The Constellations How today's 88 constellations came to be Part 3: Today's 88 Constellations

In 1610, Galileo Galilei pointed a telescope at the stars and in one instant, the universe became a lot bigger. With better telescopes, our understanding of the universe grew exponentially to a point where we have now looked back twelve billion light years. With more and more stars discovered, the number of constellations grew - at one point (in 1801) to over one hundred. At the end of the 19th century, astronomers started to work out a standard, which resulted in 88 acknowledged constellations in 1928.

Bits of the history of our constellations, Part 3

Filling in the Gaps in the Northern Sky (1687) In 1641, Polish astronomer Johannes Hevelius built an observatory on the roofs of his three connected houses. Here, Hevelius and his second wife Elisabeth compiled data of no less than 1,564 stars - the largest number ever observed with the naked eye - in a star catalogue called Catalogus Stellarum Fixarum. Johannes Hevelius died in 1687. The catalogue, together with an introduction and a star atlas called Firmamentum Sobiescianum were published by Elisabeth Hevelius in 1690. The catalogue and the atlas contained ten new constellations, seven of which are still used today. The constellation Sextant was named after the instrument Hevelius and his wife used for the observations. Hevelius' observations were the last star catalogue that was compiled with the naked eye. Sources: Wikipedia, Ian Ridpath

Hevelius and his wife observing the sky with a brass sextant Source: Wikipedia

Hevelius' Constellations

Canes Venatici Hunting Dogs	Cerberus Cerberus	Lacerta Lizard	Leo Minor Little Lion	Lynx Lynx
Mons Maenalus Mount Maenalus	Scutum Shield	Sextans Sextant	Triangulum Minus Little Triangle	Vulpecula et Anser Fox

Flamsteed's Catalogue (1725) In 1675, English astronomer John Flamsteed was appointed the first Astronomer Royal. In this position, he assembled the first major star catalogue that was made with the aid of a telescope. It contained over 3,000 stars, doubling the number of stars observed by Hevelius. The Catalogue, called Catalogus Britannicus was published posthumously in 1725. One of the "stars" in Flamsteed's Catalogue was the planet Uranus. However, it was not identified as planet until 1781, when William Herschel observed it. While Flamsteed didn't receive credit for the planet he discovered, his name was immortalized for something he didn't invent: the Flamsteed Numbers, which identify individual stars in a constellation. Sources: Wikipedia, Ian Ridpath

John Flamsteed Source: Wikipedia

Filling in the Gaps in the Southern Sky (1750-1763) In 1750, French astronomer Nicolas-Louis de Lacaille set up a small observatory at the southern tip of Africa, the Cape of Good Hope. Here, within four years, he observed 9,766 stars. Lacaille returned to France in 1754. His catalogue, called Coelum Australe Stelliferum was published in 1763. It contained fourteen new constellations. One of them was named after the Table Mount where de Lacaille conducted his observations. The other thirteen symbolized the Age of Enlightenment. They were named after scientific instruments and artist's tools, including some unfamiliar ones like Fornax Chemica (the Chemical Oven) or Antlia Pneumatica (the Pneumatic Pump). In the same publication, de Lacaille also divided the oversized constellation Argo Navis into three separate entities - a move that was made official by the IAU in 1928 (see below). Sources: Wikipedia, Ian Ridpath, archive.org

Nicolas-Louis de Lacaille Source: Wikipedia

de Lacaille's Constellations

Antlia Air Pump	Caelum Chisel	Circinus Draftsman's Compass	Fornax Furnace	Horologium Pendulum Clock	Mensa Table Mount	Microscopium Microscope
Norma Set Square	Octans Octant	Pictor Easel	Pyxis Mariner's Compass	Reticulum Cross-hairs Net	Sculptor Sculptor	Telescopium Telescope

Connecting the Dots - Nouvelle Uranographie (1786) Today, the most common depiction of a constellation is a diagram of the brightest stars, connected by thin lines. One could easily assume that this has been the common wayto depict constellations for a long time, but up until the the late 18th century, all constellations were described by rather elaborate pictures. The geometrical rendering of the constellations was invented by an almost forgotten French astronomer. Ian Ridpath writes in "Pictures of Matchstick Men":

Ruelle's renderings of Ursa Major and Ursa Minor Source: Teca Digitale Viewer

"Alexandre Ruelle (1756–18??) [was] an assistant at Paris Observatory in pre-revolutionary France. Extending the growing revolutionary fervour to the sky, Ruelle swept away the conventional constellation shapes of the astronomical ancien régime and substituted a sparer, more proletarian style. He presented his results in 1786 on a chart titled Nouvelle uranographie, consisting of northern and southern hemispheres with an equatorial strip below. In the accompanying booklet he explained his rationale: I thought there could be no simpler and easier way of teaching the knowledge of the sky than to substitute for these fantastic figures triangles, squares, polygons or other geometric figures which really make visible the various groups of stars by supposing the brightest stars of each constellation linked together by lines." Ruelle's concept took on only slowly. Two of the most popular presentatations of constellations as pictures (Bode's Uranographia and Urania's Mirror) were published 15 and 38 years respectively, after Ruelle's publication. Today, however, the "Matchstick Men" are the most common way to depict constellations.

