Constellations | Can’t Sleep? Learn About The Night Sky

For thousands of years, people have looked to the night sky and imagined familiar shapes among the stars. This episode explores the stories connected to constellations, how they help map the heavens, and how they are used in modern astronomy. Along the way, you’ll hear about zodiac constellations, celestial navigation, and the 88 official constellations recognized today.

It’s steady and consistent, with no whispering and no sudden changes, just enough to give your mind something to follow as you wind down. Happy sleeping!

Transcript

Welcome to the I Can't Sleep Podcast, Where I help you drift off one fact at a time. I'm your host, Benj Momboster, And today's episode is about constellations. A constellation is an area on the celestial sphere in which a group of visible stars forms a perceived pattern or outline, Typically representing an animal, Mythological subject, Or inanimate object. The first constellations were likely defined in prehistory. People use them to relate stories of their beliefs, Experiences, Creation, And mythology. Different cultures and countries invented their own constellations, Some of which lasted into the early 20th century before today's constellations were internationally recognized. The recognition of constellations has changed significantly over time. Many changed in size or shape. Some became popular, Only to drop into obscurity. Some were limited to a single culture or nation. Naming constellations also helped astronomers and navigators identify stars more easily. Twelve or thirteen ancient constellations belong to the zodiac, Straddling the ecliptic which the sun, Moon, And planets all traverse. The origins of the Zodiac remain historically uncertain. Its astrological divisions became prominent circa 400 BC in Babylon or Chaldean astronomy. Constellations appear in Western culture via Greece and are mentioned in the works of Hesiod, Eudoxus, And Aratus. The traditional 48 constellations consisting of the Zodiac and 36 more, Now 38, Following the division of Argo Navis into three constellations, Are listed by Ptolemy, A Greco-Roman astronomer from Alexandria, Egypt, In his homagist. The formation of constellations was the subject of extensive mythology, Most notably in the metamorphoses of the Latin poet Ovid. Constellations in the far southern sky were added from the 15th century until the mid-18th century, When European explorers began traveling to the southern hemispheres. In 1922, The International Astronomical Union, IAU, Formally accepted the modern list of 88 constellations. And in 1928 adopted official constellation boundaries that together cover the entire celestial sphere. Any given point in a celestial coordinate system lies in one of the modern constellations. Some astronomical naming systems include the constellation where a given celestial object is found to convey its approximate location in the sky. The Flamsteed designation of a star, For example, Consists of a number and the genitive form of the constellation's name. Other star patterns or groups, Called asterisms, Are not constellations under the formal definition, But are also used by observers to navigate the night sky. Asterisms may be several stars within a constellation, Or they may share stars with more than one constellation. Examples of asterisms include the teapot within the constellation Sagittarius, Or the Big Dipper in the constellation of Ursa Major. The word constellation comes from the late Latin term constellatio, Which can be translated as set of stars. It came into use in Middle English during the 14th century. The ancient Greek word for constellation is astron. These terms historically referred to any recognizable pattern of stars whose appearance was associated with mythological characters or creatures, Earth-bound animals, Or objects. Over time, Among European astronomers, The constellations became clearly defined and widely recognized. In the 20th century, The International Astronomical Union recognized 88 constellations, Each of which has a Latin name. A constellation or star that never sets below the horizon when viewed from a particular latitude on Earth is termed circumpolar. From the North Pole or South Pole, All constellations south or north of the celestial equator are circumpolar. Depending on the definition, Equatorial constellations may include those that lie between declinations 45°N and 45°S. Or those that pass through the declination range of the ecliptic or zodiac, Ranging between 23. 5°N and 23. 