In astronomy, a rubble pile is a celestial body, not a monolith, consisting instead of numerous pieces of rock that have coalesced under the influence of gravity. Rubble piles have low density because there are large cavities between the various chunks that make them up. Asteroids Bennu and Ryugu have a measured bulk density which suggests a rubble pile internal structure. Many comets and most smaller minor planets are thought to be composed of coalesced rubble. Most smaller asteroids are thought to be rubble piles. A close analogy to a rubble pile is a melted shot and wax slug projectile fired from a shotgun as opposed to a monolithic pure lead slug, with the former having a lower density as it is loosely held together by wax and is composed of numerous individual lead bird shot spheres. Rubble piles form when an asteroid or moon is smashed to pieces by an impact, the shattered pieces subsequently fall back together due to self-gravitation; this coalescing takes from several hours to weeks. When a rubble-pile asteroid passes a much more massive object, tidal forces change its shape.
Scientists first suspected that asteroids are rubble piles when asteroid densities were first determined. Many of the calculated densities were less than those of meteorites, which in some cases had been determined to be pieces of asteroids. Many asteroids with low densities are thought to be rubble piles, for example 253 Mathilde; the mass of Mathilde, as determined by the NEAR Shoemaker mission, is far too low for the volume observed, considering the surface is rock. Ice with a thin crust of rock would not provide a suitable density; the large impact craters on Mathilde would have shattered a rigid body. However, the first unambiguous rubble pile to be photographed is 25143 Itokawa, which has no obvious impact craters and is thus certainly a coalescence of shattered fragments; the asteroid 433 Eros, the primary destination of NEAR Shoemaker, was determined to be riven with cracks but otherwise solid. Other asteroids including Itokawa, have been found to be contact binaries, two major bodies touching, with or without rubble filling the boundary.
Large interior voids are possible because of the low gravity of most asteroids. Despite a fine regolith on the outside, the asteroid's gravity is so weak that friction between fragments dominates and prevents small pieces from falling inwards and filling up the voids. All the largest asteroids are solid objects without any macroscopic internal porosity; this may be because they have been large enough to withstand all impacts, have never been shattered. Alternatively and some few other of the largest asteroids may be massive enough that if they were shattered but not dispersed, their gravity would collapse most voids upon recoalescing. Vesta, at least, has withstood intact one major impact since its formation and shows signs of internal structure from differentiation in the resultant crater that assures that it is not a rubble pile; this serves as evidence for size as a protection from shattering into rubble. Observational evidence suggest that the cometary nucleus may not be a well-consolidated single body, but may instead be a loosely bound agglomeration of smaller fragments, weakly bonded and subject to occasional or frequent disruptive events, although the larger cometary fragments are expected to be primordial condensations rather than collisionally derived debris as in the asteroid case.
However, in situ observations by the Rosetta mission, indicates that it may be more complex than that. The moon Phobos, the larger of the two natural satellites of the planet Mars, is thought to be a rubble pile bound together by a thin regolith crust about 100 m thick. Spectroscopy of Phobos' composition suggests. Comet nucleus List of slow rotators Close-up images of Itokawa, a rubble pile asteroid NASA Astronomy Picture of the Day: Saturn's Moon Calypso, another possible rubble pile Hyper-Velocity Impacts on Rubble Pile Asteroids pdf online @ kent.ac.uk
A minor-planet moon is an astronomical object that orbits a minor planet as its natural satellite. As of February 2019, there are 352 minor planets suspected to have moons. Discoveries of minor-planet moons are important because the determination of their orbits provides estimates on the mass and density of the primary, allowing insights of their physical properties, not otherwise possible; the first modern era mention of the possibility of an asteroid satellite was in connection with an occultation of the bright star Gamma Ceti by the asteroid 6 Hebe in 1977. The observer, amateur astronomer Paul D. Maley, detected an unmistakable 0.5 second disappearance of this naked eye star from a site near Victoria, Texas. Many hours several observations were reported in Mexico attributed to the occultation by 6 Hebe itself. Although not confirmed, this documents the first formally documented case of a suspected companion of an asteroid. In addition to the terms satellite and moon, the term "binary" is sometimes used for minor planets with moons, "triple" for minor planets with two moons.
