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Tau Ceti
Tau Ceti, Latinized from τ Ceti, is a single star in the constellation Cetus that is spectrally similar to the Sun, although it has only about 78% of the Sun's mass. At a distance of just under from the Solar System, it is a relatively nearby star and the closest solitary G-class star. The star appears stable, with little stellar variation, and is metal-deficient relative to the Sun. It can be seen with the unaided eye with an apparent magnitude of 3.5. As seen from Tau Ceti, the Sun would be in the northern hemisphere constellation Boötes with an apparent magnitude of about 2.6.From Tau Ceti the Sun would appear on the diametrically opposite side of the sky at the coordinates RA = , Dec = , which is located near Tau Boötis. The absolute magnitude of the Sun is 4.8, so, at a distance of , the Sun would have an apparent magnitude m = M_v + 5 \cdot (\log_ 3.64 - 1) = 2.6. Observations have detected more than ten times as much dust surrounding ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cetus
Cetus () is a constellation, sometimes called 'the whale' in English. The Cetus (mythology), Cetus was a sea monster in Greek mythology which both Perseus and Heracles needed to slay. Cetus is in the region of the sky that contains other water-related constellations: Aquarius (constellation), Aquarius, Pisces (constellation), Pisces and Eridanus (constellation), Eridanus. Features Ecliptic Cetus is not among the 12 true zodiac constellations in the Epoch (astronomy), J2000 epoch, nor classical 12-part zodiac. The ecliptic passes less than 0.25° from one of its corners. Thus the moon and planets will enter Cetus (occulting any stars as a foreground object) in 50% of their successive orbits briefly and the southern part of the sun appears in Cetus for about one day each year. Many asteroids in belts have longer phases occulting the north-western part of Cetus, those with a slightly greater inclination to the ecliptic than the moon and planets. Astronomy on Mars#Celestial pole ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Habitable Zone
In astronomy and astrobiology, the circumstellar habitable zone (CHZ), or simply the habitable zone, is the range of orbits around a star within which a planetary surface can support liquid water given sufficient atmospheric pressure.J. F. Kasting, D. P. Whitmire, R. T. Reynolds, Icarus 101, 108 (1993). The bounds of the CHZ are based on Earth's position in the Solar System and the amount of radiant energy it receives from the Sun. Due to the importance of liquid water to Earth's biosphere, the nature of the CHZ and the objects within it may be instrumental in determining the scope and distribution of planets capable of supporting Earth-like extraterrestrial life and intelligence. The habitable zone is also called the Goldilocks zone, a metaphor, allusion and antonomasia of the children's fairy tale of "Goldilocks and the Three Bears", in which a little girl chooses from sets of three items, ignoring the ones that are too extreme (large or small, hot or cold, etc.), and settl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Latin
Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the Roman Republic it became the dominant language in the Italian region and subsequently throughout the Roman Empire. Even after the fall of Western Rome, Latin remained the common language of international communication, science, scholarship and academia in Europe until well into the 18th century, when other regional vernaculars (including its own descendants, the Romance languages) supplanted it in common academic and political usage, and it eventually became a dead language in the modern linguistic definition. Latin is a highly inflected language, with three distinct genders (masculine, feminine, and neuter), six or seven noun cases (nominative, accusative, genitive, dative, ablative, and vocative), five declensions, four verb conjuga ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cairo
Cairo ( ; ar, القاهرة, al-Qāhirah, ) is the capital of Egypt and its largest city, home to 10 million people. It is also part of the largest urban agglomeration in Africa, the Arab world and the Middle East: The Greater Cairo metropolitan area, with a population of 21.9 million, is the 12th-largest in the world by population. Cairo is associated with ancient Egypt, as the Giza pyramid complex and the ancient cities of Memphis and Heliopolis are located in its geographical area. Located near the Nile Delta, the city first developed as Fustat, a settlement founded after the Muslim conquest of Egypt in 640 next to an existing ancient Roman fortress, Babylon. Under the Fatimid dynasty a new city, ''al-Qāhirah'', was founded nearby in 969. It later superseded Fustat as the main urban centre during the Ayyubid and Mamluk periods (12th–16th centuries). Cairo has long been a centre of the region's political and cultural life, and is titled "the city of a thousand m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Al Achsasi Al Mouakket
Muḥammad al-Akhṣāṣī al-Muwaqqit ( ar, محمد الاخصاصي الموقت) was an Egyptian astronomer whose and catalogue of stars, ('Pearls of brilliance upon the solar operations'), was written at Cairo about 1650. Al-Akhsasi was a shaykh, a learned elder, of the Grand Mosque of the university of Cairo, where his name ''al- Muwaqqit'' reflected his position regulating the times and hours at the mosque. His name Akhsasi connects him in origin to a village in the Faiyum, southwest of Cairo. No copies of his book were known to Western astronomers or historians of science The history of science covers the development of science from ancient times to the present. It encompasses all three major branches of science: natural, social, and formal. Science's earliest roots can be traced to Ancient Egypt and Mesop ... until 1895;Knobel 1895. thus he did not appear in the standard French and English bibliographies and library catalogues of the 19th century. Notes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Uranometria
''Uranometria'' is a star atlas produced by Johann Bayer. It was published in Augsburg in 1603 by Christoph Mangle (''Christophorus Mangus'') under the full title ''Uranometria: omnium asterismorum continens schemata, nova methodo delineata, aereis laminis expressa''. This translates to "Uranometria, containing charts of all the constellations, drawn by a new method and engraved on copper plates". The word "Uranometria" derives from Urania, muse of the heavens and "uranos" (''oυρανός'') the Greek word for sky / heavens. A literal translation of "Uranometria" is "Measuring the Heavens" (to be compared with "Geometry"—''"Geometria"'' in Greek, literally translated to "Measuring the Earth"). It was the first atlas to cover the entire celestial sphere. Charts ''Uranometria'' contained 51 star charts, engraved on copper plates by Alexander Mair ( 1562–1617). The first 48 charts illustrate each of the 48 Ptolemaic constellations. The 49th chart introduces 12 new constell ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Johann Bayer