5°S. Stars and constellations can appear near each other in the sky, But they usually lie at a variety of distances away from the Earth. Since each star has its own independent motion, All constellations will change slowly over time. After tens to hundreds of thousands of years, Familiar outlines will become unrecognizable. Astronomers can predict the past or future constellation outlines by measuring common proper motions of individual stars by accurate astrometry and their radial velocities by astronomical spectroscopy. The 88 constellations recognized by the IAU, As well as those by cultures throughout history, Are imagined figures and shapes derived from patterns of stars in the observable sky. Many officially recognized constellations are based on the imaginations of ancient Near Eastern and Mediterranean mythologies. Some of these stories seem to relate to the appearance of the constellations, E. G. The assassination of Orion by Scorpius, Their constellations appearing at opposite times of year. Constellation positions change throughout the year due to night on Earth occurring at gradually different portions of its orbit around the Sun. As Earth rotates toward the east, The celestial sphere appears to rotate west, With stars circling counterclockwise around the northern pole star and clockwise around the southern pole star. Because of Earth's 23. 5 degree axial tilt, The zodiac is distributed equally across hemispheres along the ecliptic, Approximating a great circle. Zodiacal constellations of the northern sky are Pisces, Aries, Taurus, Gemini, Cancer, And Leo. In the southern sky are Virgo, Libra, Scorpius, Sagittarius, Capricornus, And Aquarius. The ecliptic appears overhead from latitudes of 23. 5°N to 23. 5°S. In both hemispheres, Zodiac appears low during summer and high during winter. While due to the Earth's tilt, It descends nightly during spring and ascends in autumn. Due to the solar system's 60-degree tilt, The galactic plane of the Milky Way is inclined 60 degrees from the ecliptic, Between Taurus and Gemini, North, And Scorpius and Sagittarius, South and near the galactic center, Can be found. The galaxy appears to pass through Aquila, Near the celestial equator, And northern constellations Cygnus, Cassiopeia, Perseus, Auriga, And Orion, Near Betelgeuse, As well as Monoceras, Near the celestial equator, And southern constellations Pupus, Vela, Carina, Crux, Centaurus, Triangulum, Austrila, And aura. Polaris, Being the North Star, Is the approximate center of the northern celestial hemisphere. It is part of Ursa Minor, Constituting the end of the Little Dipper's handle. From latitudes of around 35 degrees north in January, Ursa Major containing the Big Dipper appears to the northeast. Ocassiopeia is the northwest. To the west are Pisces above the horizon and Aries. To the southwest, Cetus is near the horizon. Up high and to the south are Orion and Taurus. To the southeast above the horizon is Canis Major. Appearing above and to the east of Orion is Gemini. Also in the east and progressively closer to the horizon are Cancer and Leo. In addition to Taurus, Perseus and Auriga appear overhead. From the same latitude in July, Cassiopeia low in the sky, And Cepheus appear to the northeast. Ursa Major is now in the Northwest. Boötes is high up in the west. Virgo is to the west with Libra southwest, And Scorpius south. Sagittarius and Capricorn are southeast. Cygnus, Containing the northern cross, Is to the east. Hercules is high in the sky along with Corona Borealis. January constellations include Pictor and Reticulum, Near Hydras and Mensa respectively. In July, Aura, Adjacent to Triangula mostrella and Scorpius, Can be seen. Constellations near the Pole Star include Chameleon, Apis, And Triangulum Australa, Near Centaurus, Pavo, Hydrus, And Mensa. Sigma Octantis is the closest star approximating a southern pole star, But is faint in the night sky. Thus the pole can be triangulated using the constellation Crux, As well as the stars Alpha and Beta Centauri, About 30 degrees clockwise from Crux, Of the constellation Centaurus, Arching over Crux. It has been suggested that the 17, 000-year-old cave paintings in Lascaux, Southern France, Depict star constellations such as Taurus, Orion's belt, And the Pleiades. However, This view is not generally accepted among scientists. Inscribed stones and clay writing tablets from Mesopotamia and modern Iraq, Dating to 3000 BC, Provide the earliest generally accepted evidence for humankind's identification of constellations. It seems that the bulk of the Mesopotamian constellations were created within a relatively short interval, From around 1300 to 1000 BC. Mesopotamian constellations appear later in many of the classical Greek constellations. The oldest Babylonian catalogues of stars and constellations date back to the beginning of the Middle Bronze Age, Most notably the three stars each texts and the Molopin, An expanded and revised version based on more accurate observation