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Lyra: The Harp of Heaven

Friday, May 29, 2015 Category : , , , Off

Lyra:
The Harp of Heaven


For a little constellation, Lyra has big ideas! It has the commanding star of the summer sky, Vega, fifth brightest of all stars. It has a wondrous deep-sky object, M57, the Ring Nebula. It has its own meteor shower, the Lyrids which can be observed between April 20-22 each year. It has its own class of variable star, called the RR Lyrae stars. And Lyra is also the location for another fascinating variable, b Lyrae, a mysterious system that is an eclipsing binary with a possible black hole as one of its components. Epsilon Lyrae is a favorite telescopic object. It is the “double-double,” discernible to those with exceptional eyesight as a pair of stars; and with a small telescope, each can be resolved into a double, as well. A lesser pair of double stars also shines in Lyra, although the components are not quite so bright nor so closely spaced. They are S 2470 and S 2474.


Lyra is a small constellation, quite easily identified as it appears to consist of an equilateral triangle attached to a parallelogram. The brightest star, Vega, is one of the three stars, along with Deneb and Altair, that form the asterism of the Summer Triangle.

Photo by Conrad Jung.

The wonderful Ring Nebula, M57, can be found between Gamma- and Beta-Lyra, the two stars that form the side of the parallelogram opposite Vega.

Because of their circular appearance such rings are also called planetary nebula. They are very large, as much as a thousand times as large as our solar system. The very hot central star is responsible for the luminescence of the nebula.
Photo by Jim Scala

 

Lyra is also prominent in the history of astronomy. Vega was the first star to pose for its photograph, taken by Bond and Whipple a hundred-fifty years ago on July 16, 1850, at Harvard College Observatory. Vega was also among the first stars whose parallax was accurately determined, by F. G. Wilhelm Struve, father of the noted Otto Struve. Vega's role in future history is assured, as well, for it has been calculated that in something like 12,000 years, owing to precession of the equinoxes, Vega will assume the title of North Star.

Incidentally, the name Vega is properly pronounced as if it were spelled Wega, for it derives from the Arabic, meaning “Swooping Eagle of the Desert.”

Classical mythology links the lyre and the tortoise in the story of Mercury, who found a tortoise shell and toyed with it. He noticed the resonance when he tapped the shell, which gave him the idea to drill holes along opposite sides and lace these with linen threads. He used one each for the nine Muses. So was the lyre invented; and Mercury played enchanting music. On Olympus, home of the gods, Apollo beseeched Mercury to teach him also to play, and Mercury traded the lyre to Apollo for his caduceus, the staff that brought prosperity and wealth to its owner and gave him the power to fly. Mercury then became the swift messenger of the gods, enabled by the caduceus and his winged sandals. Apollo later gave the lyre to his son, Orpheus, who learned to play with such talent that he would soothe the wild beasts. He could charm even Pluto, king of the realm of the dead. But that is another story.

After the death of Orpheus (in that other story), Jupiter placed the lyre in the heavens, where it is high overhead, a jewel in the summer evening skies

Constellation of Lyra

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History[edit]

In the past, Lyra was often represented on star maps as a vulture or an eagle [A sacred Bird] carrying a lyre, either enclosed in its wings, or in its beak. It was sometimes referred to as Aquila Cadens or Vultur Cadens (falling eagle or falling vulture).[11] This historical association is preserved in the name of its brightest star, Vega, which is derived from an Arabic term meaning "swooping eagle."[12]

Vega is the Eye of the Eagle [Lyra] [Horus is action, Landing Eagle]

Mythology[edit]

Lyra can be seen on the right of this c. 1825 star map from Urania's Mirror.
In Greek mythology, Lyra was associated with the myth of Orpheus, the musician who was killed by the Bacchantes. After his death, his lyre was thrown into the river; Zeus sent an eagle to retrieve the lyre, and ordered both of them to be placed in the sky.[citation needed] In Wales, Lyra is known as King Arthur's Harp (Talyn Arthur), and King David's harp [2]. The Persian Hafiz called it the Lyre of Zurah.[3] It has been called the Manger of the Infant Saviour, Praesepe Salvatoris [4].
In Japanese mythology, originating from the Chinese Qixi festival, Vega is sometimes called Tanabata (or Orihime), a celestial princess or goddess. She falls in love with a mortal, Kengyu (or Hikoboshi), represented by the star Altair. But when Tanabata’s father finds out, he is enraged and forbids her to see this mere mortal. Thus the two lovers are placed in the sky, where they are separated by the Celestial River, known to us as Milky Way. Yet the sky gods are kind. Each year, on the 7th night of the 7th moon ( ~~SPRING EQUINOX], a bridge of magpies forms across the Celestial River, and the two lovers are reunited. Sometimes Kengyu’s annual trip across the Celestial River is treacherous, though, and he doesn’t make it. In that case, Tanabata’s tears form raindrops that fall over Japan.
Many Japanese celebrations of Tanabata are held in July, but sometimes they are held in August. If it rains, the raindrops are thought to be Tanabata’s tears because Kengyu could not meet her. Sometimes the meteors of the Perseid shower are said to be Tanabata’s tears.[13]