Johann Bayer (1572 – 7 March 1625) was a German lawyer and uranographer (celestial cartographer). He was born in Rain, Lower Bavaria, in 1572. At twenty, in 1592 he began his study of philosophy and law at the University of Ingolstadt, after which he moved to Augsburg to begin work as a lawyer, becoming legal adviser to the city council in 1612. Bayer had several interests outside his work, including archaeology and mathematics. However, he is primarily known for his work in astronomy; particularly for his work on determining the positions of objects on the celestial sphere. He remained unmarried and died in 1625. Bayer's star atlas '' Uranometria Omnium Asterismorum'' (" Uranometry of all the asterisms") was first published in 1603 in Augsburg and dedicated to two prominent local citizens. This was the first atlas to cover the entire celestial sphere. It was based upon the work of Tycho Brahe and may have borrowed from Alessandro Piccolomini's 1540 star atlas, ''De le ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bayer Designation
A Bayer designation is a stellar designation in which a specific star is identified by a Greek or Latin letter followed by the genitive form of its parent constellation's Latin name. The original list of Bayer designations contained 1,564 stars. The brighter stars were assigned their first systematic names by the German astronomer Johann Bayer in 1603, in his star atlas ''Uranometria''. Bayer catalogued only a few stars too far south to be seen from Germany, but later astronomers (including Nicolas-Louis de Lacaille and Benjamin Apthorp Gould) supplemented Bayer's catalog with entries for southern constellations. Scheme Bayer assigned a lowercase Greek letter (alpha (α), beta (β), gamma (γ), etc.) or a Latin letter (A, b, c, etc.) to each star he catalogued, combined with the Latin name of the star's parent constellation in genitive (possessive) form. The constellation name is frequently abbreviated to a standard three-letter form. For example, Aldebaran in the constellation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Science Fiction
Science fiction (sometimes shortened to Sci-Fi or SF) is a genre of speculative fiction which typically deals with imaginative and futuristic concepts such as advanced science and technology, space exploration, time travel, parallel universes, extraterrestrial life, sentient artificial intelligence, cybernetics, certain forms of immortality (like mind uploading), and the singularity. Science fiction predicted several existing inventions, such as the atomic bomb, robots, and borazon, whose names entirely match their fictional predecessors. In addition, science fiction might serve as an outlet to facilitate future scientific and technological innovations. Science fiction can trace its roots to ancient mythology. It is also related to fantasy, horror, and superhero fiction and contains many subgenres. Its exact definition has long been disputed among authors, critics, scholars, and readers. Science fiction, in literature, film, television, and other media, has beco ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SETI
The search for extraterrestrial intelligence (SETI) is a collective term for scientific searches for intelligent extraterrestrial life, for example, monitoring electromagnetic radiation for signs of transmissions from civilizations on other planets. Scientific investigation began shortly after the advent of radio in the early 1900s, and focused international efforts have been ongoing since the 1980s. In 2015, Stephen Hawking and Israeli billionaire Yuri Milner announced a project called Breakthrough Listen. History Early work There have been many earlier searches for extraterrestrial intelligence within the Solar System. In 1896, Nikola Tesla suggested that an extreme version of his wireless electrical transmission system could be used to contact beings on Mars. In 1899, while conducting experiments at his Colorado Springs experimental station, he thought he had detected a signal from Mars since an odd repetitive static signal seemed to cut off when Mars set in the night ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Solar Analog
Solar-type star, solar analogs (also analogues), and solar twins are stars that are particularly similar to the Sun. The stellar classification is a hierarchy with solar twin being most like the Sun followed by solar analog and then solar-type. Observations of these stars are important for understanding better the properties of the Sun in relation to other stars and the habitability of planets. By similarity to the Sun Defining the three categories by their similarity to the Sun reflects the evolution of astronomical observational techniques. Originally, solar-type was the closest that similarity to the Sun could be defined. Later, more precise measurement techniques and improved observatories allowed for greater precision of key details like temperature, enabling the creation of a solar analog category for stars that were particularly similar to the Sun. Later still, continued improvements in precision allowed for the creation of a solar-twin category for near-perfect matche ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Planetary Habitability
Planetary habitability is the measure of a planet's or a natural satellite's potential to develop and maintain environments hospitable to life. Life may be generated directly on a planet or satellite endogenously or be transferred to it from another body, through a hypothetical process known as panspermia. Environments do not need to contain life to be considered habitable nor are accepted habitable zones (HZ) the only areas in which life might arise. As the existence of life beyond Earth is unknown, planetary habitability is largely an extrapolation of conditions on Earth and the characteristics of the Sun and Solar System which appear favorable to life's flourishing. Of particular interest are those factors that have sustained complex, multicellular organisms on Earth and not just simpler, unicellular creatures. Research and theory in this regard is a component of a number of natural sciences, such as astronomy, planetary science and the emerging discipline of astrobio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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