If one object is much bigger it can be referred to as the primary and its companion as secondary. The term double asteroid is sometimes used for systems in which the asteroid and its moon are the same size, while binary tends to be used independently from the relative sizes of the components; when binary minor planets are similar in size, the Minor Planet Center refers to them as "binary companions" instead of referring to the smaller body as a satellite. A good example of a true binary is the 90 Antiope system, identified in August 2000. Small satellites are referred to as moonlets. Prior to the era of the Hubble Space Telescope and space probes reaching the outer Solar System, attempts to detect satellites around asteroids were limited to optical observations from Earth. For example, in 1978, stellar occultation observations were claimed as evidence of a satellite for the asteroid 532 Herculina; however more-detailed imaging by the Hubble Telescope did not reveal a satellite, the current consensus is that Herculina does not have a significant satellite.
There were other similar reports of asteroids having companions in the following years. A letter in Sky & Telescope magazine at this time pointed to simultaneous impact craters on Earth, suggesting that these craters were caused by pairs of gravitationally bound objects. In 1993, the first asteroid moon was confirmed when the Galileo probe discovered the small Dactyl orbiting 243 Ida in the asteroid belt; the second was discovered around 45 Eugenia in 1998. In 2001, 617 Patroclus and its same-sized companion Menoetius became the first known binary asteroids in the Jupiter trojans; the first trans-Neptunian binary after Pluto–Charon, 1998 WW31, was optically resolved in 2002. Triple or trinary minor planets, are known since 2005, when the asteroid 87 Sylvia was discovered to have two satellites, making it the first known triple system; this was followed by the discovery of a second moon orbiting 45 Eugenia. In 2005, the dwarf planet Haumea was discovered to have two moons, making it the second trans-Neptunian object after Pluto known to have more than one moon.
Additionally, 216 Kleopatra and 93 Minerva were discovered to be trinary asteroids in 2008 and 2009 respectively. Since the first few triple minor planets were discovered, more continue to be discovered at a rate of about one a year. Most discovered were two moons orbiting large near-earth asteroid 3122 Florence, bringing the number of known trinary systems in the Solar System up to 14; the following table lists all satellites of triple systems chronologically by their discovery date, starting with Charon, discovered in 1978. The data about the populations of binary objects are still patchy. In addition to the inevitable observational bias the frequency appears to be different among different categories of objects. Among asteroids, an estimated 2% would have satellites. Among trans-Neptunian objects, an estimated 11% are thought to be binary or multiple objects, the majority of the large TNOs have at least one satellite, including all four IAU-listed dwarf planets. More than 50 binaries are known in each of the main groupings: near-Earth asteroids, belt asteroids, trans-Neptunian objects, not including numerous claims based on light-curve variation.
Two binaries have been found so far among centaurs with semi-major axes smaller than Neptune. Both are double ring systems around 2060 Chiron and 10199 Chariklo, discovered in 1994–2011 and 2013 respectively; the origin of minor-planet moons is not known with certainty, a variety of theories exist. A accepted theory is that minor-planet moons are formed from debris knocked off of the primary by an impact. Other pairings may be formed. Formation by collision is constrained by the angular momentum of the components, i.e. by the masses and their separation. Close binaries fit this model. Distant binaries however, with components of comparable size, are unlikely to have followed this scenario, unless considerable mass has been lost in the event; the distances of the components for the known binaries vary from a few hundreds of kilometres to more than 3000 km for the asteroids. Among TNOs, the known separations vary from 3,000 to 50,000 km. What is "typical" for a binary system tends to depend on its location in the Solar System (presumably because of different modes
Mass is both a property of a physical body and a measure of its resistance to acceleration when a net force is applied. The object's mass determines the strength of its gravitational attraction to other bodies; the basic SI unit of mass is the kilogram. In physics, mass is not the same as weight though mass is determined by measuring the object's weight using a spring scale, rather than balance scale comparing it directly with known masses. An object on the Moon would weigh less than it does on Earth because of the lower gravity, but it would still have the same mass; this is because weight is a force, while mass is the property that determines the strength of this force. There are several distinct phenomena. Although some theorists have speculated that some of these phenomena could be independent of each other, current experiments have found no difference in results regardless of how it is measured: Inertial mass measures an object's resistance to being accelerated by a force. Active gravitational mass measures the gravitational force exerted by an object.