Equivalents in other astronomical systems[edit]

Vega and its surrounding stars are also treated as a constellation in other cultures.
In Australian Aboriginal astronomy, Lyra is known by the Boorong people in Victoria as the Malleefowl constellation.[14]
Lyra was known as Urcuchillay by the Incas and was worshipped as an animal deity.

Paremhat, 7th Lunar month = March 10 to April 8

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Paremhat (Coptic: Ⲡⲁⲣⲉⲙϩⲁⲧ[pronunciation?]), also known as Baramhat, is the seventh month of the Coptic calendar. It lies between March 10 and April 8 of the Gregorian calendar.
The Coptic name Paremhat comes from the Egyptian name of the month, pa-en-Amenhotep, "month of Amenhotep I", who was deified in the polytheistic Ancient Egyptian religion following his reign (ca. 1500 BC) – the month formerly known as Rekeh-nedjes being renamed in his honor.
Paremhat is also the third month of the Season of Proyet (Growth and Emergence) in Ancient Egypt, where the Nile floods recede and the crops start to grow throughout the land of Egypt.

Akhet, the beginning of season, presided by Thoth (T[dh]ut)

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N27
Akhet (horizon)
in hieroglyphs
The Egyptian language word Akhet is both a hieroglyph and an Ancient Egyptian season.
The two uses for akhet:
  • In ancient Egyptian, the place where the sun rises and sets; often translated as "horizon" or "mountain of light". It is included in names like "Akhet Khufu" (Ancient Egyptian name for the Great Pyramid) and Akhetaten. Betrò's book names the hieroglyph: 'Mountain with the Rising Sun', and the hieroglyph is used as an ideogram for"horizon".[1] In ancient Egyptian religion, the Pylon mirrored the hieroglyph for 'horizon' - akhet, which also was associated with recreation and rebirth.
M8
Aa1 t		ra
Akhet (season)
in hieroglyphs
  • The "Akhet season" ran approximately from mid-July to mid-November in Ancient Egypt, and was followed byPeret and Shemu.[2] It is the first of three seasons of the ancient Egyptian calendar—the inundation season. This was the time of the Egyptian calendar year when the Nile waters flooded farmland and brought much nutrients to the tilled soil.
    The Year
    The world's 365 day year is a result of the Egyptian three seasons, 120 days, three times, and an annual New Year 5-day festival.
Months
No.Seasonal NamesMiddle KingdomNew KingdomGreekCopticEgyptian Arabic
Latin scriptGreek script[7]Latin scriptArabic script
1First of AkhetTekhD[t]hwt [TUT]ThothΘώθ [TUT]ThoutToutتوت
2Second of AkhetMenhetPa-n-ip.tPhaophiΦαωφί/ΦαῶφιPaopiBabaبابه
3Third of AkhetḤwt-ḥwrḤwt-ḥwrAthyrἈθύρHathorHatourهاتور
4Fourth of AkhetKa-ḥr-kaKa-ḥr-kaChoiakΧοιάκ/ΧοίακKoiakKiahk(كياك (كيهك
5First of PeretSf-bdtTa-'bTybiΤυβί/ΤῦβιTobiToubaطوبه
6Second of PeretRekh werMḫyrMechirΜεχίρ/ΜεχείρMeshirAmshirأمشير
7Third of PeretRekh nedsPa-n-amn-htp.wPhamenothΦαμενώθParemhatBaramhatبرمهات
8Fourth of PeretRenwetPa-n-rnn.tPharmouthiΦαρμουθί/ΦαρμοῦθιParemoudeBaramoudaبرموده
9First of ShemuHnswPa-n-ḫns.wPachonΠαχώνPashonsBashansبشنس
10Second ofShemuHnt-htjPa-n-in.tPayniΠαϋνί/ΠαῦνιPaoniBa'ounaبئونه
11Third of ShemuIpt-hmtIpipEpiphiἘπιφί/ἘπείφEpipAbibأبيب
12Fourth of ShemuWep-renpetMsw-r'MesoreΜεσορήMesoriMesraمسرا

