Parsec definition , created by Parsec Enterprises, Sam Younghans
Cosmic Parsec
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"It's the ship that made the Kessel Run in less than 12 parsecs."  Han Solo, to Ben Kenobi and Luke Skywalker, about the ship, Millennium Falcon. In the Cantina scene of Star Wars.
Parsec {pahr'-sek} (pc), a unit used in astronomy, is the distance at which a star's PARALLAX (apparent shift as measured from opposite points on a base line equivalent to the radius of the Earth's orbit) is 1 second of arc. The parsec equals 3.26 light-years; 206,265 astronomical units; 3.086 X (10 to the power of 13) kilometers; or 1.917 X (10 to the power of 13) miles. If parallax is given in seconds, the reciprocal is distance in parsecs. Astronomical unit, (AU), mean distance between the earth and the sun. One AU is c.92,960,000 mi (149,604,970 km).

Established in 1976. Parsec Enterprises owned the Counterpoint Theater and produced  plays (along with Children's Christmas plays), concerts and community fund raisers in California. It has been active coordinating entertainment for The Muscular Dystrophy Telethons (3 Years). Was involved with the promotion and the entertainment for The Buck Owens Rodeo Days (3 Years). Produced "The Saga of Sonoma" for the City of Sonoma. Worked on promotional projects with the Film Advisory Board in Hollywood.
Conceived and coordinated a 90 minute Merv Griffen Show, paying tribute to Tay Garnett, a Hollywood film producer/director. The guests for the show were: Walter Pidgeon, Eve Arden, Lloyd Nolan and George Murphy.

Sam Younghans, President of Parsec Enterprises:  produced radio and television commercials. Handled the Artist relations and productions at the Beverly Hilton Hotel for Marathon Productions. Those shows included: Johnny Mathis, Josephine Baker, Bill Cosby, Ed McMahon and Ike and Tina Turner.  Did the artist relations for Marquee Enterprises, who booked all of the top Las Vegas Acts (too many to list here). See some of the list.
        Sam has worked as a computer consultant for over 10 years in Hollywood and San Diego. Was LAN supervisor and Computer MIS for a manufacturing company in San Diego for six years.
Click here for more history about Sam. 

Sent: Sunday, February 18, 2001 12:06 PM
Subject: A symbol
I have been using this logo since 1976. At that time I read a very interesting story about one of the first colonies on the Eastern shores of Mexico, probably on the Yucatan Peninsula. The story told of a great king that settled a colony and how the colony grew and prospered until they were invaded from the sea. There was a drawing that may have been the kings head dress. I copied it and incorporated it into my logo.  
I have moved many times since then and lost track of the book. I was wondering if it has any meaning to you or do you recognize it from the many drawings you have encountered. I caught part of the PBS NOVA show last night and was fascinated. I tuned in just as they were showing your history. Amazing! Would appreciate any feed back.
Sam Younghans

Dear Mr. Younghans,

Thanks for your message regarding your logo.  I do indeed recognize it, though I can't claim to know the book wherein you saw it originally.  The symbol is an Aztec hieroglyph that records a day in their 260-day calendar (one of several Mesoamerican day counts we know of). It is simply "One Reed," or Ce Acatl in Nahuatl. The small circle at bottom is the numeral one and the upper plant-like element is just that -- the sign for "Reed."  Individual days were designated by one of twenty day names combined by a number prefix from 1-13 (13 x 20), so "One Reed" is a station in this ongoing count.  The mythological associations you mention probably concern a figure named Topiltzin Quetzalcoatl, a culture hero of Central Mexican history who ruled a place called Tollan, or Tula.  His birth date was said to be One Reed, and following customs of the period this came to be incorporated into his name, fully given sometimes as Ce Acatl Topiltzin Quetzalcoatl.  
I hope this helps to explain it.
David Stuart
Department of Anthropology,
Peabody Museum, Harvard University



The two highest-ranking priests of the Aztecs ministered, respectively, to the war god and the god of rain. Both bore the title Quetzalcoatl, or "feathered serpent", to elevate their status by association with the god Quetzalcoatl and the Toltec god-king of that name. One was called "Quetzalcoatl priest of our lord " and the other " Quetzalcoatl priest of Tlaloc ". But the human blood in which their hands were drenched is strangely at variance with the honorific which they shared. For Quetzalcoatl, at least in his incarnation as the god-king of Tula, called for an end to human sacrifice.

Chicxulub, Yucatan Peninsula, Mexico
 21░20'N, 89░30'W; diameter: 170 km; age: 64.98 million years

This three-dimensional map of local gravity and magnetic field variations shows a multi-ringed structure called Chicxulub named after a village located near its center. The impact basin is buried by several hundred meters of sediment, hiding it from view. This image shows the basin viewed obliquely from approximately 60░ above the surface looking north, with artificial lighting from the south. The image covers 88 to 90.5░ west longitude and 19.5 to 22.5░ north latitude. NASA scientists believe that an asteroid 10 to 20 kilometers (6 to 12 miles) in diameter produced this impact basin. The asteroid hit a geologically unique, sulfur-rich region of the Yucatan Peninsula and kicked up billions of tons of sulfur and other materials into the atmosphere. Darkness prevailed for about half a year after the collision. This caused global temperatures to plunge near freezing. Half of the species on Earth became extinct including the dinosaurs. (Image courtesy of V. L. Sharpton, LPI)

Who invented the word Parsec? I found this on the web, so I linked to it. It may not be there too long. If you go to it and it is no longer there, please let me know.


