Solar phenomena
| Heliophysics | |
| Phenomena | |
|---|---|
Solar phenomena are the natural phenomena occurring within the magnetically heated outer atmospheres in the Sun. These phenomena take many forms, including solar wind, radio wave flux, energy bursts such as solar flares, coronal mass ejection or solar eruptions, coronal heating and sunspots.
These phenomena are generated by a helical dynamo near the center of the Sun's mass that generates strong magnetic fields and a chaotic dynamo near the surface that generates smaller magnetic field fluctuations.
The total sum of all solar fluctuations is referred to as solar variation. The collective effect of all solar variations within the Sun's gravitational field is referred to as space weather. A major weather component is the solar wind, a stream of plasma released from the Sun's upper atmosphere. It is responsible for the aurora, natural light displays in the sky in the Arctic and Antarctic. Space weather disturbances can cause solar storms on Earth, disrupting communications, as well as geomagnetic storms in Earth's magnetosphere and sudden ionospheric disturbances in the ionosphere. Variations in solar intensity also affect Earth's climate. These variations can explain events such as ice ages and the Great Oxygenation Event, while the Sun's future expansion into a red giant will likely end life on Earth.
Solar activity and related events have been recorded since the 8th century BCE. Babylonians inscribed and possibly predicted solar eclipses, while the earliest extant report of sunspots dates back to the Chinese Book of Changes, c. 800 BCE. The first extant description of the solar corona was in 968, while the earliest sunspot drawing was in 1128 and a solar prominence was described in 1185 in the Russian Chronicle of Novgorod. The invention of the telescope allowed major advances in understanding, allowing the first detailed observations in the 1600s. Solar spectroscopy began in the 1800s, from which properties of the solar atmosphere could be determined, while the creation of daguerreotypy led to the first solar photographs on 2 April 1845. Photography assisted in the study of solar prominences, granulation and spectroscopy. Early in the 20th century, interest in astrophysics surged in America. A number of new observatories were built with solar telescopes around the world. The 1931 invention of the coronagraph allowed the corona to be studied in full daylight.
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Wikipedia