what kind of intervention would that be exactly?)

Religious person offers Intelligent Design so obvious in the Nature as proff of God's supernatural intervention (how God works exactly?)

Is God needed?
For example, Stephen Hawking (1942) tries in his recent books to figure out whether or not God is necessary for understanding the existence of cosmos - a perfectly welcome theoretical and philosophical line of inquiry of highest Academic credentials in the Cosmic Godless Inclusion Zone (CGIZ).

However, there is a major hitch on the way of answering such a question.

For in order to determine is God needed or is everything product of impersonate processes according to laws of nature nobody has set, Stephen Hawking needs to know how God works. What exactly is the observable mechanism the invisible supernatural ONE uses in order to interact with His creation?

How does God feed the raven, as the Bible says:
He giveth to the beast his food and to the young ravens which cry.
Ps 147:9

Only when Hawking or others considering is God needed are able either to pinpoint the finger of God, explain the acts of God in nature for an affirmative answer or to explain things satisfactorily without obvious intervention by God for negative answer, is his answer a theory that can be verified in the real world.

As for today, nobody - and I repeat not a single human being - knows how God works.

Do we see God in action?
The same fundamental error affects rationalistic creationists (not so rarely former atheists) in their God Inclusion Zone (CGdIZ).  It is taken as an axiomatic fact that somehow we are able to see how God works in nature.

This is, of course, utter nonsense as the real God of Israel is hidden and seeing Him as He is would be lethal to humans.

Creationism mixes the fact that we are able to see the results of God's work in nature, the majesty and wisdom of what He has done and which is self-evident, with the claim that we can see how God works, His fundamental relation to the creation. 

Tuesday, May 1, 2012

Cosmic God Exclusion Zone (CGdEZ)

There are those who would exclude God from all scientific discussions on the Cosmos.

I hereby declare all such attempts to establish a Cosmic God Exclusion Zone (CGdEZ) null and void by the authority given to me - and you - by the sole holder of copyright on Creation.

Suggesting and trying to maintain such a zone is like having an international conference on the art of Picasso with strict order to all participants not to utter a single word about the artist himself.

© 2012 God of Israel

Sirius worship in various religions

Human religions are very complex expressions of culture, history, and world view but have one thing in common - the importance of stars in the night sky.

For modern citizens of cities with massive light pollution the awesome effect of a dark night and sparkling brilliant stars is not immediately clear. Religious minds tend to pick targets for worship and apparently in most if not all pre-modern cultures star worship has been quite significant in one way or another.

Sirius not in the Bible
As far as I know, Sirius is not specifically mentioned in the Bible. In modern Hebrew it is called אברק avreq "shining".

The first chapter of the Bible is a veritable slaughterhouse of gods for God alone is the creator of everything, including Sun, Moon and stars. Elsewhere in the Bible there are passages with strong condemnation of pagan star worship, especially in Jeremiah speaking against the Babylonian cult Queen of the Heaven (Ishtar, Venus).

But let us keep in mind that the Scriptures also shows understanding of the meaning of stars to humanity to the point where Daniel was made the head of Chaldean astrologists. Even more so, the birth of the Son of God was marked by the appearance of the Star of Bethlehem as a beautiful sign the wise men from the East interpreted meaning the birth of a great king in Palestine.

Sirius worship among nations
What it means when we modern people say that a star represents a divinity? What was Mars for the ancient Romans or Ishtar for the ancient Babylonians but a physical presence of the divinity in the night sky? Human religious mind hardly confines Mars to the Red planet or hindu god Rudra to Sirius, but somehow the heavenly body is a mighty Sign of divine presence. (We can study this mental construct with authentic material when analysing the oratio to Sun by emperor Julian the Apostate).

Since so many different cultures connect Sirius with dog I suspect that there may be a prehistoric substratum to this association perhaps reaching even Neolithic when we have the first evidence of domesticated dogs joining human camp fires.

Traces of common memes from the distant past in different civilizations ... perhaps!

Ancient Egypt
As the brightest star of the night and visible in both hemispheres Sirius is known to all nations. It has religious and also practical significance as a calendar for ancient Egyptians.

The Sothic cycle or Canicular period is a period of 1,461 ancient Egyptian years (of 365 days each) or 1,460 Julian years (averaging 365.25 days each). During a Sothic cycle, the 365-day year loses enough time that the start of the year once again coincides with the heliacal rising of the star Sirius (the Latinized name for Greek Σείριος, a star called Sopdet by the Egyptians, in Greek transcribed as Sothis; a single year between heliacal risings of Sothis is a Sothic year). This rising occurred within a month or so of the beginning of the Nile flood, and was a matter of primary importance to this agricultural society. It is believed that Ancient Egyptians followed both a 365-day civil calendar and a lunar religious calendar.

