KIC 12557548 History of detection[edit] The existence of the planet was first evidenced in data collected by the Kepler spacecraft. However, the light curve of the star, a graph of its stellar flux versus time, showed that while there were regular drops in stellar flux approximately every 15 hours, the amount of light being blocked covered a wide range, from 0.2% to 1.3% of the starlight being blocked.[2] Rappaport et al. (2012) proposed various possible phenomena which may have caused the anomalies in the light curve, including two planets orbiting each other,[6] and an eclipsing binary orbiting the star in a larger triple-star system.[2] However, the authors found the hypothetical binary planet system to be unstable[2] and the latter scenario to be poorly supported by the data collected by Kepler.[2] Planetary system[edit] References[edit] ^ Jump up to: a b c d e f "Basic data: 2MASS J19235189+5130170 -- Infra-Red source". Brogi, M.; Keller, C. Notes[edit] External links[edit]
Geological history of Earth Geologic time represented in a diagram called a geological clock, showing the relative lengths of the eons of Earth's history and noting major events The geological history of Earth follows the major events in Earth's past based on the geologic time scale, a system of chronological measurement based on the study of the planet's rock layers (stratigraphy). Earth formed about 4.54 billion years ago by accretion from the solar nebula, a disk-shaped mass of dust and gas left over from the formation of the Sun, which also created the rest of the Solar System. As the surface continually reshaped itself over hundreds of millions of years, continents formed and broke apart. The present pattern of ice ages began about 40 million years ago, then intensified at the end of the Pliocene. Precambrian[edit] The Precambrian includes approximately 90% of geologic time. Hadean Eon[edit] Archean Eon[edit] By 3.5 billion years ago, the Earth's magnetic field was established. Proterozoic Eon[edit]
10th millennium BC The 10th millennium BC marks the beginning of the Mesolithic and Epipaleolithic periods, which is the first part of the Holocene epoch. Agriculture, based on the cultivation of primitive forms of millet and rice, occurred in Southwest Asia.[1]Although agriculture was being developed in the Fertile Crescent, it would not be widely practised for another 2,000 years.[citation needed] Events[edit] c. 10,000 BC; First cave drawings of the Mesolithic period are made, with war scenes and religious scenes, *beginnings of what became story telling, and metamorphosed into acting. Old World[edit] Americas[edit] North America[edit] Australasia[edit] Australia[edit] Environmental changes[edit] c. 10,000 BC: c. 9700 BC: Lake Agassiz forms c. 9700 BC: Younger Dryas cold period ends. In popular culture[edit] Chronological studies[edit] [edit] Jump up ^ Roberts (1994)Jump up ^ "Historical Estimates of World Population". References[edit]
Future of the Earth Conjectured illustration of the scorched Earth after the Sun has entered the red giant phase, 7 billion years from now.[1] During the next four billion years, the luminosity of the Sun will steadily increase, resulting in a rise in the solar radiation reaching the Earth. This will cause a higher rate of weathering of silicate minerals, which will cause a decrease in the level of carbon dioxide in the atmosphere. In about 600 million years, the level of CO 2 will fall below the level needed to sustain C3 carbon fixation photosynthesis used by trees. Some plants use the C4 carbon fixation method, allowing them to persist at CO 2 concentrations as low as 10 parts per million. In about 1.1 billion years, the solar luminosity will be 10% higher than at present. Human influence[edit] There are multiple scenarios for known risks that can have a global impact on the planet. Should the human race become extinct, then the various features assembled by humanity will begin to decay. Glaciation[edit]
untitled signification des couleurs - Page 3 Signification de la couleur des pays du monde. (M) Alphabétisation par M. Le drapeau de la Macédoine : est composé d'un soleil jaune à 8 rayons sur un ciel rouge. Le drapeau de Madagascar :est ledrapeau national et le pavillon national de la République de Madagascar. Le drapeau de la Malaisie :est le drapeau civil, le drapeau d'État et pavillon d'État de la Malaisie. Le drapeau du Malawi :Adopté le29 juillet 2010 suite à la proposition faite par le Parti démocrate-progressiste au gouvernement malawite. Le drapeau des Maldives :est le drapeau national et le pavillon national de la République des Maldives. Le drapeau du Mali : Adopté le 1er mars 1961, composé de 3 bandes verticales et égales de couleur verte, or et rouge. Le drapeau de Malte :Est officiellement adopté en même temps que la constitution maltaise le 21 septembre 1964, jour de l'indépendance. Le drapeau du Maroc :est l’emblème du Royaume du Maroc. Le drapeau de Maurice : Adopté le 12 mars 1968 suite à l'indépendance du pays.
