Corona is a term that refers to a variety of phenomena characterized by a "crown-like" appearance. In science, it is commonly used to describe the outer atmosphere of the sun, the glow around high voltage electrical conductors, and a type of virus.
The sun's corona is the outermost layer of the sun's atmosphere, visible during a total solar eclipse as a pearly white halo surrounding the dark disk of the moon. It is much hotter than the sun's surface and is the source of the solar wind.
Electrical corona occurs when the electric field near a conductor is strong enough to ionize the surrounding air, creating a faint glow. This phenomenon is often seen as a bluish glow around high voltage power lines or electrical equipment during stormy weather.
Coronaviruses are a group of related RNA viruses that cause diseases in mammals and birds. In humans, they are known to cause respiratory infections ranging from the common cold to more severe diseases such as Middle East Respiratory Syndrome (MERS) and Severe Acute Respiratory Syndrome (SARS). The most recent coronavirus, SARS-CoV-2, is responsible for the COVID-19 pandemic.