At the Temple of Hathor in Dendera there is a painting in which the goddess of Nile flooding (arrows) Satet has drawn her arrow at Hathor associated with Sirius. (These few notes are just the tip of an ice berg in the complex and deep relationship of ancient Egyptians with the star they called Sodpet).

Ancient Greece and Rome
The archaic Greek name for Sirius, Seirios, could well be derived from the major Egyptian god Osiris as the Osiris-Isis-Horus myth is closely related to the agricultural seasons, the cycle of nature dying and rising again with the Nile.

It was classically depicted as Orion's dog. The Ancient Greeks thought that Sirius's emanations could affect dogs adversely, making them behave abnormally during the "dog days," the hottest days of the summer. The Romans knew these days as dies caniculares, and the star Sirius was called Canicula, "little dog." The excessive panting of dogs in hot weather was thought to place them at risk of desiccation and disease. In extreme cases, a foaming dog might have rabies, which could infect and kill humans whom they had bitten. Homer, in the Iliad, describes the approach of Achilles toward Troy in these words:

Sirius rises late in the dark, liquid sky
On summer nights, star of stars,
Orion's Dog they call it, brightest
Of all, but an evil portent, bringing heat
And fevers to suffering humanity

Pre-islamic Arabia
Sirius is mentioned in Surah, An-Najm ("The Star"), of the Qur'an, where it is given the name الشِّعْرَى (al-shiʿraa.) The verse is: "وأنَّهُ هُوَ رَبُّ الشِّعْرَى", "That He is the Lord of Sirius (the Mighty Star)." (An-Najm:49)  Ibn Kathir said in his commentary "Ibn 'Abbas, Mujahid, Qatada and Ibn Zayd said about Ash-Shi`ra that it is the bright star, named Mirzam Al-Jawza' (Sirius), which a group of Arabs used to worship

Ancient Iran
In Iranian mythology, especially in Persian mythology and in zoroastrianism, the ancient religion of Persia, Sirius appears as Tishtrya and is revered as a divinity. Beside passages in the sacred texts of the Avesta, the Avestan language Tishtrya followed by the version Tir in Middle and New Persian is also depicted in the Persianepic Shahnameh of Ferdowsi. Due to the concept of the yazatas, powers which are "worthy of worship", Tishtrya is a divinity of rain and fertility and an antagonist ofapaosha, the demon of drought. In this struggle, Tishtrya is beautifully depicted as a white horse.

India today
In Sanskrit Mrgavyadha (Deer hunter) Sirius represents the god of wind, storm and hunt Rudra (Shiva). Since the worship of Shiva continues today in India there it is the possibility to ask living people what significance Sirius (and other stars in the night sky) have on their lives.

In the Tamil related language Malayalam Sirius is called Makarajyotii and is associated with the ongoing pilgrimage to Sabarimala.

Sabarimala is a Hindu pilgrimage center located in the Western Ghat mountain ranges of Pathanamthitta District in Kerala. It is the largest annual pilgrimage in world with an estimated 45–50 million devotees visiting every year. Sabarimala is believed to be the place where the Hindu God Ayyappan meditated after killing the powerful demoness, Mahishi. Ayyappan's temple is situated here amidst 18 hills. The temple is situated on a hilltop at an altitude of 468 m (1535 ft) above mean sea level, and is surrounded by mountains and dense forests.

Temples exist in each of the hills surrounding Sabarimala. While functional and intact temples exist at many places in the surrounding areas like Nilackal, Kalaketi, and Karimala, remnants of old temples survive to this day on remaining hills.

Sabarimala is linked to Hindu pilgrimage, predominantly for men of all ages. Women between the ages of 10 and 50 are not allowed to enter the temple, since the story attributed to Ayyappa prohibits the entry of the women in the menstrual age group. This is because Ayyappan is a Bramachari (Celibate).

The temple is open for worship only during the days of Mandalapooja (approximately November 15 to December 26), Makaravilakku (January 14- "Makara Sankranti") and Vishu (April 14), and the first six days of each Malayalam month.

Ancient Scandinavians
In Norse tradition Sirius is called Lokabrenna ("Loki's torch"). Loki is in some myths a god and in others a  giant.

Loki's relation with the gods varies by source. Loki sometimes assists the gods and sometimes causes problems for them. Loki is a shape shifter and in separate incidents he appears in the form of a salmon, mare, seal, a fly, and possibly an elderly woman. Loki's positive relations with the gods end with his role in engineering the death of the god Baldr. Loki is eventually bound by the gods with the entrails of one of his sons.

It is interesting that Loki was also projected to the sky and associated with Sirius. We may assume that the star Sirius was important aid in navigation for the seagoing Vikings who even were able to cross the Atlantic in their slender boats. Loki was not an easy character in dangerous trips as he was known as a trickster god.

