The Flamsteed designation for bright stars consists of a number and the genitive form of the constellation name. Another type of smaller popular patterns or groupings of stars are called asterisms , and differ from the modern or former constellations by being areas with identifiable shapes or features that can be used by novice observers learning to navigate the night sky.
Such asterisms often refer to several stars within a constellation or may share boundaries with several constellations. Examples of asterisms include: The Pleiades and The Hyades within the constellation of Taurus , the False Cross crossing the southern constellations of both Carina and Vela , or Venus' Mirror in the constellation of Orion.
For a porch light a 9 W lumen compact fluorescent lamp is more than adequate in most locations. Observations have been made of kestrels diurnal raptors hunting at night under the artihcial lights along motorways. A graduate of London University with a degree in philosophy, he teaches physics at a secondary school in London Here you will find all the products you need for taking successful astronomy photos: a large selection of cameras , suitable adapters and holders and optical aids such as field-flatteners, coma correctors, Bahtinov masks and much more. A fascinating exploration of the science of the impossible--from death rays and force fields to invisibility cloaks--revealing to what extent such technologies might be achievable decades or millennia into the future. Historically, the origins of the constellations of the northern and southern skies are distinctly different. Sky Atlas
A more modern astronomical sense of the term "constellation" is simply as a recognisable pattern of stars whose appearance is associated with mythological characters or creatures, or earthbound animals, or objects. Colloquial usage does not draw any sharp distinction between "constellations" or the many smaller "asterisms" pattern of stars , yet the modern accepted astronomical constellations employ such a distinction.
The southern False Cross asterism includes portions of the constellations Carina and Vela. The term circumpolar constellation is used for any constellation that, from a particular latitude on Earth, never sets below the horizon. From the North Pole or South Pole , all constellations south or north of the celestial equator are circumpolar constellations. Although stars in constellations appear near each other in the sky, they usually lie at a variety of distances away from the observer.
Since stars also travel along their own orbits through the Milky Way , the constellation outlines change slowly over time. After tens to hundreds of thousands of years, their familiar outlines gradually become unrecognisable. The earliest direct antecedent evidence for the constellations comes from inscribed stones and clay writing tablets dug up in Mesopotamia within modern Iraq dating back to BC.
These groupings appeared later in many of the classical Greek constellations. The Babylonians were the first to recognize that astronomical phenomena are periodic and apply mathematics to their predictions. However, the numerous Sumerian names in these catalogues suggest that they built on older, but otherwise unattested, Sumerian traditions of the Early Bronze Age. Knowledge of the Neo-Babylonian zodiac is also reflected in the Hebrew Bible. Bullinger interpreted the creatures appearing in the books of Ezekiel and thence in 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 Eagle standing in for Scorpio.
The Greeks adopted the Babylonian system in the 4th century BC. A total of twenty Ptolemaic constellations are directly continued from the Ancient Near East. Another ten have the same stars but different names. There is only limited information on indigenous Greek constellations, with some fragmentary evidence being found in the Works and Days of Greek poet Hesiod , who mentioned the "heavenly bodies".
The original work of Eudoxus is lost, but it survives as a versification by Aratus , 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-Eratosthenes and an early Roman writer styled pseudo- Hyginus. The basis of western astronomy as taught during Late Antiquity and until the Early Modern period is the Almagest by Ptolemy , written in the 2nd century. In the Ptolemaic Kingdom , native Egyptian tradition of anthropomorphic figures representing the planets, stars and various constellations.
The oldest known depiction of the zodiac showing all the now familiar constellations, along with some original Egyptian Constellations, Decans and Planets. In ancient China astronomy has had a long tradition in accurately observing celestial phenomena. These Chinese constellations are one of the most important and also the most ancient structures in the Chinese sky, attested from the 5th century BC.
Parallels to the earliest Babylonian Sumerian star catalogues suggest that the ancient Chinese system did not arise independently. Classical Chinese astronomy is recorded in the Han period and appears in the form of three schools, which are attributed to astronomers of the Warring States period. The constellations of the three schools were conflated into a single system by Chen Zhuo , an astronomer of the 3rd century Three Kingdoms period.
Chen Zhuo's work has been lost, but information on his system of constellations survives in Tang period records, notably by Qutan Xida. 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 became increasingly influenced by medieval Islamic astronomy see Treatise on Astrology of the Kaiyuan Era. A well known map prepared during the Song Period is the Suzhou Astronomical Chart prepared with carvings of most stars on the planisphere of the Chinese Sky on a stone plate; it is done accurately based on observations and has the supernova of the year of in Taurus carved on it.
Influenced by European astronomy during the late Ming Dynasty , more stars were depicted on the charts but retaining the traditional constellations; new stars observed were incorporated as supplementary stars in old constellations in the southern sky which did not depict any of the traditional stars recorded by ancient Chinese astronomers. Traditional Chinese star maps incorporated 23 new constellations with 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 the World astronomy.
Historically, the constellations can be simply divided into two regions; namely the northern and southern sky, whose origins are distinctly different. The northern skies have constellations that have mostly survived since Antiquity, whose common names are based on Classical Greek legends or those whose true origins have now been lost.
mag. Amplitude. mag. Amplitude. mag. 20h44m. 20h00m Bi 2. B Sh Crescent Nebula. Ced B Do Do vdB and span 18 by 12 inches. of these double-page charts cover the entire sky. Discover the best features of these top ten star atlases and how they can make Uranometria is a star atlas for dedicated observers. Uranometria contains double-page atlas charts, which regions whose scale has been magnified 2 to 3 times and that show stars to at least magnitude
Argo Navis. Some southern constellations were to become obsolete or had extended names that became foreshortened to more usable forms e.