The Hebrew or Jewish calendar

Tuesday, March 24, 2015 Category : Off

Jewish calendar, showing Adar II between 1927 and 1948
Today
The Hebrew or Jewish calendar (הַלּוּחַ הָעִבְרִי, ha'luach ha'ivri) is a lunisolar calendar used today predominantly for Jewish religious observances. It determines the dates for Jewish holidays and the appropriate public reading of Torah portions, yahrzeits (dates to commemorate the death of a relative), and daily Psalm readings, among many ceremonial uses. In Israel, it is used for religious purposes, provides a time frame for agriculture and is an official calendar for civil purposes, although the latter usage has been steadily declining in favor of the Gregorian calendar.
The present Hebrew calendar is the product of evolution, including a Babylonian influence. Until the Tannaitic period (approximately 10–220 CE) the calendar employed a new crescent moon, with an additional month normally added every two or three years to correct for the difference between twelve lunar months and the solar year. When to add it was based on observation of natural agriculture-related events.[1] Through the Amoraic period (200–500 CE) and into the Geonic period, this system was gradually displaced by the mathematical rules used today. The principles and rules were fully codified by Maimonides in the Mishneh Torah in the 12th century. Maimonides' work also replaced counting "years since the destruction of the Temple" with the modern creation-era Anno Mundi.
The Hebrew lunar year is about eleven days shorter than the solar cycle and uses the 19-year Metonic cycle to bring it into line with the solar cycle, with the addition of an intercalary month every two or three years, for a total of seven times per 19 years. Even with this intercalation, the average Hebrew calendar year is longer by about 6 minutes and 2525/57 seconds than the current mean solar year, so that every 224 years, the Hebrew calendar will fall a day behind the current mean solar year; and about every 231 years it will fall a day behind the Gregorian calendar year.
The era used since the middle ages is the Anno Mundi epoch (Latin for "in the year of the world"; Hebrew: לבריאת העולם, "from the creation of the world"). As with Anno Domini (A.D. or AD), the words or abbreviation for Anno Mundi (A.M. or AM) for the era should properly precede the date rather than follow it, although this is no longer always followed.
AM 5774 began at sunset on 4 September 2013 and ended on 24 September 2014. AM 5775 began at sunset on 24 September 2014 and ends at sunset on 13 September 2015. AM 5776 begins at sunset on 13 September 2015 and ends at sunset on 2 October 2016.[2]

Components[edit]

Day and hours[edit]