Native Americans
Sirius has religious meaning for the Cherokees who paired the bright white star with the reddish Antares as dog-star guardians of either end of the "Path of Souls". Other tribes also associated Sirius with dogs, wolfs or coyotes, and so did the Inuit of Alaska.

Ancient Far East
Chinese called Sirius the star of the "celestial wolf" in the Mansion of Jǐng. However, I do not know was there any religious meaning or cult of Sirius in ancient China, Korea or Japan.

Sirius B - a White dwarf

Hubble Space Telescope image of Sirius A
along with its faint stellar companion, Sirius B
Hubble gallery ESA

The brightest star in the night sky is the Dog star Sirius near the great hunter Orion. Sirius is one of the closest stars to us at the distance of mere 8.6 ly. Astronomers tell that this fabulous beacon of the night (Σείριος Seirios) is actually a binary star including Sirius A and an almost invisible, tiny but very heavy companion white dwarf Sirius B.

In 1844 German astronomer Friedrich Bessel deduced from changes in the proper motion of Sirius that it had an unseen companion. Nearly two decades later, on January 31, 1862, American telescope-maker and astronomer Alvan Graham Clark first observed the faint companion, which is now called Sirius B, or affectionately "the Pup". This happened during testing of a 18.5-inch (470 mm) aperture great refractor telescope for Dearborn Observatory, which was the largest refracting telescope lens in existence at the time, and the largest telescope in America

The pair started life about 300 million years ago as a heavenly pair of bright blue stars happily burning hydrogen to helium as main sequence stars do. But alas! Old age does not come alone... As the internal fuel of Sirius B got burned out about 120 million years ago it began to swell into a huge Red giant. It then collapsed and shrank into the tiny hot ball of carbon and oxygen. Although it is only the diameter of Earth it  has the amazing mass of almost one Sun packed very densely. The disintegration probably is the source of unusual iron astronomers have noted on the surface of Sirius.

White dwarf
Wikipedia teaches us about white dwarfs (introduction for your convenience here with my emphasis - please, read the entire article from here)

A white dwarf, also called a degenerate dwarf, is a small star composed mostly of electron-degenerate matter.

They are very dense; a white dwarf's mass is comparable to that of the Sun and its volume is comparable to that of the Earth. Its faint luminosity comes from the emission of stored thermal energy.  In January 2009, the Research Consortium on Nearby Stars project counted eight white dwarfs among the hundred star systems nearest the Sun. The unusual faintness of white dwarfs was first recognized in 1910 by Henry Norris Russell, Edward Charles Pickering, and Williamina Fleming the name white dwarf was coined by Willem Luyten in 1922.

White dwarfs are thought to be the final evolutionary state of all stars whose mass is not high enough to become a neutron star—over 97% of the stars in our galaxy.

After the hydrogen–fusing lifetime of a main-sequence star of low or medium mass ends, it will
expand to a red giant which fuses helium to carbon and oxygen in its core by the triple-alpha process.

If a red giant has insufficient mass to generate the core temperatures required to fuse carbon, around 1 billion K, an inert mass of carbon and oxygen will build up at its center.

After shedding its outer layers to form a planetary nebula, it will leave behind this core, which forms the remnant white dwarf. Usually, therefore, white dwarfs are composed of carbon and oxygen.

If the mass of the progenitor is above 8 solar masses but below 10.5 solar masses, the core temperature suffices to fuse carbon but not neon, in which case an oxygen-neon–magnesium white dwarf may be formed.

Also, some helium white dwarfs appear to have been formed by mass loss in binary systems.

The material in a white dwarf no longer undergoes fusion reactions, so the star has no source of energy, nor is it supported by the heat generated by fusion against gravitational collapse. It is supported only by electron degeneracy pressure, causing it to be extremely dense.

The physics of degeneracy yields a maximum mass for a non-rotating white dwarf, the Chandrasekhar limit—approximately 1.4 solar masses—beyond which it cannot be supported by electron degeneracy pressure.

Supernova SN 1006.
A carbon-oxygen white dwarf that approaches this mass limit, typically by mass transfer from a companion star, may explode as a Type Ia supernova via a process known as carbon detonation. (SN 1006 is thought to be a famous example.)

A white dwarf is very hot when it is formed, but since it has no source of energy, it will gradually radiate away its energy and cool down. This means that its radiation, which initially has a high color temperature, will lessen and redden with time. Over a very long time, a white dwarf will cool to temperatures at which it will no longer emit significant heat or light, and it will become a cold black dwarf.

However, since no white dwarf can be older than the age of the Universe (approximately 13.7 billion years), even the oldest white dwarfs still radiate at temperatures of a few thousand kelvins, and no black dwarfs are thought to exist yet.