from around 1000 BC. However, The numerous Sumerian names in these catalogs suggest that they built on older but otherwise unattested Sumerian traditions of the early Bronze Age. The Classic Zodiac is a revision of Neo-Babylonian constellations from the 6th century BC. The Greeks adopted the Babylonian constellations in the 4th century BC. 20 Ptolemaic constellations are from the ancient Near East. Another 10 have the same stars but different names. Biblical scholar E. W. Bollinger interpreted some of the creatures mentioned in the books of Ezekiel and Revelation as the middle signs of the four quarters of the zodiac, With the lion as Leo, The bull as Taurus, The man representing Aquarius, And the eagles standing in for Scorpio. The biblical book of Job also makes reference to a number of constellations, Including Eish, Beer, Chesil, Fool, Kima, Heap, Rendered as Arcturus, Orion, And Pleiades by the King James Version, But Eish, The Beer, Actually corresponding to Ursa Major. The term Masroth, Translated as a garland of crowns, Is a hapax legomenon in Job 38. 32, And it might refer to the zodiacal constellations. There is only limited information on ancient Greek constellations, With some fragmentary evidence being found in the works and days of the Greek poet Hesiod, Who mentioned the heavenly bodies. Greek astronomy essentially adopted the older Babylonian system in the Hellenistic era, First introduced to Greece by Eudoxus of Nidus in the 4th century BC. The original work of Eudoxus is lost, But it survives as a versification by Aretas dating to the 3rd century BC. The most complete existing works dealing with the mythical origins of the constellations are by the Hellenistic writer termed Pseudo-Arasthenes and an early Roman writer styled Pseudo-Hygienus. The basis of Western astronomy as taught during late antiquity and until the early modern period is the Almagist by Ptolemy, Written in the 2nd century. In the Ptolemaic kingdom, Native Egyptian tradition of anthropomorphic figures represented the planets, Stars, And various constellations. Some of these were combined with Greek and Babylonian astronomical systems, Culminating in the Zodiac of Dendera, The oldest known depiction of the Zodiac, Showing all the now familiar constellations, Along with some original Egyptian constellations, Deacons, And planets. It remains unclear when this occurred, But most were placed during the Roman period between 2nd to 4th centuries AD. Ptolemy's Almagest remained the standard definition of constellations in the medieval period, Both in Europe and in Islamic astronomy. Ancient China had a long tradition of observing celestial phenomena. Non-specific Chinese star names, Later categorized in the 28 mansions, Have been found on oracle bones from Anyang, Dating back to the Middle Xiong Dynasty. Chinese constellations are among the most significant observations of the Chinese sky, Dating back to the 5th century BCE. The Chinese system developed independently from the Greco-Roman system, Although there may have been earlier mutual influence, Suggested by parallels to ancient Babylonian astronomy. Three schools of classical Chinese astronomy in the Han period are attributed to astronomers of the earlier Warring States period. The constellations of the three schools were conflated into a single system by Chen Zuo, An astronomer of the 3rd century, The Three Kingdoms period. Chenzuo's work has been lost, But information on his system of constellations survives in Tang Dynasty records, Notably by Gautama Siddha in his Nine Caesars Canon, An Indo-Chinese resident of Chang'an. The oldest extant Chinese star chart dates to that period and was preserved as part of the Dunhuang manuscripts. Native Chinese astronomy flourished during the Song Dynasty, And during the Yuan Dynasty and the subsequent Ming Dynasty, Became increasingly influenced by other eastern and western astronomers of the medieval era. As maps were prepared during this period on more scientific lines, They were considered as more reliable. A well-known map from the Song period is a Suzhou astronomical chart, Which was prepared with carvings of stars on the planisphere of the Chinese sky on a stone plate. It is done accurately based on observations. And it shows the 1054 supernova in Taurus. Influenced by European astronomy during the late Ming dynasty, Charts depicted more stars but retained the traditional constellations. Newly observed stars were incorporated as supplementary to old constellations in the southern sky, Which did not depict the traditional stars recorded by ancient Chinese astronomers. Further improvements were made during the later part of the Ming dynasty by Su Guangqi and Johann Adam Schalf von Bell, The German Jesuit, And were recorded in Chengzhen