Musca Australis became simply Musca. However, all the early constellations were never universally adopted, whose popular usage was based on the culture or individual nations.
Defining each constellation and their assigned stars also significantly differed in size and shape, whose arbitrary boundaries often lead to confusion to where celestial objects were to be placed. Before the constellation boundaries were defined by the International Astronomical Union IAU in , they appeared as simply encircled areas of sky. Since the invention of the optical telescope , astronomers have found the need to catalogue and position celestial bodies, whose knowledge could be used for navigational or astronomical purposes, and this required improved definitions of the constellations and their boundaries.
Such changes also assigned stars within each constellation, as first accomplished in by Johann Bayer in the star atlas " Uranometria " using the twenty-four letters of the Greek alphabet. However, much of the history of these origins were lost with the Destruction of the Library of Alexandria. During their long lifetimes, typically billions of years, stars create new elements from other, less complex ones.
For example, a solar-type star will create most of its energy from the continuous crushing together in the million-degree furnace of its core of vast numbers of hydrogen nuclei to make helium. Four hydrogen nuclei become one helium nucleus, a process which involves mass loss and the liberation of energy.
As a result of this relentless manufacture of helium, the Sun annihilates millions of tons of its mass every second, to be dispatched into space as energy in its various forms of electromagnetic radiation. Many of the other elements so familiar and vital to us on this planet, for exam- ple oxygen, silicon and carbon, were made by stars a little more massive than the Sun. The comparative scarcity, and resultant high price, of heavy elements such as gold - the International Gold Corporation estimates that all the gold in the world, mined and unmined, could be formed into an meter cube - stem from the fact that they are created during the final violent explosions of those rare stellar blast furnaces, the supernovae Fig.
These stars, ending their cosmically brief lives by rapidly ejecting nearly all their mass outwards into space, are hot enough to forge the heaviest of elements. Since there is, on average, only one supernova outburst every century in any one galaxy of a hundred billion stars, gold is in short supply in the universe. The most recent supernova visible to the unaided human eye was discovered on February 24, , about , years after its eruption in the Large Magellanic Starlight 27 N Fig. The once lowly tenth-magnitude star Sanduleak , suddenly the most famous object in the sky, eventually peaked as SNA at an apparent magnitude of h- 3.
The LMC is a satellite galaxy of the Milky Way, and the last naked-eye supernova inside our galaxy was recorded by Danish astronomer Tycho Brahe in We are well overdue for another.
The red giant star Betelgeuse, about light years dis- tant in Orion, is said to be worth watching. It may not have long to go, in stellar terms, before its final paroxysm. If humans observe this, it may well be visible in broad daylight and outshine the full Moon at night. Occasionally, an unexpected nova Fig. The nova will not have the eclat of a supernova, but may be bright enough for its progress to be monitored with the naked eye or with modest optical aid for a few days or weeks, finally disappearing again from view.
A clear view of the stars led, in ancient times, to their being grouped into con- stellations. Two thousand years ago, Ptolemy of Alexandria listed 48 constellations from former times. Today, 88 constellations mark out the heavens, serving as a convenient naming and reference system. It should be remembered that those con- stellations so familiar to European and American astronomers may baffle their 28 1 Living with Light Fig.
Altair is the brightest star at the top of the photo brethren in the Far East, for example, where completely different nomenclatures have evolved. Cave art at Lascaux in France suggests that, as far back 17, years ago, people were imagining pictures in the sky. About 5, years ago, the Sumerians and the Egyptians had already established their traceries of creatures, symbols and heroes in the sky Fig. On a clear night, with a simple chart and a good imagination, we can try to retrace the thoughts of the ancients as they found their way around the night sky, which served them as clock, compass, calendar and oracle, and as a scientific and religious primer.
The constellations have kept their identities over the millennia, and their number has gradually increased, facts that bear witness to the continuing fascination which the sight of the starry sky exerts over humans, and to our need to observe and interpret what we see in the environment above us. The Zodiacal Light 29 Fig. This manifests itself as a faintly glowing cone, slanting upwards from its base along the horizon, seen to the east shortly before dawn or to the west shortly after dusk Fig.
Only in a few dark places can it now be well observed. Brighter than parts of the Milky Way, it is best seen when the ecliptic, along which its axis lies, stands nearly vertical to the horizon in spring or autumn. This ghostly light is due to the scattering of sunlight by vast numbers of dust grains which litter the Solar System, many left behind by passing comets. Giovanni 30 1 Living with Light Fig. The particles involved are mostly between 0. This explains why the zodiacal light stretches along the ecliptic.
The Gegenschein In an extremely dark sky, such as might be seen nowadays only from locations remote from population centers, a faint circular glow may be perceived with the unaided eye in the night sky opposite the Sun the anti-solar point. Gegenschein is caused by the back-scattering of sunlight from tiny dust parti- cles. The French playwright Corneille testified to this in Le Cid, written in , long before the era of all-night artificial lighting.
The Gegenschein 31 Fig. It does not require much investigation to know why. Chapter 2 Light Pollution: The Problem Defined Lights and More Lights: The Rise of Artificial Illumination Since early humans sought the reassurance of their wood fires and tallow lamps many thousands of years ago, manmade light has been seen as our friend. It allowed its creators to see and perhaps frighten off the approaching predator, to go about their domestic business after sunset, and to paint images of great power and beauty in the silent fastness of caves.