The Prime Meridian is both a thing and a concept. The word Prime has a vast number of usages as a noun, verb and adjective - for example there are prime numbers, prime rib, prime cuts of meat, one can prime a surface for painting, prime a well and prime certain antique weapons and there is the concept of a Prime Meridian. Da Wiki tells us that:

In geography and geodesy, a meridian is the locus connecting points of equal longitude, which is the angle (in degrees or other units) east or west of a given prime meridian (currently, the IERS Reference Meridian). In other words, it is a coordinate line for longitudes, a line of longitude.

, which gets us a bit ahead of out story and is very much earth centric. The "celestial sphere", the moon, all of the planets and all of their moons also have meridians as well as their own "Prime meridians". Generally, then, a meridian is an ellipse (including a circle) that runs through both poles of a planet or moon. A prime meridian is an arbitrary meeridian selected and designated as such in order that it may be used as a reference arc for specifying locations and navigating.

The wiki on "meridian" cited above tells us that Eratosthenes invented the first Prime Meridian back in 200 BCE. He did many things, and may have invented the concept for his local culture but that is pretty late in the day for anybody to be the first to use such a concept and the wiki for Prime meridian contradicts this assertion. It notes a fourth century CE Indian astronomical treatise which described the thousands of years old customs of the prime meridian, or zero longitude, as passing through a couple of specific locations. It seems reasonable to assume that many or most peoples who engaged in significant amounts of journeying developed somewhat similar systems for identifying where they were and where they were going. We know that many such meridians were specified by various countries and others over the ages including the monstrously evil Tordesillas line blessed by Pope Julius II who signed off on it on January 24, 1506.

Since the whole point is all about navigation, sea faring nations and England in particular took a great interest in the matter. In the later 1700s and early 1800s, the UK Royal Astronomer, one Nevil Maskelyne began cranking out issues of The Nautical Almanac and Astronomical Ephemeris for use in navigating. These, naturally, took the meridian of The Royal Observatory, Greenwich as the base or prime meridian. These, and hence that meridian, became the standard, even in France. As a result, a conference in 1884 made it official that the Greenwich (pronounced grenitch) meridian would be used as the prime meridian. However, stuff like that cannot long stand. Just as Greenwich Mean Time (GMT) became Coordinated Universal Time (UTC - don't ask me why), the zero merician could not stay Greenwich. It was replaced with the IERS Reference Meridian further abbreviated the IRM 100 years after being adopted. This new standard is not just a rename, but was newly determined using lasers and satellites, oh my (W00t!) and is now 102 meters east of where it was. I mean, that is just sooo cool, and, while it is nice to have blisteringly precise tech, the damn imaginary line is, as noted above, fookin' arbitrary, but, whatever. Next time they move it I suggest that they run it through the bandstand in the Plaza Republica in Mazatlan, or maybe somewhere in Vera Cruz

On this day in history:

1493 – Christopher Columbus first sighted the island of Dominica

1534 – The English Parliament passed the first Act of Supremacy, making King Henry VIII head of the Anglican Church
(died 65)

1783 – The American Continental Army was disbanded. Please don't tell Donald J Trump.

1793 – French playwright, journalist and feminist Olympe de Gouges was guillotined.

1817 – The Bank of Montreal, Canada's oldest chartered bank, opened

1838 – The Times of India, was founded as The Bombay Times and Journal of Commerce.

1848 – A greatly revised Dutch constitution, which transferred much authority from the king to his parliament and ministers, was proclaimed.

1868 – John Willis Menard (R-LA) was the first African American elected to the United States Congress. Because of an electoral challenge, he was never seated. Odd how that worked

1903 – Encouraged bythe United States, Panama separated from Colombia, but not the US.

1920 – The Russian Army retreated to Crimea, after a successful offensive by the Red Army

1929 – The Gwangju Student Independence Movement occurred.

1946 – The Constitution of Japan was adopted through Emperor's assent.

1956 – The Khan Yunis killings by the Israel Defense Forces in Egyptian-controlled Gaza resulted in the deaths of 275 Palestinians.

1957 –The USSR launched Sputnik 2 carrying the dog Laika, the first animal to enter orbit

1961 – U Thant was unanimously appointed to be the 3rd Secretary-General of the United Nations

1973 – NASA launched Mariner 10 toward Mercury.

1979 – Five members of the Communist Workers Party were shot dead and seven were wounded by a group of Klansmen and neo-Nazis

1986 – The Lebanese magazine Ash-Shiraa reported that the US had been secretly selling weapons to Iran

1986 – The Compact of Free Association became law granting the Federated States of Micronesia and the Marshall Islands independence from the United States.