Passive gravitational mass measures the gravitational force exerted on an object in a known gravitational field. The mass of an object determines its acceleration in the presence of an applied force; the inertia and the inertial mass describe the same properties of physical bodies at the qualitative and quantitative level by other words, the mass quantitatively describes the inertia. According to Newton's second law of motion, if a body of fixed mass m is subjected to a single force F, its acceleration a is given by F/m. A body's mass determines the degree to which it generates or is affected by a gravitational field. If a first body of mass mA is placed at a distance r from a second body of mass mB, each body is subject to an attractive force Fg = GmAmB/r2, where G = 6.67×10−11 N kg−2 m2 is the "universal gravitational constant". This is sometimes referred to as gravitational mass. Repeated experiments since the 17th century have demonstrated that inertial and gravitational mass are identical.
The standard International System of Units unit of mass is the kilogram. The kilogram is 1000 grams, first defined in 1795 as one cubic decimeter of water at the melting point of ice. However, because precise measurement of a decimeter of water at the proper temperature and pressure was difficult, in 1889 the kilogram was redefined as the mass of the international prototype kilogram of cast iron, thus became independent of the meter and the properties of water. However, the mass of the international prototype and its identical national copies have been found to be drifting over time, it is expected that the re-definition of the kilogram and several other units will occur on May 20, 2019, following a final vote by the CGPM in November 2018. The new definition will use only invariant quantities of nature: the speed of light, the caesium hyperfine frequency, the Planck constant. Other units are accepted for use in SI: the tonne is equal to 1000 kg. the electronvolt is a unit of energy, but because of the mass–energy equivalence it can be converted to a unit of mass, is used like one.
In this context, the mass has units of eV/c2. The electronvolt and its multiples, such as the MeV, are used in particle physics; the atomic mass unit is 1/12 of the mass of a carbon-12 atom 1.66×10−27 kg. The atomic mass unit is convenient for expressing the masses of molecules. Outside the SI system, other units of mass include: the slug is an Imperial unit of mass; the pound is a unit of both mass and force, used in the United States. In scientific contexts where pound and pound need to be distinguished, SI units are used instead; the Planck mass is the maximum mass of point particles. It is used in particle physics; the solar mass is defined as the mass of the Sun. It is used in astronomy to compare large masses such as stars or galaxies; the mass of a small particle may be identified by its inverse Compton wavelength. The mass of a large star or black hole may be identified with its Schwarzschild radius. In physical science, one may distinguish conceptually between at least seven different aspects of mass, or seven physical notions that involve the concept of mass.
Every experiment to date has shown these seven values to be proportional, in some cases equal, this proportionality gives rise to the abstract concept of mass. There are a number of ways mass can be measured or operationally defined: Inertial mass is a measure of an object's resistance to acceleration when a force is applied, it is determined by applying a force to an object and measuring the acceleration that results from that force. An object with small inertial mass will accelerate more than an object with large inertial mass when acted upon by the same force. One says. Active gravitational mass is a measure of the strength of an object's gravitational flux. Gravitational field can be measured by allowing a small "test object" to fall and measuring its free-fall acceleration. For example, an object in free fall near the Moon is subject to a smaller gravitational field, hence
The term apsis refers to an extreme point in the orbit of an object. It denotes either the respective distance of the bodies; the word comes via Latin from Greek, there denoting a whole orbit, is cognate with apse. Except for the theoretical possibility of one common circular orbit for two bodies of equal mass at diametral positions, there are two apsides for any elliptic orbit, named with the prefixes peri- and ap-/apo-, added in reference to the body being orbited. All periodic orbits are, according to Newton's Laws of motion, ellipses: either the two individual ellipses of both bodies, with the center of mass of this two-body system at the one common focus of the ellipses, or the orbital ellipses, with one body taken as fixed at one focus, the other body orbiting this focus. All these ellipses share a straight line, the line of apsides, that contains their major axes, the foci, the vertices, thus the periapsis and the apoapsis; the major axis of the orbital ellipse is the distance of the apsides, when taken as points on the orbit, or their sum, when taken as distances.
The major axes of the individual ellipses around the barycenter the contributions to the major axis of the orbital ellipses are inverse proportional to the masses of the bodies, i.e. a bigger mass implies a smaller axis/contribution. Only when one mass is sufficiently larger than the other, the individual ellipse of the smaller body around the barycenter comprises the individual ellipse of the larger body as shown in the second figure. For remarkable asymmetry, the barycenter of the two bodies may lie well within the bigger body, e.g. the Earth–Moon barycenter is about 75% of the way from Earth's center to its surface. If the smaller mass is negligible compared to the larger the orbital parameters are independent of the smaller mass. For general orbits, the terms periapsis and apoapsis are used. Pericenter and apocenter are equivalent alternatives, referring explicitly to the respective points on the orbits, whereas periapsis and apoapsis may refer to the smallest and largest distances of the orbiter and its host.