Ruelle's renderings of Orion Source: Teca Digitale Viewer

There is no official rule of how to draw the lines between the stars of a constellation, leaving some room for creative interpretations. Sources: Ian Ridpath: Pictures of Matchstick Men, Anthony Auerbach: Joining the Dots

100 Constellations and more - Bode's Uranographia (1801) In 1801, Johann Elert Bode, director of the Berlin Observatory published a star catalogue listing 17,240 stars. Uranographia was not only the to-date largest star catalogue, it also marked the climax of an epoch of artistic representation of the constellations. As there was still no governing body, many astronomers tried to get their names (or their ideas) written in the sky and so, Bode's catalogue contained over 100 constellations, among them innovative ideas like Bode's creation Officina Typographica, commemorate Johannes Gutenberg’s printing press, but also an entire zoo with slugs, leeches, sea horses and even a flying squirrel. Sources: Wikipedia, Ian Ridpath

Uranographia title page Source: Linda Hall Library

Drawing Lines between Constellations (1874) While working on his Uranometria Argentina, US-American astronomer Benjamin Gould tackled a problem that arose with the invention of the telescope: Since the times of Ptolemy, there had been a consensus about which bright stars belonged to which constellation. However, the patterns of the traditional constellations were based on the 6,000 stars visible to the naked eye. The number of known stars grew with every new stronger telescope - in the mid-19th century it had risen to 325,000 - and most of them were orphaned between the traditional constellations.

Gould's Border between Lupus and Centaurus Source: Paolantonio, Garcia

Gould was the first one to draw border lines between constellations using arcs of right ascension circles and parallels of declination. With that approach, every star could be assigned to one of the traditional constellations. In 1928, when the International Astronomical Union standardized the star maps, Gould's boundaries of the southern constellations was addopted almost without change and his concept was extended to the constellations of the northern hemisphere. Source: Paolantonio, Garcia: Uranometria Argentina and the constellation boundaries

A Book about Star Lore (1899) Richard Hinckley Allen, born in 1838, Buffalo, New York wanted to become an astronomer, but his poor eyesight crashed his dream. Instead of discovering new stars, he collected stories about the existing ones. His book Star Names: Their Lore and Meaning , published in 1899 was the first comprehensive collection of astronomical information about stars and constellations, paired with the myth and legend behind them. He collected Greco-Roman stories as well as Arabic, Babylonian, Indian and Chinese myth. His book met criticism regarding its reliability, but it still remains the first large collection of star lore in printed form. Source: Wikipedia

Star Names & their Meanings Source: archive.org

Setting final Boundaries (1922-1928) At the end of the 19th century, the international astronomic community had worked out an understanding on which constellations should remain and which should be scraped. Above mentioned R.H. Allen wrote, From 80 to 90 constellations may be considered as now more or less acknowledged. In 1922, the International Astronomical Union was founded. At its first General Assembly, the IAU officially adopted a list of 86 constellations covering the entire sky. One final adjustment to the selection of constellations was made in 1928, when the IAU adopted de Lacaille's suggestion to divide Ptolemy's large constellation Argo Navis (The Ship) into three smaller constellations. Sources: Wikipedia, Ian Ridpath The Breaking up of Argo Navis Carina Keel Puppis Poop Deck Vela Sails

Constellations with modern boundaries Source: universalworkshop.com

Wikipedia and Ian Ridpath provide detailed tables of the 88 IAU designated constellations and their history. One last issue needed to be solved: Traditional star maps displayed constellations with selected stars that were either defined by pictures or connected by lines. That system left a lot of orphaned stars between the constellations and with ever improving telescopes, the number of orphans kept rising. To fix the border dispute, Belgian astronomer Eugène Delporte was contracted to draw border lines between the constellations along lines of right ascension and declination, so that every point in the sky would belong to one constellation. Delporte's work was officially adopted in 1928 and published in 1930, resulting in the 88 modern constellations we still use today. Sources: Wikipedia, Ian Ridpath

Eugène Joseph Delporte Source: bestor.be

The darkest Part of the Sky - Hubble Deep Field (1995) In the years since the founding of the IAU, telescopes have improved tremendously. Arguably the most famous one is NASA's Hubble Space Telescope, which has been in Earth orbit since 1990. Between December 18 and 28, 1995, Hubble's Wide Field and Planetary Camera 2 was pointed at a small region in the constellation Ursa Major - totally dark to the naked eye. After 342 separate exposures, a picture emerged, showing about 3,000 objects - almost all of them galaxies, some of which are among the youngest and most distant known. 3,000 Galaxies, each of them consisting of an average of 100 Million stars, revealed in a "dark" spot that represents one 24-millionth of the whole sky! Source: Wikipedia

Hubble Deep Field; Source: Wikipedia

A Billion Stars and counting (2018) In times of refraction telescopes and pen and paper, the size of star catalogues was not only limited by the telescope's resolution but also - or even more so - by the limited time and the limited amount of numbers a human can scribble in any considerable amount of time. Modern computers have taken care of the problem. In 2013, the European Space Agency launched the Gaia space observatory, aiming to construct by far the largest and most precise 3D space catalog ever made. Sources: Wikipedia, ESA

Artist's impression of the Gaia Telescope; ESA

After two data releases in 2015 and 2018, the Gaia Star Catalogue currently contains no less than 1,692,919,135 objects, mainly stars, but also planets, comets, asteroids and quasars and others. The bad news: No human will ever be able to appreciate the entire catalogue. Just reading the coordinates of 1.7 billion stars at human speed would take about 150 years. The good news: All those billions of stars fit neatly into a system of 88 constellations that was designed before the age of computers!

The Largest Map of the Universe (2020) On July 20, 2020, the team of the Sloan Digital Sky Survey (see above) released the largest-ever 3-D-map of the universe. In five years of data collection, over 100 astrophysicists contributed to the map. Most important part of the project was eBOSS, the Extended Baryon Oscillation Spectroscopic Survey, a survey of quasars and galaxies as part of the Sloan Survey. The map shows 11 billion years of the universe's history. Sources: scitechdaily.com, space.com

3-D-map of the Universe; Source: anews.com

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