sentineles

The Sentinelese, also known as the Sentineli and the North Sentinel Islanders, are an indigenous people who inhabit North Sentinel Island in the Bay of Bengal in the northeastern Indian Ocean. Designated a Particularly Vulnerable Tribal Group and a Scheduled Tribe, they belong to the broader class of Andamanese peoples.

Along with the Great Andamanese, the Jarawas, the Onge, the Shompen, and the Nicobarese, the Sentinelese are one of the six native and often reclusive peoples of the Andaman and Nicobar Islands. Unlike the others, the Sentinelese appear to have consistently refused any interaction with the outside world. They are hostile to outsiders and have killed people who approached or landed on the island.[1]

In 1956, the Government of India declared North Sentinel Island a tribal reserve and prohibited travel within 3 nautical miles (5.6 kilometres) of it. It further maintains a constant armed patrol to prevent intrusions by outsiders. Photography is prohibited. There is significant uncertainty as to the group's size, with estimates ranging between 15 and 500 individuals, but mostly between 50 and 200.

A knight is a person granted an honorary title of knighthood by a head of state (including the pope) or representative for service to the monarch, the church or the country, especially in a military capacity.Knighthood finds origins in the Greek hippeis and hoplite (ἱππεῖς) and Roman eques and centurion of classical antiquity.

In the Early Middle Ages in Europe, knighthood was conferred upon mounted warriors. During the High Middle Ages, knighthood was considered a class of lower nobility. By the Late Middle Ages, the rank had become associated with the ideals of chivalry, a code of conduct for the perfect courtly Christian warrior. Often, a knight was a vassal who served as an elite fighter or a bodyguard for a lord, with payment in the form of land holdings. The lords trusted the knights, who were skilled in battle on horseback. Knighthood in the Middle Ages was closely linked with horsemanship (and especially the joust) from its origins in the 12th century until its final flowering as a fashion among the high nobility in the Duchy of Burgundy in the 15th century. This linkage is reflected in the etymology of chivalry, cavalier and related terms.

Luminosity is an absolute measure of radiated electromagnetic power (light), the radiant power emitted by a light-emitting object over time. In astronomy, luminosity is the total amount of electromagnetic energy emitted per unit of time by a star, galaxy, or other astronomical object.

In SI units, luminosity is measured in joules per second, or watts. In astronomy, values for luminosity are often given in the terms of the luminosity of the Sun, L⊙. Luminosity can also be given in terms of the astronomical magnitude system: the absolute bolometric magnitude (Mbol) of an object is a logarithmic measure of its total energy emission rate, while absolute magnitude is a logarithmic measure of the luminosity within some specific wavelength range or filter band.

In contrast, the term brightness in astronomy is generally used to refer to an object's apparent brightness: that is, how bright an object appears to an observer. Apparent brightness depends on both the luminosity of the object and the distance between the object and observer, and also on any absorption of light along the path from object to observer. Apparent magnitude is a logarithmic measure of apparent brightness. The distance determined by luminosity measures can be somewhat ambiguous, and is thus sometimes called the luminosity distance.