For a body orbiting the Sun, the point of least distance is the perihelion, the point of greatest distance is the aphelion. The terms become apastron when discussing orbits around other stars. For any satellite of Earth, including the Moon, the point of least distance is the perigee and greatest distance the apogee, from Ancient Greek Γῆ, "land" or "earth". For objects in lunar orbit, the point of least distance is sometimes called the pericynthion and the greatest distance the apocynthion. Perilune and apolune are used. In orbital mechanics, the apsides technically refer to the distance measured between the barycenters of the central body and orbiting body. However, in the case of a spacecraft, the terms are used to refer to the orbital altitude of the spacecraft above the surface of the central body; these formulae characterize the pericenter and apocenter of an orbit: Pericenter Maximum speed, v per = μ a, at minimum distance, r per = a. Apocenter Minimum speed, v ap = μ a, at maximum distance, r ap = a.
While, in accordance with Kepler's laws of planetary motion and the conservation of energy, these two quantities are constant for a given orbit: Specific relative angular momentum h = μ a Specific orbital energy ε = − μ 2 a where: a is the semi-major axis: a = r per + r ap 2 μ is the standard gravitational parameter e is the eccentricity, defined as e = r ap − r per r ap + r per = 1 − 2 r ap r per + 1 Note t
Nicolas Camille Flammarion FRAS was a French astronomer and author. He was a prolific author of more than fifty titles, including popular science works about astronomy, several notable early science fiction novels, works on psychical research and related topics, he published the magazine L'Astronomie, starting in 1882. He maintained a private observatory at France. Camille Flammarion was born in Haute-Marne, France, he was the brother of founder of the Groupe Flammarion publishing house. He was a founder and the first president of the Société astronomique de France, which had its own independent journal, BSAF, first published in 1887. In January 1895, after 13 volumes of L'Astronomie and 8 of BSAF, the two merged, making L’Astronomie the Bulletin of the Societé; the 1895 volume of the combined journal was numbered 9, to preserve the BSAF volume numbering, but this had the consequence that volumes 9 to 13 of L'Astronomie can each refer to two different publications, five years apart from each other.
The "Flammarion engraving" first appeared in Flammarion's 1888 edition of L’Atmosphère. In 1907, he wrote that he believed that dwellers on Mars had tried to communicate with the Earth in the past, he believed in 1907 that a seven-tailed comet was heading toward Earth. In 1910, for the appearance of Halley's Comet, he believed the gas from the comet's tail "would impregnate atmosphere and snuff out all life on the planet."As a young man, Flammarion was exposed to two significant social movements in the western world: the thoughts and ideas of Darwin and Lamarck, the rising popularity of spiritism with spiritualist churches and organizations appearing all over Europe. He has been described as an "astronomer and storyteller", "obsessed by life after death, on other worlds, seemed to see no distinction between the two."He was influenced by Jean Reynaud and his Terre et ciel, which described a religious system based on the transmigration of souls believed to be reconcilable with both Christianity and pluralism.
He was convinced that souls after the physical death pass from planet to planet, progressively improving at each new incarnation. In 1862 he published his first book, The Plurality of Inhabited Worlds, was dismissed from his position at the Paris Observatory the same year, it is not quite clear. In Real and Imaginary Worlds and Lumen, he "describes a range of exotic species, including sentient plants which combine the processes of digestion and respiration; this belief in extraterrestrial life, Flammarion combined with a religious conviction derived, not from the Catholic faith upon which he had been raised, but from the writings of Jean Reynaud and their emphasis upon the transmigration of souls. Man he considered to be a “citizen of the sky,” others worlds “studios of human work, schools where the expanding soul progressively learns and develops, assimilating the knowledge to which its aspirations tend, approaching thus evermore the end of its destiny.”His psychical studies influenced some of his science fiction, where he would write about his beliefs in a cosmic version of metempsychosis.
In Lumen, a human character meets the soul of an alien, able to cross the universe faster than light, reincarnated on many different worlds, each with their own gallery of organisms and their evolutionary history. Other than that, his writing about other worlds adhered closely to current ideas in evolutionary theory and astronomy. Among other things, he believed that all planets went through more or less the same stages of development, but at different rates depending on their sizes; the fusion of science, science fiction and the spiritual influenced other readers as well. Flammarion's influence was great, not just on the popular thought of his day, but on writers with similar interests and convictions." In the English translation of Lumen, Brian Stapleford argues that both Olaf Stapledon and William Hope Hodgson have been influenced by Flammarion. Arthur Conan Doyle's The Poison Belt, published 1913 has a lot in common with Flammarion's worries that the tail of Halley's Comet would be poisonous for earth life.