Who invented the term "parsec"?

In a discussion originally posted on sci.astro, Apr 2002
Poor Richard asked:
Does anyone here know the origin of this unit of measurement ? I know the definition of it, I am just curious who the first person to use it was ...

Answer: The first appearance of the word "parsec" in the title or abstract of any paper in the ADS occurs in 1922, in a work by Hertzsprung.  The paper itself isn't available via ADS, unfortunately - a quick scan of papers in the 1870s and 1880s via ADS shows that most astronomers contented themselves with quoting parallaxes in arc-seconds.  A few used "light year" or an equivalent phrase to express distance.  I didn't see "parsec" in the few papers I read.
- the book "Star Names: Their Lore and Meaning," by Richard Allen, was published in 1899; at least, my copy is a facsimile of an 1899 edition.  Allen uses "light years" to express the distance to Sirius and alpha Centauri, and the word "parsec" doesn't appear in the index.
      My guess is that the term was invented sometime after 1900.  You might look in books by Agnes Clerk or Simon Newcomb.  The book "Parallax" by Alan Hirshfield, published just last year, might be a good place to look.

I did a little extra digging, and found this site describing Herbert Hall Turner, who won the Bruce Medal in 1927:

The site says, "Turner is generally credited with coining the term parsec." Searching ADS for papers by Turner, I see that he uses "light years" to describe the distance to Nova Persei 1901, in a paper published in Nov, 1918. He uses "parsecs" in a paper on stars in Monoceros,
published in Jan, 1921, but does not define it.

  I leave further work to someone with a good library of old astronomical journals.  Sigh.  Life was good when I was working at Princeton -- the Dept. of Astrophysical Sciences had their own library, with volumes of all the major journals going back to volume 1, and nearly complete sets of even minor publications like "The Observatory."  Those were the good old days ... :-/


   Martin Hardcastle found a good reference: The OED says as its first quotation: 1913 F. W. DYSON in Monthly Notices R. Astron. Soc. LXXIII. 342  There is need for a name for this unit of distance... Professor
   Turner suggests Parsec, which may be taken as an abbreviated form of a distance corresponding to a parallax of one second'.

I followed the reference using the ADS and posted a little more information: Thanks, Martin!  I have found the article itself via the ADS --
it appears in an article titled "Stars, Distribution and drift of,
The distribution in space of the stars in Carrington's
Circumpolar Catalogue".  The attribution appears in a footnote
as Dyson discusses the distance to a star:  the main text reads

     ... Taking the unit of distance R* to be that corresponding
      to a parallax of 1.0 arcsec ...
and the footnote
      * There is a need for a name for this unit of distance.
        Mr. Charlier has suggested Siriometer, but if the violence
        to the Greek language can be overlooked, the word ASTRON
        might be adopted.  Professor Turner suggests PARSEC,
        which may be taken as an abbreviated form of "a distance
        corresponding to a parallax of one second."

  Can anyone trace the word further back than this?

You can see the full article at this
              link from the ADS .
  (pÔr┤symbollăks) , any alteration in the relative apparent positions of objects produced by a shift in the position of the observer. In astronomy the term is used for several techniques for determining distance. Trigonometric parallax is the apparent displacement of a nearby star against the background of more distant stars resulting from the motion of the earth in its orbit around the sun. Formally, the parallax of a star is the angle at the star that is subtended by the mean distance between the earth and the sun. A shift in the angular position of a star will be greatest when observed at intervals of six months; this makes the parallax equal to the value of one half of the semiannual displacement of the star. If a star's parallax can be measured, it then determines the distance to the star. A unit of stellar measurement is the parsec; it is the distance at which a star would have a parallax of one second of arc and is equivalent to 206,265 times the distance from the earth to the sun, or about 3.3 light-years. A star's distance d in parsecs is the reciprocal of its parallax p (or d = 1/p). The first stellar parallax was measured in 1838 by Friedrich Bessel for the star 61 Cygni. Its parallax of 0.3 places it at a distance of 3.3 parsecs or about 11 light-years. The technique of stellar parallax is useful for stars within 100 parsecs. Spectroscopic parallax is the most widely used technique for determining the distances of stars that are too distant for their stellar parallaxes to be measured. From the analysis of a star's spectrum, its position on the Hertzsprung-Russell diagram is determined. This diagram correlates the spectral class of the star with its absolute magnitude. By comparing the absolute magnitude to its apparent brightness, the star's distance is calculated. Dynamical parallax is a method for determining the distance to a visual binary star. The angular diameter of the orbit of the stars around each other and their apparent brightness are observed. By applying Kepler's laws and the mass-luminosity relation, the distance of the binary star can be determined. Geocentric parallax is a technique similar to stellar parallax, which uses the diameter of the earth rather than the diameter of its orbit as a baseline. Because this baseline is relatively small, the technique is useful only for close celestial objects such as the moon or the asteroids.  
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