Prominence

Structure that occurs above the photospherePoint where a star's atmosphere appears to become completely opaque. Thus, the photosphere may be thought of as the imaginary surface from which the starlight that we see appears to be emitted. The photosphere is not a thin surface; the Sun's photosphere has a thickness of ~100 km. (Within that Click on Term to Read More of the SunOur parent star. The structure of Sun's interior is the result of the hydrostatic equilibrium between gravity and the pressure of the gas. The interior consists of three shells: the core, radiative region, and convective region. Image source: http://eclipse99.nasa.gov/pages/SunActiv.html. The core is the hot, dense central region in which the. Prominences may reach high into the coronaExtended outer atmosphere of the Sun. The glow of the corona is a million times less bright than that of the photosphere; it can only be seen when the disk of the Sun is blocked during a total solar eclipse, or by using a coronagraph, which artificially blocks the disk Click on Term to Read More, often as graceful loops that may hang suspended for many days. Prominences are usually associated with regions of sunspotRegions on the Sun’s surface that appear dark because they are cooler than the surrounding photosphere, typically by ~1500-1800 K. Sunspots develop and persist for periods ranging from hours to months, and are carried around the surface of the Sun by its rotation. Sunspots travel in pairs (north and south activity and tend to lie on the boundary of regions having opposite magnetic polarity. Streaming arches and their stability for days at a time are associated with magnetic forces acting on the charged particles in the loops. The violently eruptive prominences that are sometimes observed are associated with corresponding sudden changes in the magnetic field of the Sun.