Camille was a brother of Ernest Flammarion and Berthe Martin-Flammarion, uncle of a woman named Zelinda. His first wife was Sylvie Petiaux-Hugo Flammarion, his second wife was Gabrielle Renaudot Flammarion a noted astronomer. Beginning with Giovanni Schiaparelli's 1877 observations, 19th century astronomers observing Mars believed they saw a network of lines on its surface, which were named "canals" by Schiaparelli; these turned out to be an optical illusion due to the limited observing instruments of the time, as revealed by better telescopes in the 1920s. Camille, a contemporary of Schiaparelli, extensively researched the so-called "canals" during the 1880s and 1890s. Like American astronomer Percival Lowell, he thought the "canals" were artificial in nature and most the "rectification of old rivers aimed at the general distribution of water to the surface of the continents." He assumed the planet was in an advanced stage of its habitability, the canals were the product of an intelligent species attempting to survive on a dying world.
Flammarion approached spiritism, psychical research and reincarnation from the viewpoint of the scient
India known as the Republic of India, is a country in South Asia. It is the seventh largest country by area and with more than 1.3 billion people, it is the second most populous country as well as the most populous democracy in the world. Bounded by the Indian Ocean on the south, the Arabian Sea on the southwest, the Bay of Bengal on the southeast, it shares land borders with Pakistan to the west. In the Indian Ocean, India is in the vicinity of Sri Lanka and the Maldives, while its Andaman and Nicobar Islands share a maritime border with Thailand and Indonesia; the Indian subcontinent was home to the urban Indus Valley Civilisation of the 3rd millennium BCE. In the following millennium, the oldest scriptures associated with Hinduism began to be composed. Social stratification, based on caste, emerged in the first millennium BCE, Buddhism and Jainism arose. Early political consolidations took place under the Gupta empires. In the medieval era, Zoroastrianism and Islam arrived, Sikhism emerged, all adding to the region's diverse culture.
Much of the north fell to the Delhi Sultanate. The economy expanded in the 17th century in the Mughal Empire. In the mid-18th century, the subcontinent came under British East India Company rule, in the mid-19th under British Crown rule. A nationalist movement emerged in the late 19th century, which under Mahatma Gandhi, was noted for nonviolent resistance and led to India's independence in 1947. In 2017, the Indian economy was the world's sixth largest by nominal GDP and third largest by purchasing power parity. Following market-based economic reforms in 1991, India became one of the fastest-growing major economies and is considered a newly industrialised country. However, it continues to face the challenges of poverty, corruption and inadequate public healthcare. A nuclear weapons state and regional power, it has the second largest standing army in the world and ranks fifth in military expenditure among nations. India is a federal republic governed under a parliamentary system and consists of 29 states and 7 union territories.
A pluralistic and multi-ethnic society, it is home to a diversity of wildlife in a variety of protected habitats. The name India is derived from Indus, which originates from the Old Persian word Hindush, equivalent to the Sanskrit word Sindhu, the historical local appellation for the Indus River; the ancient Greeks referred to the Indians as Indoi, which translates as "The people of the Indus". The geographical term Bharat, recognised by the Constitution of India as an official name for the country, is used by many Indian languages in its variations, it is a modernisation of the historical name Bharatavarsha, which traditionally referred to the Indian subcontinent and gained increasing currency from the mid-19th century as a native name for India. Hindustan is a Middle Persian name for India, it was introduced into India by the Mughals and used since then. Its meaning varied, referring to a region that encompassed northern India and Pakistan or India in its entirety; the name may refer to either the northern part of India or the entire country.
The earliest known human remains in South Asia date to about 30,000 years ago. Nearly contemporaneous human rock art sites have been found in many parts of the Indian subcontinent, including at the Bhimbetka rock shelters in Madhya Pradesh. After 6500 BCE, evidence for domestication of food crops and animals, construction of permanent structures, storage of agricultural surplus, appeared in Mehrgarh and other sites in what is now Balochistan; these developed into the Indus Valley Civilisation, the first urban culture in South Asia, which flourished during 2500–1900 BCE in what is now Pakistan and western India. Centred around cities such as Mohenjo-daro, Harappa and Kalibangan, relying on varied forms of subsistence, the civilization engaged robustly in crafts production and wide-ranging trade. During the period 2000–500 BCE, many regions of the subcontinent transitioned from the Chalcolithic cultures to the Iron Age ones; the Vedas, the oldest scriptures associated with Hinduism, were composed during this period, historians have analysed these to posit a Vedic culture in the Punjab region and the upper Gangetic Plain.
