northanger (northanger) wrote,
northanger
northanger

solar stuff [current sunspot #736]

@spaceweather.com

SOLAR FILAMENT: Today (20-Feb) on the sun there's an enormous dark filament stretching 300,000+ miles from end to end--greater than the distance between Earth and the Moon. Experienced solar observers say it's one of the longest they've ever seen. Filaments are magnetic tubes suspended above the surface of the sun and filled with dense gas. Because the gas is cooler than the sun below it, filaments appear dark. Sometimes filaments erupt, producing a "Hyder flare." More often they don't. This one will probably persist for many days to come.

SOLAR EXPLOSION: Yesterday (20-Feb) something exploded on the sun. We couldn't see the blast from Earth because the blast-site was hidden behind the sun's western limb. But the massive cloud it hurled into space was spotted by photographer Gary Palmer: "Wow!" says Palmer. "This ultra-fast moving cloud re-wrote the definition of 'speed.'" It was pretty, too. Solar farside explosions like this one have no effect on Earth, but they can interact with other planets. Yesterday's blast was directed more or less toward Mars.


SIDC A filament is a cloud of plasma suspended above the solar surface. Magnetic arcades act as a hammock in which the plasma rests. The filament appears as a dark ribbon in pictures like H-alpha (visible light) since it absorbs radiation coming from the plasma below and emits (scatters) it in all directions, so that there is a net decrease in the amount of radiation coming towards us. If the magnetic field structure around the cooler plasma breaks open, the plasma can be thrown into space: this is a filament eruption and may lead to a CME. The series of pictures above tells us where the filament is (SOHO/EIT304, orange) and where the footpoints of the magnetic arcades creating the plasma tube, are located (SOHO/MDI, black/white/grey). The filament is situated between a positive (white) and a negative (black) magnetic field area which are connected by the magnetic arcades.

Joint USAF/NOAA Report of Solar and Geophysical Activity SDF Number 051 Issued at 2200Z on 20 Feb 2005 - IA. Analysis of Solar Active Regions and Activity from 19/2100Z to 20/2100Z: Solar activity decreased to very low levels. A long duration B-class flare was observed at 20/1628Z from just beyond the solar west limb. This event is believed to be from Region 732 (N08 L=188) which rotated out of view on 18 February. Region 735 (S09W58) has changed little since yesterday and remains a magnetic beta-gamma group. Region 736 (N13W50) is a weak beta magnetic region that was numbered today.

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