2014 – One World Trade Center officially opened in New York City,

Some people who were born on this day:

He who sees the truth, let him proclaim it, without asking who is for it or who is against it.

~~ Henry George

AD 39 – Lucan, poet
1500 – Benvenuto Cellini, sculptor and painter
1505 – Achilles Gasser, physician and astrologer
1560 – Annibale Carracci, painter and illustrator
1587 – Samuel Scheidt, organist, composer, and educator
1656 – Georg Reutter, organist and composer
1689 – Jan Josef Ignác Brentner, composer
1749 – Daniel Rutherford, chemist and physician
1793 – Stephen F. Austin, businessman and politician
1794 – William Cullen Bryant, poet and journalist
1801 – Vincenzo Bellini, composer
1815 – John Mitchel, journalist and activist
1854 – Carlo Fornasini, micropalaeontologist
1862 – Henry George, journalist and politician
1877 – Rosalie Edge, environmentalist
1878 – Bangalore Nagarathnamma, Carnatic singer and activist
1901 – André Malraux, historian, theorist, and author
1909 – James Reston, journalist and author
1917 – Annapurna Maharana, activist
1918 – Elizabeth P. Hoisington, general
1918 – Russell B. Long, lieutenant, lawyer, and politician, helped LBJ with War on Poverty

1930 – Mable John, blues singer
1930 – Tsutomu Seki, astronomer and academic
1933 – John Barry, composer and conductor
1933 – Ken Berry, actor, singer, and dancer
1940 – Sonny Rhodes, singer, songwriter, and guitarist
1943 – Bert Jansch, singer, songwriter, and guitarist
1945 – Nick Simper, bass guitarist
1948 – Lulu, singer, songwriter, and actress
1951 – Ed Murawinski, cartoonist
1953 – Helios Creed, singer, songwriter, and guitarist
1954 – Adam Ant, singer, songwriter, and actor
1955 – Teresa De Sio, singer, songwriter, and guitarist
1956 – Chrystian, sertanejo singer
1960 – Ian McNabb, singer, songwriter, and musician
1967 – Mark Roberts, singer and guitarist
1967 – Steven Wilson, singer, songwriter, guitarist, and producer
1973 – Mick Thomson, guitarist
1976 – Jake Shimabukuro, ukulele player and composer
1978 – Tim McIlrath, singer, songwriter, and guitarist
1978 – Jonas Howden Sjøvaag, drummer
1983 – Myrna Braza, singer and songwriter
1987 – Courtney Barnett, singerm songwriter, and guitarist
1989 – Paula DeAnda, singer, songwriter, and actress
1989 – Joyce Jonathan, singer, songwriter, and guitarist

Some people who died on this day:

I don't ever want to grow up. That's boring.

~~ Quincy Jones

1643 – John Bainbridge, astronomer and academic
1643 – Paul Guldin, astronomer and mathematician
1890 – Ulrich Ochsenbein, lawyer and politician, 1st President of the Swiss National Council
1933 – Pierre Paul Émile Roux, physician, bacteriologist, and immunologist
1939 – Charles Tournemire, organist and composer
1954 – Henri Matisse, painter and sculptor
1956 – Jean Metzinger, artist,
1980 – Caroline Mytinger, painter and author
1991 – Chris Bender, singer
1993 – Léon Theremin, physicist and engineer, invented the Theremin
1997 – Ronald Barnes, carillon player and composer
1998 – Bob Kane, author and illustrator, co-created Batman
2002 – Lonnie Donegan, singer, songwriter, and guitarist
2006 – Paul Mauriat, pianist, composer, and conductor
2012 – Carmélia Alves, singer
2016 – Kay Starr, singer
2024 – Quincy Jones, producer

Some Holidays, Holy Days, Festivals, Feast Days, Days of Recognition, and such:

National Bison Day
National Cinnamon Day
National Wine Tasting Day
Prime Meridian Day

Today's Tunes

Samuel Scheidt

Georg Reutter

Jan Josef Ignác Brentner

Vincenzo Bellini

Mable John

Sonny Rhodes

Bert Jansch

Nick Simper

Lulu

Teresa De Sio

Chrystian

Ian McNabb

Jake Shimabukuro

Jonas Howden Sjøvaag

Myrna Braza

Joyce Jonathan

Leon Theremin

Lonnie Donegan

Kay Starr

Quincy Jones

Ok, it's an open thread, so it's up to you folks now. What's on your mind?

Cross posted from http://caucus99percent.com

Open Thread, Prime Meridian, Laika, Mabel john, Lulu, Leon Theremin, Lonnie Donegan, Quincy Jones