Most historians consider this period to have encompassed several waves of Indo-Aryan migration into the subcontinent from the north-west. The caste system, which created a hierarchy of priests and free peasants, but which excluded indigenous peoples by labeling their occupations impure, arose during this period. On the Deccan Plateau, archaeological evidence from this period suggests the existence of a chiefdom stage of political organisation. In South India, a progression to sedentary life is indicated by the large number of megalithic monuments dating from this period, as well as by nearby traces of agriculture, irrigation tanks, craft traditions. In the late Vedic period, around the 6th century BCE, the small states and chiefdoms of the Ganges Plain and the north-western regions had consolidated into 16 major oligarchies and monarchies that were known as the mahajanapadas; the emerging urbanisation gave rise to non-Vedic religious movements, two of which became independent religions. Jainism came into prominence during the life of Mahavira.
Buddhism, based on the teachings of Gautama Buddha, attracted followers from all social classes excepting the middle
Rhea Silvia, known as Ilia, was the mythical mother of the twins Romulus and Remus, who founded the city of Rome. Her story is told in the first book of Ab Urbe Condita Libri of Livy and in fragments from Ennius and Quintus Fabius Pictor. According to Livy's account of the legend she was the daughter of Numitor, king of Alba Longa, descended from Aeneas. Numitor's younger brother Amulius seized the throne and killed Numitor's son forced Rhea Silvia to become a Vestal Virgin, a priestess of the goddess Vesta; as Vestal Virgins were sworn to celibacy for a period of thirty years, this would ensure the line of Numitor had no heirs. However, Rhea Silvia gave birth to the twins Romulus and Remus, she claimed. Livy says that she was raped by an unknown man, but "declared Mars to be the father of her illegitimate offspring, either because she imagined it to be the case, or because it was less discreditable to have committed such an offence with a god."When Amulius learned of the birth he imprisoned Rhea Silvia and ordered a servant to kill the twins.
But the servant showed mercy and set them adrift on the river Tiber, overflowing, left the infants in a pool by the bank. There, a she-wolf, who had just lost her own cubs, suckled them. Subsequently Faustulus rescued the boys; the god of the Tiber, rescued Rhea Silvia and took her to be his bride. Romulus would go on to found Rome, overthrow Amulius, reinstate Numitor as King of Alba Longa. Despite Livy's euhemerist and realist deflation of this myth, it is clear that the story of her seduction by Mars continued to be accepted; this is demonstrated by the recurring theme of Mars discovering Rhea Silvia in Roman arts: in bas-relief on the Casali Altar, in engraved couched glass on the Portland Vase, or on a sarcophagus in the Palazzo Mattei. Mars' discovery of Rhea Silvia is a prototype of the "invention scene", or "discovery scene" familiar in Roman art; the Portland Vase features a scene, interpreted as a depiction of the "invention", or coming-upon, of Rhea Sylvia by Mars. In a version presented by Ovid, it is the river Anio who takes pity on her and invites her to rule in his realm.
The name Rhea Silvia suggests a demi-goddess of forests. Silva means woods or forest, Rea may be related to res and regnum. Carsten Niebuhr proposed that the name Rhea Silvia came from Rea, meaning guilty, Silvia meaning of the forest and so assumed that Rhea Silvia was a generic name for the guilty woman of the forest, i.e. the woman, seduced there. Rhea Silvia appears as a minor goddess in Rick Riordan's fantasy novel The Mark of Athena, she and her husband Tiberinus assist demigod Annabeth Chase on her quest in Rome. She affects the appearance of Audrey Hepburn from the film Roman Holiday. In David Drake's Science Fiction story "To Bring the Light", the time travelling protagonist meets a human Rhea Silvia - a sympathetic peasant living in a small shepherd community on Palatine Hill in what would become the city of Rome. "Rhea Silva" is used as a password numerous times in the Doctor. Aeneas Founding of Rome Rhea Livy. Ab urbe condita, Book I. Quintus Ennius. "The Dream of Ilia", Annales - Book 1