|
Bya
bya or b.y.a. is an abbreviation for "billion years ago". It is commonly used as a unit of time to denote length of time before the present in 109 years. This initialism is often used in the sciences of astronomy, geology, and paleontology. The "billion" in bya is the 109 "billion" of the short scale of the U.S.,Gale, Joseph (2009). ''Astrobiology of Earth: The Emergence''. Oxford: Oxford University Press, p21./ref> not the long-scale 1012 "billion" of some European usage. Billion by this convention (109) is often called a "thousand million" in the UK and a "milliard" in some other countries.Chartrand, Mark (2004). ''Satellite Communications for the Nonspecialist''. New York: SPIE Press, p73./ref> For this reason, there is potential for some confusion, and some scientists prefer the unit Gya, while others prefer Ga (Giga-annum), however, bya remains in more widespread use. In 1974, the UK switched from the long scale to the short scale. Related units are mya ("million years ag ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Giga-annum
A year is a unit of time based on how long it takes the Earth to orbit the Sun. In scientific use, the tropical year (approximately 365 solar days, 5 hours, 48 minutes, 45 seconds) and the sidereal year (about 20 minutes longer) are more exact. The modern calendar year, as reckoned according to the Gregorian calendar, approximates the tropical year by using a system of leap years. The term 'year' is also used to indicate other periods of roughly similar duration, such as the lunar year (a roughly 354-day cycle of twelve of the Moon's phasessee lunar calendar), as well as periods loosely associated with the calendar or astronomical year, such as the seasonal year, the fiscal year, the academic year, etc. Due to the Earth's axial tilt, the course of a year sees the passing of the seasons, marked by changes in weather, the hours of daylight, and, consequently, vegetation and soil fertility. In temperate and subpolar regions around the planet, four seasons are generally recogn ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Europe
Europe is a continent located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south, and Asia to the east. Europe shares the landmass of Eurasia with Asia, and of Afro-Eurasia with both Africa and Asia. Europe is commonly considered to be Boundaries between the continents#Asia and Europe, separated from Asia by the Drainage divide, watershed of the Ural Mountains, the Ural (river), Ural River, the Caspian Sea, the Greater Caucasus, the Black Sea, and the waterway of the Bosporus, Bosporus Strait. "Europe" (pp. 68–69); "Asia" (pp. 90–91): "A commonly accepted division between Asia and Europe ... is formed by the Ural Mountains, Ural River, Caspian Sea, Caucasus Mountains, and the Black Sea with its outlets, the Bosporus and Dardanelles." Europe covers approx. , or 2% of Earth#Surface, Earth's surface (6.8% of Earth's land area), making it ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Long And Short Scales
The long and short scales are two power of 10, powers of ten number naming systems that are consistent with each other for smaller order of magnitude, numbers, but are contradictory for larger numbers. Other numbering systems, particularly in East Asia and South Asia, have large number naming that differs from both the long and short scales. Such numbering systems include the Indian numbering system and Chinese numerals, Chinese, Japanese numerals#Powers of 10, Japanese, and Korean Peninsula, Korean numerals. Much of the remainder of the world adopted either the short or long scale. Countries using the long scale include most countries in continental Europe and most that are Geographical distribution of French speakers, French-speaking, Geographical distribution of German speakers, German-speaking and Hispanophone, Spanish-speaking. Use of the short scale is found in most Anglophone, English and Arabic speaking countries, most Eurasian post-communist countries and Brazil. F ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Abbreviation
An abbreviation () is a shortened form of a word or phrase, by any method including shortening (linguistics), shortening, contraction (grammar), contraction, initialism (which includes acronym), or crasis. An abbreviation may be a shortened form of a word, usually ended with a trailing period. For example, the term ''etc.'' is the usual abbreviation for the list of Latin phrases, Latin phrase . Types A ''Contraction (grammar), contraction'' is an abbreviation formed by replacing letters with an apostrophe. Examples include ''I'm'' for ''I am'' and ''li'l'' for ''little''. An ''initialism'' or ''acronym'' is an abbreviation consisting of the initial letter of a sequence of words without other punctuation. For example, Federal Bureau of Investigation, FBI (wiktionary:FBI#Pronunciation, ), United States, USA (wiktionary:USA#Pronunciation, ), IBM (wiktionary:IBM#Pronunciation, ), BBC (wiktionary:BBC#Pronunciation, ). When initialism is used as the preferred term, acronym refers mor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Before Present
Before Present (BP) or "years before present (YBP)" is a time scale used mainly in archaeology, geology, and other scientific disciplines to specify when events occurred relative to the origin of practical radiocarbon dating in the 1950s. Because the "present" time changes, standard practice is to use 1January 1950 as the commencement date (epoch) of the age scale, with 1950 being labelled as the "standard year". The abbreviation "BP" has been interpreted retrospectively as "Before Physics", which refers to the time before nuclear weapons testing artificially altered the proportion of the carbon isotopes in the atmosphere, which scientists must account for when using radiocarbon dating for dates of origin that may fall after this year. In a convention that is not always observed, many sources restrict the use of BP dates to those produced with radiocarbon dating; the alternative notation "RCYBP" stands for the explicit "radio carbon years before present". Usage The BP scale is s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chronology