Further information: Zmanim
The Jewish day is of no fixed length. The Jewish day is modeled on the reference to "...there was evening and there was morning..."[3] in the Creation account in the first chapter of Genesis. Based on the classic Rabbinic interpretation of this text, a day in the Rabbinic Hebrew calendar runs from sunset (start of "the evening") to the next sunset. The time between sunset and the time when three stars are visible (known as 'tzait ha'kochavim') is known as 'bein hashmashot' and for some uses is debated as what day it is. One complicating factor is that there is no clear cut sunrise or sunset time at the extreme latitudes during certain seasons. At higher latitudes in summer, when the sun does not sink below the horizon, a day is counted from midday to midday, and in the winter, when the sun does not rise above the horizon, from midnight to midnight.
There is no clock in the Jewish scheme, so that a civil clock is used. Though the civil clock, including the one in use in Israel, incorporates local adoptions of various conventions such as time zones, standard times and daylight saving, these have no place in the Jewish scheme. The civil clock is used only as a reference point – in expressions such as: "Shabbat starts at ...". The steady progression of sunset around the world and seasonal changes results in gradual civil time changes from one day to the next based on observable astronomical phenomena (the sunset) and not on man-made laws and conventions.
In Judaism, an hour is defined as 1/12 of the time from sunrise to sunset, so during the winter, an hour can be much less than 60 minutes, and during the summer, it can be much more than 60 minutes. A Judaic hour is known as a 'sha'ah z'manit' which means a timely hour.
Instead of the international date line convention, there are varying opinions as to where the day changes. One opinion uses the antimeridian ofJerusalem. (Jerusalem is 35°13’ east of the prime meridian, so the antimeridian is at 144°47' W, passing through eastern Alaska.) Other opinions exist as well.[4][5]
Every hour is divided into 1080 halakim (singular: helek) or parts. A part is 3⅓ seconds or 1/18 minute. The ultimate ancestor of the helek was a small Babylonian time period called a barleycorn, itself equal to 1/72 of a Babylonian time degree (1° of celestial rotation).[6] Actually, the barleycorn or shewas the name applied to the smallest units of all Babylonian measurements, whether of length, area, volume, weight, angle, or time.
The weekdays start with Sunday (day 1, or Yom Rishon) and proceed to Saturday (day 7), Shabbat. Since some calculations use division, a remainder of 0 signifies Saturday.
While calculations of days, months and years are based on fixed hours equal to 1/24 of a day, the beginning of each halachic day is based on the local time of sunset. The end of the Shabbat and other Jewish holidays is based on nightfall (Tzeth haKochabim) which occurs some amount of time, typically 42 to 72 minutes, after sunset. According to Maimonides, nightfall occurs when three medium-sized stars become visible after sunset. By the 17th century this had become three second-magnitude stars. The modern definition is when the center of the sun is 7° below the geometric (airless) horizon, somewhat later than civil twilight at 6°. The beginning of the daytime portion of each day is determined both by dawn and sunrise. Mosthalachic times are based on some combination of these four times and vary from day to day throughout the year and also vary significantly depending on location. The daytime hours are often divided into Sha`oth Zemaniyoth or "Halachic hours" by taking the time between sunrise and sunset or between dawn and nightfall and dividing it into 12 equal hours. The nighttime hours are similarly divided into 12 equal portions, albeit a different amount of time than the "hours" of the daytime. The earliest and latest times for Jewish services, the latest time to eat Chametz on the day before Passover and many other rules are based on Sha`oth Zemaniyoth. For convenience, the modern day using Sha`oth Zemaniyoth is often discussed as if sunset were at 6:00pm, sunrise at 6:00am and each hour were equal to a fixed hour. For example, halachic noon may be after 1:00pm in some areas during daylight saving time. Within the Mishnah, however, the numbering of the hours starts with the "first" hour after the start of the day.[7]

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Anno Mundi

Sunday, February 8, 2015 Category : , Off

A Jewish gravestone using the Year After Creation[1] (Anno Mundi) chronology
Anno Mundi (Latin for "in the year of the world"; Hebrew: לבריאת העולם, "from the creation of the world"), abbreviated as AM or A.M., or Year After Creation,[1] is a calendar era based on the biblical accounts of the creation of the world and subsequent history. While numerous efforts have been made to determine the biblical date of Creation, yielding varying results, two in particular have established epochs for significant calendars, including one that is still in use today.
The Hebrew calendar epoch is based on twelfth-century Rabbinic estimates for the year of creation which are calculated from data obtained in the Hebrew Masoretic text.[2] This calendar is used within Jewish communities for religious and other purposes. The calendar's epoch, corresponding to the calculated date of the world's creation, is equivalent to sunset on the Julian proleptic calendar date 6 October 3761 BC, [Month of Thoth].[3] (In the Hebrew calendar, the day begins at sunset, not at midnight.) The new year begins at Rosh Hashanah(roughly in September); year AM 5775 began at sunset on 24 September 2014 (Gregorian).
The Byzantine calendar, used for over 1000 years in the Byzantine Empire and many Christian Orthodox countries and Eastern Orthodox Churches, based its epoch on seventh-century (or earlier) calculations from data found in the Septuagint text, a slightly earlier Greek translation of the Hebrew Bible that was made by Alexandrian Jews and adopted by Christians.[4] That calendar is actually the Julian calendar itself, except for the eastern-derived epoch of year counting in place of the western AD/BC epoch, and a different new year's date, 1 September. It proposed that the creation occurred 5509 years before the Incarnation,[5] so its epoch is equivalent to 1 September 5509 BC on the Julian proleptic calendar.
While differences in Biblical interpretation or in calculation methodology can produce some differences in the creation date, most results fall relatively close to one of these two dominant models. The primary reason for the disparity seems to lie in which underlying Biblical text is chosen (roughly 5500 BC based on the Greek Septuagint text, about 3750 BC based on the Hebrew Masoretic text). Most of the 1,732-year difference resides in numerical discrepancies in the genealogies of the two versions of the Book of Genesis. Patriarchs from Adam to Terah, the father of Abraham, are said to be older by as much as 100 years or more when they begat their named son in the Greek Septuagint[6][7] than they were in the Latin Vulgate (Genesis 5; Genesis 11) or the Hebrew Tanakh (Gen 5; Gen 11). The net difference between the two majorgenealogies of Genesis is 1466 years (ignoring the "second year after the flood" ambiguity), 85% of the total difference. (See Dating creation.)