Holocene extinction The dodo, a flightless bird of Mauritius, became extinct during the mid-late seventeenth century after humans destroyed the forests where the birds made their homes and introduced mammals that ate their eggs. The Holocene extinction includes the disappearance of large mammals known as megafauna, starting between 9,000 and 13,000 years ago, the end of the last Ice Age. This may have been due to the extinction of the mammoth that had maintained grasslands that became birch forests without the mammoths.[3] The new forest and the resulting forest fires may have induced climate change.[3] Such disappearances might be the result of the proliferation of modern humans which led to climate change. These extinctions, occurring near the Pleistocene–Holocene boundary, are sometimes referred to as the Quaternary extinction event. The Holocene extinction continues into the 21st century. Prehistoric extinctions[edit] North and South America[edit] New Zealand[edit] Pacific, including Hawaii[edit]
untitled World Population Clock: 7 Billion People (2013) - Worldometers World Population: Past, Present, and Future (move and expand the bar at the bottom of the chart to navigate through time) The chart above illustrates how world population has changed throughout history. View the full tabulated data. At the dawn of agriculture, about 8000 B.C., the population of the world was approximately 5 million. A tremendous change occurred with the industrial revolution: whereas it had taken all of human history until around 1800 for world population to reach one billion, the second billion was achieved in only 130 years (1930), the third billion in 30 years (1960), the fourth billion in 15 years (1974), and the fifth billion in only 13 years (1987). During the 20th century alone, the population in the world has grown from 1.65 billion to 6 billion. Wonder how big was the world's population when you were born? Growth Rate Yearly Growth Rate (%) Annual growth rate reached its peak in the late 1960s, when it was at around 2%. World Population (2019 and historical) Jews
Ross 248 This star has about 12% of the Sun's mass and 16% of the Sun's radius, but only 0.2% of the Sun's luminosity. It has a stellar classification of M6 V,[3] which indicates it is a type of main sequence star known as a red dwarf. This is a flare star that occasionally increases in luminosity.[13] With high probability there appears to be a long-term cycle of variability with a period of 4.2 years. Long term observations of this star by the Sproul Observatory show no astrometric perturbations by an unseen companion.[15] The proper motion of this star was examined for a brown dwarf or stellar companion orbiting at a wide separation (between 100–1400 AU) but none was found.[16] A search for a faint companion using the Hubble Space Telescope Wide Field Planetary Camera revealed nothing,[7] nor did a search with near-infrared speckle interferometry.[17] However, none of these searches rule out a companion that is smaller than the detection minima. Field star[edit] See also[edit] References[edit]
untitled Tidal acceleration A picture of the Earth and the Moon from Mars. The presence of the moon (which has about 1/81 the mass of Earth), is slowing Earth's rotation and lengthening the day by about 2 ms every century. Tidal acceleration is an effect of the tidal forces between an orbiting natural satellite (e.g. the Moon), and the primary planet that it orbits (e.g. Earth). The similar process of tidal deceleration occurs for satellites that have an orbital period that is shorter than the primary's rotational period, or that orbit in a retrograde direction. The naming is somewhat confusing, because the actual speed of the satellite is decreased as a result of tidal acceleration, and increased as a result of tidal deceleration. Earth–Moon system[edit] Discovery history of the secular acceleration[edit] Edmond Halley was the first to suggest, in 1695,[1] that the mean motion of the Moon was apparently getting faster, by comparison with ancient eclipse observations, but he gave no data. Historical evidence[edit]
untitled Stability of the Solar System The stability of the Solar System is a subject of much inquiry in astronomy. Though the planets have been stable historically, and will be in the short term, their weak gravitational effects on one another can add up in unpredictable ways. For this reason (among others) the Solar System is stated to be chaotic,[1] and even the most precise long-term models for the orbital motion of the Solar System are not valid over more than a few tens of millions of years.[2] The Solar System is stable in human terms, in that none of the planets will collide with each other or be ejected from the system in the next few billion years,[3] and the Earth's orbit will be relatively stable.[4] Overview and challenges[edit] The orbits of the planets are open to long-term variations, and modeling the Solar System is subject to the n-body problem. Resonance[edit] Graph showing the numbers of Kuiper belt objects for a given distance (in AU) from the Sun Predictability[edit] Scenarios[edit] Jovian moon resonance[edit]