Lixiu, Calendrical treatise of Chengzhen period 1628. Traditional Chinese star maps incorporated 23 new constellations with 125 stars of the southern hemisphere of the sky, Based on the knowledge of Western star charts. With this improvement, The Chinese sky was integrated with world astronomy. Historically, The origins of the constellations of the northern and southern skies are distinctly different. Most northern constellations date to antiquity, With names based mostly on classical Greek legends. Evidence of these constellations has survived in the form of star charts, Whose oldest representation appears on a statue known as the Farnese Atlas, Based perhaps on the star catalogue of the Greek astronomer Hipparchus. Southern constellations are more modern inventions, Sometimes as substitutes for ancient constellations. Some southern constellations had long names that were shortened to more usable forms. E. G. Musca Australis became simply Musca. Some of the early constellations were never universally adopted. Stars were often grouped into constellations differently by different observers, And the arbitrary constellation boundaries often led to confusion as to which constellation a celestial object belonged. Before astronomers delineated precise boundaries, Starting in the 19th century, Constellations generally appeared as ill-defined regions of the sky. Today they now follow officially accepted designated lines of right ascension and declination based on those defined by Benjamin Gould in Equinox B1875. 0 in his star catalogue Uranometria Argentina. The 1603 star atlas, Uranometria of Johann Baeyer, Assigned stars to individual constellations, And formalized the division by assigning a series of Greek and Latin letters to the stars within each constellation. These are known today as buyer designations. Subsequent star atlases led to the development of today's accepted modern constellations. Several modern proposals have not survived. The French astronomers Pierre Lemoyne and Joseph Lalonde, For example, Propose constellations that were once popular but have since been dropped. The northern constellation, Quadrans muralis, Survived into the 19th century, But is now divided between Boötes and Draco. In 1922, Henry Norris Russell produced a list of 88 constellations, With three-letter abbreviations for them. However, These constellations did not have clear borders between them. In 1928, The IAU formally accepted the 88 modern constellations with contiguous boundaries along vertical and horizontal lines of right ascension and declination, Developed by Eugene Delporte, That together cover the entire celestial sphere. This list was finally published in 1930. Where possible, These modern constellations usually share the names of their Greco-Roman predecessors, Such as Orion, Leo, Or Scorpius. The aim of this system is area mapping, I. E. , The division of the celestial sphere into contiguous fields. Of the 88 modern constellations, 36 lie predominantly in the northern sky and the other 52 predominantly in the southern. The boundaries developed by Delporte used data that originated back to epoch B1875. 0, Which was when Benjamin A. Gould first made his proposal to designate boundaries for the celestial sphere, A suggestion on which Delporte based his work. The consequence of this early date is that because of the precession of the equinoxes, The borders on a modern star map, Such as Epic J2000, Are already somewhat skewed and no longer perfectly vertical or horizontal. This effect will increase over the years and centuries to come. The constellations have no official symbols, Though those of the ecliptic may take the signs of the zodiac. Symbols for the other modern constellations, As well as the older ones that still occur in modern nomenclature, Have occasionally been published. The Great Rift, A series of dark patches in the Milky Way, Is most visible in the southern sky. Members of the Inca civilization identified various dark areas or dark nebulae in the Milky Way as animals and associated their appearance with the seasonal rains. Australian Aboriginal astronomy also describes dark cloud constellations, The most famous being the emu in the sky, Whose head is formed from the coal sack, A dark nebula instead of the stars.

Reviews

Made me think fondly of a favorite childhood book about stars and constellations. And also the first time I was in the Colorado Rockies and saw the clearest, brightest starlit night sky! Something I hadn’t witnessed growing up in the SF Bayarea. Thanks Benjamin, another good’n!

I've never been very interested in constellations, but this was a fascinating podcast. I stayed awake for much of it, although I drifted off to sleep several times. Thank you so much for posting this podcast.