Jewish tradition[edit]

During the Talmudic era, from the 1st to the 10th centuries AD, the center of Jewish world was in the Middle East, primarily in the Talmudic Academies of Iraq and Palestine. Jews in these regions used Seleucid Era dating (also known as the "Anno Graecorum (AG)" or the "Era of Contracts") as the primary method for calculating the calendar year.[8] For example, the writings of Josephus and the Books of the Maccabees used Seleucid Era dating exclusively, and the Talmud tractate Avodah Zarah states:
Rav Aha b. Jacob then put this question: How do we know that our Era [of Documents] is connected with the Kingdom of Greece at all? Why not say that it is reckoned from the Exodus from Egypt, omitting the first thousand years and giving the years of the next thousand? In that case, the document is really post-dated!
Said Rav Nahman: In the Diaspora the Greek Era alone is used. He [the questioner] thought that Rav Nahman wanted to dispose of him anyhow, but when he went and studied it thoroughly he found that it is indeed taught [in a Baraita]: In the Diaspora the Greek Era alone is used.[9]
Occasionally in Talmudic writings, reference was made to other starting points for eras, such as Destruction Era dating,[10] being the number of years since the 70 ADdestruction of the Second Temple, and the number of years since the Creation year based on the calculation in the Seder Olam Rabbah of Rabbi Jose ben Halafta in about 160 AD.[11] By his calculation, based on the Masoretic Text, Adam and Eve were created on 1st of Tishrei (Rosh Hashanah Day 1) in 3761 BC,[12][13][14] later confirmed by the Muslim chronologist al-Biruni as 3448 years before the Seleucid era.[15] An example is the c. 8th-century AD Baraita of Samuel.
In the 8th and 9th centuries AD, the center of Jewish life moved from Babylonia to Europe, so calculations from the Seleucid era "became meaningless".[8] From the 11th century, anno mundi dating became dominant throughout most of the world's Jewish communities, replacing the Seleucid dating system.[8][16] The new system reached its definitive form in 1178 AD when Maimonides completed the Mishneh Torah. In the section Sanctification of the Moon (11.16), he wrote of his choice of Epoch, from which calculations of all dates should be made, as "the third day of Nisan in this present year ... which is the year 4938 of the creation of the world" (March 22, 1178 AD).[17] He included all the rules for the calculated calendar epoch and their scriptural basis, including the modern epochal year in his work, and establishing the final formal usage of the anno mundi era.
Today, the rules detailed in Maimonides' calendrical code are those generally used by Jewish communities throughout the world. The first day of creation is established as the 25th of Elul AM 0, on which God created existence, time, matter, darkness and light out of void.[13][14] On the sixth day of creation (which corresponds to Rosh Hashanah day 1), God created Adam and Eve, identified in the Hebrew calendar as the 1st of Tishrei.[12] It is this date that fixes the Hebrew calendar's AM epoch: 1 Tishrei AM 1, also known as Sunday/Monday, 6/7 October 3761 BC (Julian) or Sunday/Monday, 6/7 September -3760 (Gregorian).[18][19] Though Rosh Hashanah may not fall on a Sunday, 1 Tishrei AM 1 is Monday, like the later day of its Julian or Gregorian conversion. Monday simply begins at sunset in the Hebrew calendar, earlier than on the Julian or Gregorian.

Greek tradition[edit]

The inscription over the Bevis Marks Synagogue, City of London, gives a year in Anno Mundi (5461) and Anno Domini (1701).
The Septuagint was the most scholarly non-Hebrew version of the Old Testament available to early Christians. Many converts already spoke Greek, and it was readily adopted as the preferred vernacular-language rendering for the eastern Roman Empire. The later Latin translation called the Vulgate, an interpretative translation from the later Masoretic Text (a Jewish revision and consolidation of earlier Hebrew texts), replaced it in the west after its completion by St. Jerome c. 405, Latin being the most common vernacular language in those regions.

Earliest Christian chronology[edit]

The earliest extant Christian writings on the age of the world according to the biblical chronology were therefore based on the Septuagint, due to its early availability. They can be found in the Apology to Autolycus (Apologia ad Autolycum) by Theophilus (AD 115-181), the sixth bishop of Antioch,[20] and the Five Books of Chronology by Julius Africanus (AD 200-245).[21]

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