Parsec and the cosmic patience of God of Israel (2)

Hipparcos satellite testing
Hipparcos (an acronym for "High precision parallax collecting satellite") was a scientific mission of the European Space Agency (ESA), launched in 1989 and operated between 1989 and 1993. It was the first space experiment devoted to precision astrometry, the accurate measurement of the positions of celestial objects on the sky. This permits the accurate determination of proper motions and parallaxes of stars, allowing a determination of their distance and tangential velocity. When combined with radial velocity measurements from spectroscopy, this fixes all six quantities needed to determine the motion of the star.

The Hipparcos Catalogue, a high-precision catalogue of more than 100,000 stars, was published in 1997. The lower precision Tycho Catalogue of more than a million stars was published at the same time, while the enhanced Tycho-2 Catalogue of 2.5 million stars was published in 2000.

In the Book of Jeremiah there is a text of cosmic dimensions where God of Israel is thinking aloud something truly scary. He says - through prophet Jeremiah - that under certain conditions God may completely and finally abandon His chosen people Israel and they will never more be His nation.

But this shall be the covenant that I will make with the house of Israel; After those days, saith the LORD,
I will put my law in their inward parts, and write it in their hearts; and will be their God, and they shall be my people. And they shall teach no more every man his neighbour, and every man his brother, saying, Know the LORD: for they shall all know me, from the least of them unto the greatest of them, saith the LORD: for I will forgive their iniquity, and I will remember their sin no more.
Thus saith the LORD, which giveth the sun for a light by day, and the ordinances of the moon and of the stars for a light by night, which divideth the sea when the waves thereof roar; The LORD of hosts is his name:

If those ordinances depart from before me, saith the LORD, then the seed of Israel also shall cease from being a nation before me for ever. 

Thus saith the LORD; If heaven above can be measured, and the foundations of the earth searched out beneath, I will also cast off all the seed of Israel for all that they have done, saith the LORD.
Jeremiah 31:33-37 KJ

The prophecy contains what must certainly looked like an impossible condition for the ancients assuring the people of Israel that they can break even this covenant - the writing of the law in their hearts - God will never abandon them.

Unfortunately, today heaven above can be measured, and the foundations of the earth searched out.

This makes this word of God of Israel through prophet Jeremiah both relevant and rather scary. Even God's patience has limits - measured in parsec. The Hippocrates and Gaia projects are currently on way to use space-based telescopes to measure as accurately as possible the heaven above.


Measuring the heaven above
The parsec is equal to the length of the adjacent side of an imaginary right triangle in space. The two dimensions on which this triangle is based are the angle (which is defined as 1 arcsecond), and the opposite side (which is defined as 1 astronomical unit, which is the distance from the Earth to the Sun). Using these two measurements, along with the rules of trigonometry, the length of the adjacent side (the parsec) can be found.

One of the oldest methods for astronomers to calculate the distance to a star was to record the difference in angle between two measurements of the position of the star in the sky.

The first measurement was taken from the Earth on one side of the Sun, and the second was taken half a year later when the Earth was on the opposite side of the Sun. The distance between the two positions of the Earth for the measurements was known to be twice the distance between the Earth and the Sun. The difference in angle between the two measurements was known to be twice the parallax angle, which is formed by lines from the Sun and Earth to the star at the vertex. Then the distance to the star could be calculated using trigonometry.

The first successful direct measurements of an object at interstellar distances were undertaken by German astronomer Friedrich Wilhelm Bessel in 1838, who used this approach to calculate the distance of 61 Cygni.

The parallax method is the fundamental calibration step for distance determination in astrophysics; however, the accuracy of ground-based telescope measurements of parallax angle is limited to about 0.01 arcseconds, and thus to stars no more than 100 pc distant. This is because the Earth’s atmosphere limits the sharpness of a star's image.

Space-based telescopes are not limited by this effect and can accurately measure distances to objects beyond the limit of ground-based observations.

Between 1989 and 1993, the Hipparcos satellite, launched by the European Space Agency (ESA), measured parallaxes for about 100,000 stars with an astrometric precision of about 0.97 milliarcseconds, and obtained accurate measurements for stellar distances of stars up to 1,000 pc away.

NASA's FAME satellite was to have been launched in 2004, to measure parallaxes for about 40 million stars with sufficient precision to measure stellar distances of up to 2,000 pc. However, the mission's funding was withdrawn by NASA in January 2002.

ESA's Gaia satellite, due to be launched in late 2012, is intended to measure one billion stellar distances to within 20 microarcseconds, producing errors of 10% in measurements as far as the Galactic Center, about 8,000 pc away in the constellation of Sagittarius.