A prominence is a large, bright, gaseous feature extending outward from the Sun’s surface, often in a loop shape. Prominences are anchored to the Sun’s surface in the photosphere, and extend outwards into the Sun’s corona. While the corona consists of extremely hot ionized gases, known as plasma, which do not emit much visible light, prominences contain much cooler plasma, similar in composition to that of the chromosphere. The prominence plasma is typically a hundred times cooler and denser than the coronal plasma. A prominence forms over timescales of about a day, and prominences may persist in the corona for several weeks or months. Some prominences break apart and may then give rise to coronal mass ejections. Scientists are currently researching how and why prominences are formed.
A typical prominence extends over many thousands of kilometers; the largest on record was estimated at over 800,000 kilometres (500,000 mi) long – roughly the radius of the Sun.
When a prominence is viewed from a different perspective so that it is against the sun instead of against space, it appears darker than the surrounding background. This formation is instead called a solar filament. It is possible for a projection to be both a filament and a prominence. Some prominences are so powerful that they throw out matter from the Sun into space at speeds ranging from 600 km/s to more than 1000 km/s. Other prominences form huge loops or arching columns of glowing gases over sunspots that can reach heights of hundreds of thousands of kilometers. Prominences may last for a few days or even for a few months.
Imaging telescopes or lenses: Istar Optical refractor 230 mm F/D 9 Anastigmatic Special H-Alpha R30
Imaging cameras: Basler ACA1300
Mounts: Astro-Physics AP 1200 GTO
Image Credit & Copyright: Alan Friedman (Averted Imagination)
Our Sun has become quite a busy place. Taken only two weeks ago, the Sun was captured sporting numerous tumultuous regions including active sunspot regions AR 2036 near the image top and AR 2036near the center. Only four years ago the Sun was emerging from an unusually quiet Solar Minimum that had lasted for years. The above image was recorded in a single color of light called Hydrogen Alpha, inverted, and false colored. Spicules cover much of the Sun’s face like a carpet. The gradual brightening towards the Sun’s edges is caused by increased absorption of relatively cool solar gas and called limb darkening. Just over the Sun’s edges, several filamentary prominences protrude, while prominences on the Sun’s face are seen as light streaks. Possibly the most visually interesting of all are the magnetically tangled active regions containing relatively cool sunspots, seen as white dots. Currently at Solar Maximum — the most active phase in its 11-year magnetic cycle, the Sun’s twisted magnetic field is creating numerous solar “sparks” which include eruptive solar prominences, coronal mass ejections, and flares which emit clouds of particles that may impact the Earth and cause auroras. One flare two years ago released such a torrent of charged particles into the Solar System that it might have disrupted satellites and compromised power grids had it struck planet Earth.
NASA APOD 06-May-14
Image Credit & Copyright: jp-BrahicExplanation:
Dramatic prominences can sometimes be seen looming just beyond the edge of the sun. Such was the case last week as a large prominence, visible above, highlighted a highly active recent Sun. A waving sea of hot gas is visible in the foreground chromosphere in great detail as it was imaged in one specific color of light emitted by hydrogen. A solar prominence is a cloud of solar gas held just above the surface by the Sun’s magnetic field. The Earth, illustrated in the inset, is smaller than the prominence. Although very hot, prominences typically appear dark when viewed against the Sun, since they are slightly cooler than the photosphere below them. A quiescent prominence typically lasts about a month, and may erupt in a Coronal Mass Ejection (CME) expelling hot gas into the Solar System, some of which may strike the Earth and trigger auroras.
NASA APOD 04-Mar-2014
A solar prominence (also known as a filament) is an arc of gas that erupts from the surface of the Sun. Prominences can loop hundreds of thousands of miles into space. Prominences are held above the Sun’s surface by strong magnetic fields and can last for many months. At some time in their existence, most prominences will erupt, spewing enormous amounts of solar material into space.
Equipment: Coronado 90 + SBIG 8300s + LX75
Time GMT: 23:30:00
Exposure 0.1 sec.