Science (from Latin scientia, meaning "knowledge") is a systematic enterprise that builds and organizes knowledge in the form of testable explanations and predictions about the universe.
From classical antiquity through the 19th century, science as a type of knowledge was more closely linked to philosophy. In the West, the term natural philosophy encompassed fields of study that are currently associated with disciplines such as classical physics, astronomy and medicine and was a precursor of modern natural sciences (life science and physical science). In the 17th and 18th centuries, scientists increasingly sought to formulate knowledge in terms of laws of nature. Over the centuries, the term science became associated with the scientific method, a systematic way of studying the natural world and particularly in the 19th century, multiple distinguishing characteristics of contemporary modern science began to take shape.
Modern science is typically divided into three major branches that consist of the natural sciences (e.g. biology, chemistry, physics), which study nature in the broadest sense; the social sciences (e.g. psychology, sociology, economics), which study individuals and societies; and the formal sciences (e.g. mathematics, logic, theoretical computer science), which study abstract concepts. There is disagreement, however, on the formal sciences being a science as they do not rely on empirical evidence. Disciplines that use science, such as engineering and medicine, are described as applied sciences.
Science is related to research and is commonly organized by academic and research institutions as well as government agencies and companies. The practical impact of scientific research has led to the emergence of science policies that seek to influence the scientific enterprise by prioritizing the development of commercial products, armaments, health care, and environmental protection.
is a small body in the solar system that orbits the Sun
and (at least occasionally) exhibits a coma
(or atmosphere) and/or a tail — both due primarily to the effects of solar radiation upon the comet's nucleus
, which itself is a minor planet composed of rock, dust, and ices. Due to their origins in the outer solar system and their propensity to be highly affected (or perturbed
) by relatively close approaches to the major planets, comets' orbits are constantly changing. Some are moved into sungrazing orbits that destroy the comets when they are too near the Sun, while others are thrown out of the solar system forever.
Most comets are believed to originate in a cloud (the Oort cloud) at large distances from the Sun consisting of debris left over from the condensation of the solar nebula; the outer edges of such nebulae are cool enough that water exists in a solid (rather than gaseous) state. Asteroids originate via a different process, but very old comets which have lost all their volatile materials may come to resemble asteroids.
A Tesla coil is a category of disruptive discharge transformer coils, named after their inventor, Nikola Tesla. Tesla coils are composed of coupled resonant electric circuits. Nikola Tesla actually experimented with a large variety of coils and configurations, so it is difficult to describe a specific mode of construction that will meet the wants of those who ask about "Tesla" coils. "Early coils" and "later coils" vary in configuration and setup. Tesla coils in general are very popular devices among high-voltage enthusiasts.