Topic: Weather/Space weather
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π Saturn's Hexagon
Saturn's hexagon is a persistent approximately hexagonal cloud pattern around the north pole of the planet Saturn, located at about 78Β°N. The sides of the hexagon are about 14,500Β km (9,000Β mi) long, which is about 2,000Β km (1,200Β mi) longer than the diameter of Earth. The hexagon may be a bit more than 29,000Β km (18,000Β mi) wide, may be 300Β km (190Β mi) high, and may be a jet stream made of atmospheric gases moving at 320Β km/h (200Β mph). It rotates with a period of 10h 39m 24s, the same period as Saturn's radio emissions from its interior. The hexagon does not shift in longitude like other clouds in the visible atmosphere.
Saturn's hexagon was discovered during the Voyager mission in 1981, and was later revisited by Cassini-Huygens in 2006. During the Cassini mission, the hexagon changed from a mostly blue color to more of a golden color. Saturn's south pole does not have a hexagon, as verified by Hubble observations. It does, however, have a vortex, and there is also a vortex inside the northern hexagon. Multiple hypotheses for the hexagonal cloud pattern have been developed.
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- "Saturn's Hexagon" | 2024-02-29 | 71 Upvotes 7 Comments
π Carrington Event
The Carrington Event was the most intense geomagnetic storm in recorded history, peaking from 1β2 September 1859 during solar cycle 10. It created strong auroral displays that were reported globally and caused sparking and even fires in multiple telegraph stations. The geomagnetic storm was most likely the result of a coronal mass ejection (CME) from the Sun colliding with Earth's magnetosphere.
The geomagnetic storm was associated with a very bright solar flare on 1 September 1859. It was observed and recorded independently by British astronomers Richard Christopher Carrington and Richard Hodgsonβthe first records of a solar flare.
A geomagnetic storm of this magnitude occurring today would cause widespread electrical disruptions, blackouts, and damage due to extended outages of the electrical power grid.
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- "Carrington Event" | 2024-05-12 | 43 Upvotes 16 Comments
π Miyake event β estimated to be every 400β2400 years
A Miyake event is an observed sharp enhancement of the production of cosmogenic isotopes by cosmic rays. It can be marked by a spike in the concentration of radioactive carbon isotope 14
C in tree rings, as well as 10
Be and 36
Cl in ice cores, which are all independently dated. At present, five significant events are known (7176 BCE, 5259 BCE, 660 BCE, 774 CE, 993 CE) for which the spike in 14
C is quite remarkable, i.e. above 1% rise over a period of 2 years, and four more events (12,350Β BCE, 5410 BCE, 1052 CE, 1279 CE) need independent confirmation. It is not known how often Miyake events occur, but from the available data it is estimated to be every 400β2400 years.
There is strong evidence that Miyake events are caused by extreme solar particle events and they are likely related to super-flares discovered on solar-like stars. Although Miyake events are based on extreme year-to-year rises of 14
C concentration, the duration of the periods over which the 14
C levels increase or stay at high levels is longer than one year. However, a universal cause and origin of all the events is not yet established in science, and some of the events may be caused by other phenomena coming from outer space (such as a gamma-ray burst).
A recently reported sharp spike in 14
C that occurred between 12,350 and 12,349Β BCE, may represent the largest known Miyake event. This event was identified during a study conducted by an international team of researchers who measured radiocarbon levels in ancient trees recovered from the eroded banks of the Drouzet River, near Gap, France, in the Southern French Alps. According to the initial study the new event is roughly twice the size of the Ξ14
C increase for more recent 774Β CE and 993Β CE events, but the strength of the corresponding solar storm is not yet assessed. However, the newly discovered 12,350 BCE event has not yet been independently confirmed in wood from other regions, nor it is reliably supported by a clear corresponding spike in other isotopes (such as Beryllium-10) that are usually used in combination for absolute radiometric dating.
A Miyake event occurring in modern conditions might have significant impacts on global technological infrastructure such as satellites, telecommunications, and power grids.