Chronology (from Latin , from Ancient Greek , , ; and , ''wikt:-logia, -logia'') is the science of arranging events in their order of occurrence in time. Consider, for example, the use of a timeline or sequence of events. It is also "the determination of the actual temporal sequence of past events".Memidex/WordNet, "chronology,memidex.com (accessed September 25, 2010). Chronology is a part of periodization. It is also a part of the discipline of history including earth history, the earth sciences, and study of the geologic time scale. Related fields Chronology is the science of locating historical events in time. It relies mostly upon chronometry, which is also known as timekeeping, and historiography, which examines the writing of history and the use of historical methods. Radiocarbon dating estimates the age of formerly living things by measuring the proportion of carbon-14 isotope in their carbon content. Dendrochronology estimates the age of trees by correlation of the var ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Capitalization
Capitalization ( North American spelling; also British spelling in Oxford) or capitalisation (Commonwealth English; all other meanings) is writing a word with its first letter as a capital letter (uppercase letter) and the remaining letters in lower case, in writing systems with a case distinction. The term also may refer to the choice of the casing applied to text. Conventional writing systems ( orthographies) for different languages have different conventions for capitalization, for example, the capitalization of titles. Conventions also vary, to a lesser extent, between different style guides. In addition to the Latin script, capitalization also affects the Armenian, Cyrillic, Georgian and Greek alphabets. The full rules of capitalization in English are complicated. The rules have also changed over time, generally to capitalize fewer words. The conventions used in an 18th-century document will be unfamiliar to a modern reader; for instance, many common nouns were capital ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lowercase
Letter case is the distinction between the letters that are in larger uppercase or capitals (more formally ''majuscule'') and smaller lowercase (more formally '' minuscule'') in the written representation of certain languages. The writing systems that distinguish between the upper- and lowercase have two parallel sets of letters: each in the majuscule set has a counterpart in the minuscule set. Some counterpart letters have the same shape, and differ only in size (e.g. ), but for others the shapes are different (e.g., ). The two case variants are alternative representations of the same letter: they have the same name and pronunciation and are typically treated identically when sorting in alphabetical order. Letter case is generally applied in a mixed-case fashion, with both upper and lowercase letters appearing in a given piece of text for legibility. The choice of case is often denoted by the grammar of a language or by the conventions of a particular discipline. In ortho ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mya (unit)
Mya or MYA may refer to: Brands and product names * Mya (TV channel), an Italian Television channel * Mya (program), an intelligent personal assistant created by Motorola * Midwest Young Artists, a comprehensive youth music program Codes * Burmese language (ISO 639-3: ) * Moruya Airport (IATA code: MYA), New South Wales, Australia * The IOC, license plate, and UNDP country code for Myanmar Myanmar, officially the Republic of the Union of Myanmar; and also referred to as Burma (the official English name until 1989), is a country in northwest Southeast Asia. It is the largest country by area in Mainland Southeast Asia and has ... People * Mya (given name) * Mya (singer) (Mya Marie Harrison, born 1979), American R&B singer-songwriter and actress * Bo Mya (1927–2006), Myanmar rebel leader and chief commander of the Karen National Union Other uses * ''Mýa'' (album), a 1998 album by Mýa * ''Mya'' (bivalve), a genus of soft-shell clams * Million years a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
United States
The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 contiguous states border Canada to the north and Mexico to the south, with the semi-exclave of Alaska in the northwest and the archipelago of Hawaii in the Pacific Ocean. The United States asserts sovereignty over five Territories of the United States, major island territories and United States Minor Outlying Islands, various uninhabited islands in Oceania and the Caribbean. It is a megadiverse country, with the world's List of countries and dependencies by area, third-largest land area and List of countries and dependencies by population, third-largest population, exceeding 340 million. Its three Metropolitan statistical areas by population, largest metropolitan areas are New York metropolitan area, New York, Greater Los Angeles, Los Angel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1000000000 (number)
1,000,000,000 (one billion, long and short scale, short scale; one thousand million or one milliard, one yard, Long and short scales, long scale) is the natural number following 100,000,000#900,000,000 to 999,999,999, 999,999,999 and preceding 1,000,000,001. With a number, "billion" can be abbreviated as b, bil or bn. In standard form, it is written as 1 × 109. The metric prefix giga indicates 1,000,000,000 times the base unit. Its symbol is Giga-, G. One billion years may be called an ''aeon, eon'' in astronomy or geology. Previously in British English (but not in Comparison of American and British English#Numbers, American English), the word "billion" referred exclusively to a Trillion, million millions (1,000,000,000,000). However, this is not common anymore, and the word has been used to mean one thousand million (1,000,000,000) for several decades. The term ''milliard'' could also be used to refer to 1,000,000,000; whereas "milliard" is rarely used in English, variations ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paleontology
Paleontology, also spelled as palaeontology or palæontology, is the scientific study of the life of the past, mainly but not exclusively through the study of fossils. Paleontologists use fossils as a means to classify organisms, measure geologic time, and assess the interactions between prehistoric organisms and their natural environment. While paleontological observations are known from at least the 6th century BC, the foundation of paleontology as a science dates back to the work of Georges Cuvier in 1796. Cuvier demonstrated evidence for the concept of extinction and how life of the past was not necessarily the same as that of the present. The field developed rapidly over the course of the following decades, and the French word ''paléontologie'' was introduced for the study in 1822, which was derived from the Ancient Greek word for "ancient" and words describing relatedness and a field of study. Further advances in the field accompanied the work of Charles Darwin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
